Namecoin TLS for Firefox: Phase 1 (Overrides in C++)

Making TLS work for Namecoin websites in Firefox has been an interesting challenge. On the positive side, Mozilla has historically exposed a number of API’s that would be useful for this purpose, and we’ve actually produced a couple of Firefox extensions that used them: the well-known Convergence for Namecoin codebase (based on Convergence by Moxie Marlinspike and customized for Namecoin by me), and the much-lesser-known nczilla (written by Hugo Landau and me, with some code borrowed from Selenium). This was a pretty big advantage over Chromium, whose developers have consistently refused to support our use cases (which forced us to use the dehydrated certificate witchcraft). On the negative side, Mozilla has a habit of removing useful API’s approximately as fast as we notice new ones. (Convergence’s required API’s were removed by Mozilla about a year or two after we started using Convergence, and nczilla’s required API’s were removed before nczilla even had a proper release, which is why nearly no one has heard of nczilla.) On the positive side, Mozilla has expressed an apparent willingness to entertain the idea of merging officially supported API’s for our use case. So, I’ve been hacking around with a fork of Firefox, hoping to come up with something that Mozilla could merge in the future. Phase 1 of that effort is now complete.

In particular, I’ve created a C++ XPCOM component (compiled into my fork of Firefox) that hooks the certificate verification functions, and can produce both positive and negative overrides (meaning, respectively, that it can make invalid certs appear valid, and make valid certs appear invalid). This XPCOM component has access to most of the data that we would want: it has access to the certificate, the hostname, and quite a lot of other data that Firefox stores in objects that the XPCOM component has access to. Unfortunately, it doesn’t yet have access to the full certificate chain (I’m still investigating how to do that), and it also doesn’t yet have access to the proxy settings (I do see how to do that, it’s just not coded yet). The full certificate chain would be useful if you want to run your own CA; the proxy settings would be useful for Tor stream isolation with headers-only Namecoin SPV clients.

Performance is likely to be impacted, since this code is not even close to optimized (nor is performance even measured). I’ll be investigating performance later. Short-term, my next step will be to delegate the override decisions to JavaScript code. (This looks straightforward, but as we all know, our friend Murphy might strike at any time.) After that I’ll be looking at making that JavaScript code delegate decisions to WebExtensions. The intention here is to support use cases besides Namecoin’s. The WebExtensions API that this would expose would presumably be useful for DNSSEC/DANE verification, perspective verification, and maybe other interesting experiments that I haven’t thought of.

Major thanks to David Keeler from Mozilla for answering some questions in IRC that I had about how the Firefox certificate verification code is structured.

Hopefully I’ll have more news on this subject in the next couple weeks.

This work was funded by NLnet Foundation’s Internet Hardening Fund.

Refactoring the Raw Transaction API

Several improvements are desirable for how Namecoin Core creates name transactions:

  • Register names without having to unlock the wallet twice, 12 blocks apart.
  • Coin Control (a method of improving anonymity).
  • Specifying a fee based on when you need the transaction to be confirmed.
  • Pure name transactions (a method of improving scalability of Namecoin by decreasing transaction size).

All of these improvements, though they seem quite different in nature, have one important thing in common: they need to use the raw transaction API in ways that Namecoin Core doesn’t make easy.

What’s the raw transaction API?

Simply put, the raw transaction API is a Bitcoin Core feature that allows the user to create custom transactions at a much lower level than what a typical user would want. The raw transaction API gives you a lot of power and flexibility, but it’s also more cumbersome and, if used incorrectly, you can accidentally lose lots of money.

Why do those features need the raw transaction API?

The raw transaction API is useful for a few reasons. First, it lets you create and sign transactions independently from broadcasting them. That means you can create and sign a name_firstupdate transaction before its preceding name_new transaction has been broadcast. Second, it gives you direct control over the inputs, outputs, and fees for the transaction, whereas the standard name commands instead pick defaults for you that you might not like and can’t change.

What’s wrong with Namecoin Core’s raw transaction API?

It’s not raw enough! First off, the only name transactions it can create are name_update; it can’t create name_new or name_firstupdate transactions. That rules out handling name registrations, and consequently means that anonymously registering names or controlling the fee for name registrations is a no-go. Secondly, it can’t create name_update outputs with a higher monetary value than the default 0.01 NMC. That rules out pure name transactions.

How are we fixing this?

We’re making an API change. Instead of trying to stuff name operation data into createrawtransaction, where it doesn’t belong and where it’s extremely difficult to provide the needed flexibility, we’re removing name support from createrawtransaction and moving it to a new RPC call, namerawtransaction. The new workflow replaces the previous createrawtransaction with two steps:

  1. Use createrawtransaction just like you would with Bitcoin, and specify a currency output of 0.01 NMC for where you want the name output to be.
  2. Use namerawtransaction to prepend a name operation to the scriptPubKey of the aforementioned currency output. This has the effect of converting that currency output into a name output.

What will be the impact?

Users of the raw transaction API will need to update their code. If you’re using the raw transaction API to create currency transactions, then this will actually allow you to delete your Namecoin-specific customizations, since it will be just like Bitcoin again. If you’re using the raw transaction API to create name transactions (this includes people who are doing atomic name trading), you’ll need to refactor your createrawtransaction-using code so that it also calls namerawtransaction. If you’re a hacker who enjoys experimenting, this new workflow will probably be much more to your liking, as it will allow you to do stuff that you couldn’t easily do before. And if you’re just an average user of Namecoin-Qt, you’ll probably like the new features that this enables, such as easier registration of names, better privacy, and lower fees.

Who’s involved in this work?

  • Jeremy Rand wrote a rough spec for the new API.
  • Daniel Kraft is implementing the changes to the API.
  • Jeremy Rand plans to utilize the new API in proof-of-concept scripts for several use cases (including the above 4 use cases).
  • Brandon Roberts plans to convert Jeremy’s proof-of-concept scripts into GUI features in Namecoin-Qt.

This work was funded in part by NLnet Foundation’s Internet Hardening Fund.

What might come later?

Maybe Namecoin-Qt support for atomic name trading? :)

BitcoinJ support merged into ncdns-nsis

The ncdns-nsis project, which provides a zero-configuration Windows installer for Namecoin domain name resolution functionality, has merged SPV support, implemented via BitcoinJ. This enables Windows machines to resolve .bit domain names without having to download the full Namecoin chain.

Merging this functionality means that Namecoin domain names can be resolved on Windows client machines with only a minimal chain synchronization and storage burden, in exchange for a limited reduction in the security level provided.

Installer binaries will be published in due course as remaining ncdns-nsis issues are concluded.

To use the BitcoinJ client, run the ncdns-nsis installer and select the SPV option when asked whether to install a Namecoin node. Run BitcoinJ after installation and wait for synchronization to complete; .bit name resolution is then available.

Video, Slides, and Paper from Namecoin at GCER 2017

As was announced, I represented Namecoin at the 2017 Global Conference on Educational Robotics. Although GCER doesn’t produce official recordings of their talks, I was able to obtain an amateur recording of my talk from an audience member. I’ve also posted my slides, as well as my paper from the conference proceedings.

It should be noted that, as this is an amateur recording, the audio quality is not spectacular. It should also be noted that the audience is rather different from the audiences for whom I usually give Namecoin talks; as a result, the focus of the content is also rather different from my usual Namecoin talks.

The WebM amateur video recording of my talk is here (hosted by

My slides are available here.

My paper is available here.

Huge thanks to the staff and volunteers from KISS Institute for Practical Robotics, who organized GCER. Especially big thanks to Roger Clement and Steve Goodgame for giving me excellent feedback on the general outline of my paper and talk. This was an excellent event, and I look forward to the next time I’m able to attend.

ncdns v0.0.4 Released

We’ve released ncdns v0.0.4. This release incorporates a bugfix in the madns dependency, which fixes a DNSSEC signing bug. The ncdns Windows installer in this release also updated the Dnssec-Trigger dependency.

As usual, you can download it at the Beta Downloads page.

This work was funded by NLnet Foundation’s Internet Hardening Fund.

TLS Support for Chromium on Windows Released

After quite a bit of code cleanup, we’ve released a new beta of ncdns for Windows, which includes Namecoin-based TLS certificate validation for Chromium, Google Chrome, and Opera on Windows. This includes both the CryptoAPI certificate injection and NUMS HPKP injection that were discussed previously. You can download it on the Beta Downloads page. We’ve also posted binaries of ncdns (without install scripts or TLS support) for a number of other operating systems; they’re also linked on the Beta Downloads page.

Credit for this release goes to:

  • Jeremy Rand: Cert injection Go implementation; NUMS HPKP injection concept and Go implementation; review of Hugo’s code.
  • Hugo Landau: Cert injection NSIS implementation; NUMS HPKP injection NSIS implementation; review of Jeremy’s code.
  • Ryan Castellucci: Dehydrated certificates concept+algorithm; NUMS hash algorithm and Python implementation.

This work was funded by NLnet Foundation’s Internet Hardening Fund.

Meanwhile, Namecoin TLS development focus has started to shift toward Firefox TLS support.

QCon London 2017 Video: Case Study: Alternate Blockchains

LibreTorNS Merged to Upstream TorNS

Generally I’m of the opinion that it’s better to get patches to other people’s projects merged upstream whenever feasible; accordingly I submitted the LibreTorNS patches upstream. Happily, meejah has merged the LibreTorNS patches to upstream TorNS. That means LibreTorNS is now obsolete, and you should use meejah’s upstream TorNS for testing dns-prop279 going forward.

Huge thanks to meejah for accepting the patch! Also thanks to meejah for the code review – there was a bug hiding in my initial submitted patch, which is one of the reasons I always prefer getting things reviewed by upstream.

Namecoin’s Jeremy Rand will be a speaker at GCER 2017

I will be speaking at the 2017 Global Conference on Educational Robotics (July 8-12, 2017). For those of you unfamiliar with GCER, the audience is mostly a mix of middle school students, high school students, college students, and educators, most of whom are participating in the robotics competitions hosted at GCER (primarily Botball). I competed in Botball (and the other 2 GCER competitions: KIPR Open and KIPR Aerial) between 2003 and 2015, and that experience (particularly the hacking aspect, which is actively encouraged in all three competitions) was a major factor in why I’m a Namecoin developer. My talk is an outreach effort, which I hope will result in increased interest in the Botball scene in the areas of privacy, security, and human rights. My talk (scheduled for July 10) is entitled “Making HTTPS and Anonymity Networks Slightly More Secure (Or: How I’m Using My Botball Skill Set in the Privacy/Security Field)”.

Huge thanks to KISS Institute for Practical Robotics (which organizes GCER) for suggesting that I give this talk. Looking forward to it!

QCon London 2017 Video: Practical Cryptography & Blockchain Panel

Namecoin Resolution for Tor Released

The aforementioned licensing issues with TorNS have been dealt with, and I’ve released the DNS provider for Tor’s Prop279 Pluggable Naming API. This allows Namecoin resolution in Tor.

One issue I encountered is that TorNS currently implements a rather unfortunate restriction that input and output domain names must be in the .onion TLD. I’ve created a fork of TorNS (which I call LibreTorNS) which removes this restriction. LibreTorNS is currently required for Namecoin usage.

The code is available from the Beta Downloads page. Please let me know what works and what doesn’t. And remember, using Namecoin naming with Tor will make you heavily stand out, so don’t use this in any scenario where you need anonymity. (Also please refer to the extensive additional scary warnings in the readme if you’re under the mistaken impression that using this in production is a good idea.)

This development was funded by NLnet.

Namecoin Resolution for Tor (DNS Provider for Tor Prop279 Pluggable Naming API)

A while back, I released on the tor-dev mailing list a tool for using Namecoin naming with Tor. It worked, but it was clearly a proof of concept. For example, it didn’t implement most of the Namecoin domain names spec, it didn’t work with the libdohj client, and it used the Tor controller API. I’ve now coded a new tool that fixes these issues.

Fixing the spec compliance and libdohj compatibility was implemented by using ncdns as a backend instead of directly talking to Namecoin Core. Interestingly, I decided not to do anything Namecoin-specific with this tool. It simply uses the DNS protocol to talk to ncdns, or any other DNS server you provide. (So yes, that means that you could, in theory, use the DNS instead of Namecoin, without modifying this tool at all.)

In order to work with the DNS protocol, some changes were made to how .onion domains are stored in Namecoin. The existing convention is to use the tor field of a domain, which has no DNS mapping. Instead, I’m using the txt field of the _tor subdomain of a domain. This is consistent with existing practice in the DNS world.

This tool is using Tor’s Prop279 Pluggable Naming protocol rather than the Tor controller API. Right now tor (little-t) doesn’t implement Prop279. To experiment with Prop279, TorNS is a useful way of simulating Prop279 support using the control port as a backend. Unfortunately, TorNS’s license is unclear at the moment. I’m in the process of checking with meejah (author of TorNS) to see if TorNS can be released under a free software license. Until that minor bit of legalese is taken care of, the release of Namecoin resolution for Tor is on hold.

This development was funded by NLnet.

Automated Nothing-Up-My-Sleeve HPKP Insertion for Chromium

As I mentioned in my previous post, we protect from compromised CA’s by using a nothing-up-my-sleeve (NUMS) HPKP pin in Chromium. Previously, it was necessary for the user to add this pin themselves in the Chromium UI. This was really sketchy from both a security and UX point of view. I have now submitted a PR to ncdns that will automatically add the necessary pin.

This is implemented as a standalone program that is intended to be run at install. It works by parsing Chromium’s TransportSecurity storage file (which is just JSON), adding an entry for bit that contains the NUMS key pin, and then saving the result as JSON back to TransportSecurity.

I expect this to work for most browsers based on Chromium (e.g. Chrome and Opera), on most OS’s (e.g. GNU/Linux, Windows, and macOS), but so far I’ve only tested with Chrome on Windows. I don’t expect it to work with Electron-based applications such as Riot and Brave; Electron doesn’t seem to follow the standard Chromium conventions on HPKP. I haven’t yet examined Electron to see if there’s a way we can get it to work.

This isn’t yet integrated with the NSIS installer; I’ll be asking Hugo to take a look at doing the integration there.

Progress on Electrum-NMC

Work on the electrum port for Namecoin has been moving along nicely. It was decided that we will use the electrum-client from spesmilo, along with the electrumX server. ElectrumX was chosen due to the original electrum-server being discontinued a few months ago. So far the electrum client has been ported over for compatability with electrumX. This includes the re-branding, blockchain parameters and other electrum related settings for blockchain verification

On the roadmap now are:

  • Extend electrumX NMC Support to allow for full veritification of AuxPow
  • Modify new electrum client to verify the new AuxPow
  • Add Name handling support to electrum

These repo’s are for testing purposes only. Do not use these unless your willing to risk losing funds.

Server/ Not uploaded yet

How we’re doing TLS for Chromium

Back in the “bad old days” of Namecoin TLS (circa 2013), we used the Convergence codebase by Moxie Marlinspike to integrate with TLS implementations. However, we weren’t happy with that approach, and have abandoned it in favor of a new approach: dehydrated certificates.

What’s wrong with Convergence? Convergence uses a TLS intercepting proxy to replace the TLS implementation used by web browsers. Unfortunately, TLS is a really difficult and complex protocol to implement, and the nature of intercepting proxies means that if the proxy makes a mistake, the web browser won’t protect you. It’s fairly commonplace these days to read news about a widely deployed TLS intercepting proxy that broke things horribly. Lenovo’s SuperFish is a well-known example of a TLS intercepting proxy that made its users less safe.

Convergence was in a somewhat special situation, though: it reused a lot of code that was distributed with Firefox (via the js-ctypes API), which reduced the risk that it would do something horribly dangerous with TLS. It was also originally written by Moxie Marlinspike (well-known for Signal), which additionally reduced the risk of problems. Unfortunately, Mozilla stopped shipping the relevant code with Firefox, Moxie stopped maintaining Convergence, and Mozilla decided to deprecate additional functionality that was used by Convergence. This made it clear that the Convergence codebase wasn’t going to be viable, and that if we wanted to use an intercepting proxy, we’d be using a codebase that was substantially less reliable than Convergence.

So, we went back to the drawing board, and came up with a new solution.

As a first iteration, TLS implementations have a root CA trust store, and injecting a self-signed end-entity x509 certificate into the root CA trust store will allow that certificate to be trusted for use by a website. (For an explanation of how this can be done with Windows CryptoAPI, see my previous post, Reverse-Engineering CryptoAPI’s Certificate Registry Blobs). We can do this right before the TLS connection is opened by hooking the DNS request for the .bit domain (this is easy since we control the ncdns codebase that processes the DNS request).

However, there are three major issues with this approach:

  1. An x509 certificate is very large, and storing this in the blockchain would be too expensive. Using a fingerprint would be much smaller, but we can’t recover the full certificate from just the fingerprint.
  2. x509 certificates might be valid for a different purpose than advertised. For example, if we injected a certificate that has the CA bit enabled, the owner of that certificate would be able to impersonate arbitrary websites if they can get you to first visit their malicious .bit domain. x509 is a complex specification, and we don’t want to try to detect every possible type of mischief that can be done with them.
  3. Injecting a certficate doesn’t prevent a malicious CA that is trusted for DNS names from issuing fraudulent certificates for .bit domain names.

Problems 1 and 2 can be solved at the same time. First, we use ECDSA certificates instead of the typical RSA. ECDSA is supported by all recent TLS implementations, but RSA is largely dominant because of inertia and the prevalence of outdated software. By excluding the old software that relies on RSA, we get much smaller keys and signatures. (Old software isn’t usable with this scheme anyway, because of our solution to Problem 3.)

Next, instead of having domain owners put the entire ECDSA x509 certificate in the blockchain, the domain owner extracts only 4 components of the certificate: the public key, the start and end timestamps for the valdity period, and the signature. As long as the rest of the certificate conforms to a fixed template, those 4 components (which we call a dehydrated certificate) can be combined with a domain name and the template, and rehydrated into a fully valid x509 certificate that can be injected into the trust store. This technique was invented by Namecoin’s Lead Security Engineer, Ryan Castellucci.

It should be noted that a dehydrated certificate can’t do any mischief such as being valid for unexpected uses; all of the potentially dangerous fields are provided by the template, which is part of ncdns. The dehydrated data is also quite small: circa 252 bytes (we can probably shrink it further in the future). Implementing this in ncdns was a little bit tricky, because the Go standard library’s x509 functions that are needed to perform the signature splicing are private. I ended up forking the Go x509 package, and adding a public function that exposes the needed functionality. (Before you freak out about me forking the x509 package, my package consists of a single file that contains the additional function, and a Bash script that copies the official x509 library into my fork. It’s reasonably self-contained and shouldn’t run into the issues that more invasive forks encounter regularly.)

So what about Problem 3? Well, for this, I ~~abuse~~ take advantage of an interesting quirk in browser implementations of HPKP (HTTPS Public Key Pinning). Browsers only enforce key pins against certificates for built-in certificate authorities; user-specified certificate authorities are exempt from HPKP. This behavior is presumably to make it easier for users to intentionally intercept their own traffic (or for corporations to intercept traffic in their network, which is a less ethical version of a technologically identical concept). As such, I believe that this behavior will not go away anytime soon, and is safe to rely on. The user places a key pin at the bit domain, with subdomains enabled, for a “nothing up my sleeve” public key hash. As a result, no public CA can sign certificates for any domain ending in .bit, but user-specified CA’s can. Windows CryptoAPI treats user-specified end-entity certificates as user-specified CA’s for this purpose. As such, rehydrated certificates that ncdns generates will be considered valid, but nothing else will. (Unless you installed another user-specified CA on your machine that is valid for .bit. But if you did that, then either you want to intercept .bit, in which case it’s fine, or you did it against your will, in which case you are already screwed.)

I’ve implemented dehydrated certificate injection as part of ncdns for 2 major TLS implementations: CryptoAPI (used by Chromium on Windows) and NSS (used by Chromium on GNU/Linux). These are currently undergoing review as pull requests for ncdns. (The macOS trust store should also be feasible, but I haven’t done anything with it yet.) Right now, those pull requests prompt the user during ncdns installation with instructions for adding an HPKP pin to Chromium. (If you’ve tried out the ncdns for Windows installer on a machine that has Chromium, you might have noticed this dialog.) This isn’t great UX, and I’ve found a way to do this automatically without user involvement, which I will be implementing into the ncdns installer soon.

Unfortunately, abusing HPKP in this way isn’t an option in Firefox, because Mozilla’s implementation of HPKP doesn’t permit key pins to be placed on TLD’s. (As far as I can tell, the specifications seem to be ambiguous on this point.) Mozilla does offer an XPCOM API for HPKP (specifically, nsISiteSecurityService) that can inject key pins for individual .bit domains on the fly, but since XPCOM is deprecated by Mozilla, this is not a viable option as-is. On the bright side, Mozilla seems interested in implementing the API’s we need to do this in a less hacky way, so I’ll be engaging with Mozilla on this.

As another note: NSS trust store injection is rather slow right now, because I’m currently using NSS’s certutil to do the injection, and certutil isn’t properly optimized for speed. Sadly, there doesn’t seem to be an easy way of bypassing certutil for NSS like there is for CryptoAPI (NSS’s trust store is a sqlite database with a significantly more complex structure than CryptoAPI, and the CryptoAPI trick of leaving out all the data besides the certificate doesn’t work for NSS). I will probably be filing at least one bug report with NSS about certutil’s performance issues. If progress on fixing those issues appears to be unlikely, I think it may be feasible to do some witchcraft to speed it up a lot, but I’m hoping that things won’t come to that.

I’m hoping to get at least the CryptoAPI PR merged to official ncdns very soon, at which point I’ll ask Hugo to release a new ncdns for Windows installer so everyone can have fun testing.

ncdns for Windows Beta Installer Now Available

In order to facilitate the easy resolution of .bit domains, an installer for ncdns for Windows has been under development. This installer automatically installs and configures Namecoin Core, Unbound and ncdns.

An experimental binary release for this installer is now available. Interested Namecoin users are encouraged to test the installer and report any issues they encounter.

This release does not yet integrate the TLS integration support for ncdns under development by Jeremy Rand. This will be incorporated in a future release.

The development of this installer was funded by NLnet.

Reverse-Engineering CryptoAPI’s Certificate Registry Blobs

Every so often, I’m doing Namecoin-related development research (in this case, making TLS work properly) and I run across some really interesting information that no one else seems to have documented. While this post isn’t solely Namecoin-related (it’s probably useful to anyone curious about tinkering with TLS), I hope you find it interesting regardless.

A note on the focus here: while this research was done for the purpose of engineering specific things, I’m writing it from more of a “basic research” point of view. My dad’s career was in basic research, and I firmly believe that learning cool stuff for the sake of learning it is a worthwhile endeavor, regardless of what the practical applications are (and indeed, usually when basic research turns out to have applications, which is commonplace, the initial researchers didn’t know what those applications would be). Since I’m an engineer, there will be a bit of application-related commentary here, but don’t read this expecting it to be a summary of the next Namecoin software release’s feature set or use cases.

In Windows-based OS’s, most applications handle certificates via the CryptoAPI. CryptoAPI serves a somewhat similar role in Windows certificate verification as OpenSSL does on GNU/Linux-based systems. Notably, Mozilla-based applications like Firefox and Thunderbird don’t use CryptoAPI (nor OpenSSL); they use the Mozilla library NSS (on both Windows and GNU/Linux). However, except for Mozilla applications, and a few applications ported from GNU/Linux (e.g. Python) which use OpenSSL, just about everything on Windows uses CryptoAPI for its certificate needs. CryptoAPI is a quite old Microsoft technology; it dates back at least to Windows NT 4. (It might be even older, but I’ve never touched nor read about any of the earlier incarnations of Windows NT, so I wouldn’t know.) Like any other codebase that’s been around for over 2 decades, its design is somewhat convoluted, and my guess is that if it were being designed from scratch today, it would look very different.

CryptoAPI maintains a bunch of different stores for certificates. These stores are designated according to the certificate’s intended usage (e.g. a website cert, an intermediate CA, a root CA, a personal cert, and a bunch of other use cases that I don’t understand because I’ve never managed any kind of certificate infrastructure for an enterprise), the method by which the certificate was loaded (e.g. by a web browser cache, by group policy, and a bunch of other methods that, again, I don’t understand because I don’t do enterprise infrastructure), which users have permission to use the certs (roaming profiles have special handling), and even which applications are expected to consider them valid (Cortana, Edge, and Windows Store all have their own certificate stores, for reasons that I don’t understand in the slightest, although I do wonder whether adding an intercepting proxy to Cortana’s cert store would be useful in an attempt to wiretap Cortana and see what data Microsoft collects on its users). You can see a subset of the certificate stores’ contents via certmgr.msc, and there’s a command-line tool included with Windows called certutil which can edit or dump this data as well. Neither of these tools actually shows all of the stores, e.g. Cortana, Edge, and Windows Store are secret and invisible. Also, don’t confuse the CryptoAPI certutil with the Mozilla command-line tool also called certutil, which is similar but is for NSS stores and has an entirely different syntax.

Incidentally, CryptoAPI has some interesting behavior when it comes to root CA’s. If you add a self-signed website cert to a root CA store, that self-signed website cert becomes fully trusted (HSTS and HPKP even work, which implies that it doesn’t get reported as an override). Of course, this is usually a dangerous idea, since that self-signed website could then sign other websites’ certs – you did tell Windows to treat it as a root CA, after all. But Windows actually does respect the CA and CertUsage flags in this case: if you construct a cert that is not valid as a CA, Windows will happily let you add it to a root CA store, will accept it as a website cert, but will refuse to trust any other cert signed by that cert. Namecoin lead security engineer Ryan Castellucci told me on IRC that he’s not sure if this behavior is even defined in a spec, but in my testing, NSS seems to exhibit identical behavior (no idea about OpenSSL). Regardless of specs, Microsoft has a fanatical obsession with not changing behavior of any public-facing API that might impact backwards compatibility (to Microsoft, the original implementation is the spec), so I think it’s probably pretty safe to rely on this behavior, even when someone as thoroughly knowledgeable as Ryan has never encountered anything in the wild that does this. Of course, that’s just my assessment – I take no responsibility if this burns you. As they say on Brainiac: Science Abuse, “we do these experiments so you don’t have to – do not try this at home – no really, don’t.”

Now, unfortunately, CryptoAPI has a problem. It expects a user to have administrator privileges in order to add a cert to most of the stores. This is probably well-meaning, because you definitely don’t want some random piece of malware that abused a Javascript zero-day to be able to add a root CA, or anything like that. (Fun fact: any such malware can, however, add a root CA to Firefox, because the NSS cert stores are simply a file in your profile directory, and are therefore user-writeable. That’s even true for Firefox on many GNU/Linux systems, even though the OpenSSL store is protected.) Of course, the security benefits of requiring privileged access for this are dubious, given that malware running as the primary user can do all sorts of other mischief, such as replacing the shortcut to your browser with a patched version that MITM’s you. However, regardless of the alleged security benefit of this policy, there’s a fairly obvious problem here: this implies that if you want to run software that programatically adds root CA’s, perhaps for the use case in the previous paragraph, you need to give that software Administrator privileges. As a (minimally) sane person, running anything, much less a daemon that interacts with a bunch of untrusted network hosts (e.g. Namecoin peers), as an administrator is an absolute dealbreaker. Yes, I did code it that way as a proof of concept for the hackathon by the College Cryptocurrency Network that I got 3rd place in, but no way in hell am I going to ship software to end users that does such irresponsible things. And if you’re the kind of person who would be tempted to do that, please, for the sake of your users, exit the software development field before you get some dissident or whistleblower murdered. This stuff actually is important to those of us with ethics.

You might wonder: why the heck isn’t there a permission system for this? Coming from a culture that loves the concept (if not implementation) of things like AppArmor and SELinux, that was certainly my thought. But alas, I was unable to find any Microsoft documentation that suggested a way to delegate access to a specific cert store to some other user. (Of course, Microsoft’s documentation is a train wreck, so maybe they did address this use case and I just couldn’t find any mention of it.) However, I did learn something interesting by Googling. While OpenSSL cert stores are just a filesystem folder, and NSS cert stores are a database file (whose database backend is either BerkeleyDB or SQLite), CryptoAPI mostly uses… the Windows Registry. Remember, this is Microsoft, they dump their garbage in the registry with as little hesitation as petroleum companies dump their garbage in Latin-American rainforests. (Personal certificates that are part of roaming profiles are instead placed in a user’s profile folder, apparently ever since Windows 2000 came out. But almost everything else is in the registry.) Since the registry does have a permission system, this looks like the perfect solution.

It was relatively easy to figure out where these certificates are located in the dense, uncharted jungle that is the registry. Indeed, you can search your registry for keys titled Root and you’ll find all the root CA stores (the other types of stores are in sibling keys). Each certificate is located in its own subkey (the subkey is named based on the certificate’s SHA-1 fingerprint). Actually, let me digress for a moment. Why the hell is Microsoft using SHA-1 hashes as the names of registry keys, even in Windows 10? Yes, I know SHA-1 was not known to be weak when Microsoft designed CryptoAPI, but tying the name of something to a specific hash algorithm seems like a massively stupid idea in terms of design and safety. (And no, it’s not a good idea to drive drunk just because your crazy git uncle Linus does it every New Year’s Eve and hasn’t died yet.) Anyway, inside that subkey is a single value, called Blob, which contains binary data encoding the certificate. Not too complicated, right?

Oh, wait. We’re talking about Microsoft. Everything is complicated, usually for no discernable reason whatsoever. Also, the most complicated things usually have the least documentation. I know people who have long-ago adopted a policy of getting their Windows documentation from the ReactOS source code instead of the Microsoft website, because a small, minimally funded project that’s reverse-engineering everything writes more accurate documentation than the wildly successful company who actually engineered the system and wrote the original source code. Anyway, I looked at the contents of the binary blob in the registry, and noticed that it didn’t look right. More specifically, it wasn’t a DER-encoded x.509 structure, nor was it even PEM-encoded. Actually, there was a substring that did correspond to the DER-encoded x.509 structure, but there was a crapload of extra data too. For reference, it looked like this (in .reg format):

Windows Registry Editor Version 5.00


Just to see what would happen, I took a raw DER-encoded x.509 certificate and shoved it into the registry to see if CryptoAPI would accept it, but of course it didn’t, so I needed to figure out what that extra data was. Now, as a middle school student, as a high school student, and as an undergraduate student (though sadly not as a graduate student), I did a lot of reverse-engineering of various binary formats (making a Mega Drive Zero Wing ROM include custom dialogue between “Cracker” and “Admin” about how “All your 802.11b are belong to us” and that “You are on the way to DDoS” was a few days of work in 7th grade). So I was quite ready to go that route. However, I learned long ago that it’s always better to spend a few hours on Google to see if someone else has already done your dirty work for you, because usually someone has. So I did that.

The first result I found was a Microsoft mailing list thread from 2002 where Mitch Gallant and Rebecca Bartlett both inquired about this format. Microsoft’s response was to refuse to provide any documentation, and generally be rude and unhelpful, on the grounds that this use case was unsupported. Now, hang on, because I need to point something out. I’ve asked a lot of software vendors for obscure technical information about their products, nearly all of which were for unsupported use cases. By far my favorite vendor to work with in this area was the robotics hardware company Charmed Labs (they are incredibly nice and helpful, even happily giving me proprietary source code that was protected by patents, for me to do whatever I wanted with, as long as I didn’t distribute or use commercially). But generally speaking, the “good” companies’ responses to such requests follow this kind of formulation:

  1. What you’re trying to do is not something that we officially support.
  2. We think what you’re doing is a bad idea for these reasons.
  3. There may be other reasons that it’s a bad idea, which we haven’t thought of.
  4. We think the “right” way is something else, and we’re happy to help you with that method if you like.
  5. Regardless, here are all the answers to your questions.
  6. If you have any other questions about this unsupported use case, we’ll try to answer, as long as it doesn’t become a time sink for us. Don’t expect super-quick replies, because we’re looking up answers in our spare time.
  7. If any of the info we’re providing turns out to be incomplete or wrong, or you end up getting burned in any other way for doing this, we’re not responsible.

Whenever I’ve gotten a reply like this (and it’s happened reasonably often), I was a happy camper, because I was able to make an informed decision. Sometimes I decided to abandon my quest; other times I disregarded the warning and pressed on anyway. In the latter case, I knew full well what I was getting into, because the vendor had given me sufficient information and context for me to make up my mind. Usually, I was satisfied with my decision at the end of the day. In fact, I cannot remember a case where I did something I seriously regretted after being warned against it like that. I’m sure it could have happened, had the quantum noise been different, but if that had come to pass, I’m confident that I wouldn’t have blamed the vendor for giving me information coupled with advice that I ignored. There were several times where my disregard for the warning resulted in some lost development time or temporary confusion, but seriously, who could possibly be angry for the chance to gain practical experience in an unfamiliar area, particularly given that when I did decide to change course, I now had both the vendor’s expert recommendations and my new practical experience to inform my decision. What more could anyone want? My point is, the good software vendors treat their users like real, sentient people when they ask for information, while the bad software vendors (Microsoft included) treat their users the way that the owners of Number 4 Privet Drive treated their nephew up until mid-1991: Don’t ask questions!

Technically, Microsoft did provide parts (1) through (4) of the above form, but they don’t even qualify for partial credit here, because the reason they gave for (2) is atrocious on its face: once in 2 decades, they moved a store from the registry to the filesystem to handle roaming profiles, and anyone using the registry directly would have had to update their software (with a really minor change) once Windows 2000 came out. Frankly, if you’re unwilling to update your software once in 2 decades, I don’t know why you’re in this field, and you should go get a Ph.D. in Latin Literature so that you don’t need to ever learn anything new in order to stay at the top of your field for your whole life. Anyway, reading that thread was entirely unhelpful, except for the fact that it told me I had made a great choice never interviewing at Microsoft, because if I ever become the kind of tech support robot who shows up in that thread, someone please kill me.

So, I continued to look through Google for a while. And I did find two people who had actually tried to reverse-engineer the blob format. Tim Jacobs had posted some information in 2008, and Willem Jan Hengeveld had posted some other info in 2003. Interestingly, both Tim and Willem had been looking into dealing with bugs in mobile versions of Windows that made it hard to import a certificate any other way. (See, basic research has diverse, and often non-obvious, use cases.) Tim’s documentation wasn’t particularly helpful for me, because while it explained how to solve a specific problem (which wasn’t the problem I had), it didn’t really explain why that solution worked, nor how he figured it out (actually, I’m very skeptical of why his solution even works, and based on my research below, I suspect that he simply got lucky and that his method will spectacularly break in many real-world scenarios). However, Willem’s documentation was very helpful. According to Willem, a cert blob is a sequence of records, each of which consists of a 4-byte propid (which I gather means “property ID”), a 4-byte unknown value (which I assume is reserved by Microsoft for future expansion, since everything I encountered used exactly the same value), a 4-byte size, and then the raw data for that property (whose size in bytes was specified by the size field). Willem also listed the common property ID’s that show up.

There was just one problem: the blob I was looking at had a bunch of property ID’s that weren’t in Willem’s list. So, of course, I Googled for one of the property ID’s that was in Willem’s list, and I ended up finding this page and this page on the Microsoft website, which had a (mostly) complete list. Except… those references had descriptions (which, admittedly, is nice) but not any info on what numerical values the property ID’s were. However, they did include a reference to Wincrypt.h. Ah ha, I thought, I’ve done this before! So I went and looked up that header file in the MinGW source code, and was treated to a complete list of the numerical values of all the property ID’s.

From there, I started gathering a list of which property ID’s Windows seemed to be using, so that I could generate the appropriate information while inserting a cert, given only its DER x.509 encoding. Unfortunately, quite a lot of the property ID’s were for things that looked quite annoying to calculate. After trying to figure out a way to calculate a “signature hash” of an x.509 cert in Golang, and not having any fun whatsoever (mind you, I did find ways to do it, I just knew I would despise the process of coding it, and of ever looking at the horrible code that was bound to result), a thought crossed my mind: What does CryptoAPI do if some of the properties are missing from the blob, as long as the record format is correct? So, I took the blob that Windows had generated, and I wiped everything except for the x.509 cert itself and the 12-byte header for that property. I inserted it into the registry, and visited the corresponding website in Chrome. The website loaded just fine! Then I went back to the registry editor, and refreshed, and was quite surprised to see that the moment that CryptoAPI had validated the cert, it had re-calculated all of the other missing fields, and inserted them into the registry.

So, basically, all of those other properties are, as best I can tell, just an elaborate caching mechanism, completely superfluous for proper operation. Microsoft made CryptoAPI substantially more complex, added at least 4 public-facing API functions (those are just the ones I accidentally ran across), and invented a custom, undocumented binary blob format, all so that they could avoid doing a couple of extra hash operations when verifying a chain that included a previously seen certificate. (Remember, hash operations are fast, while RSA and ECDSA, which aren’t cached here and are still needed to verify cert chains, are slow.)

Typical Microsoft. slow clap

Thanks goes to ncdns developer Hugo Landau and Monero developer Riccardo Spagni for keeping me company on IRC while I figured all of the above out. What does this have to do with Namecoin? You’ll find out in my next post.

Progress on ncdns-nsis

Development nears completion on the NSIS-based Namecoin and ncdns bundle installer for Windows.

The ncdns-nsis repository provides source code for an NSIS-based installer which can automatically install and configure Namecoin Core, ncdns and Unbound and configure name resolution of .bit domains via Unbound.

The installer can install Namecoin Core and Unbound automatically, but also allows users to opt out of the installation of these components if they wish to provide their own.

Completion of the ncdns-nsis installer project will enable the Namecoin project to distribute a Windows binary installer providing a turnkey, configuration-free solution for .bit domain resolution. The installer is also intended to support reproducible builds and can be built from a POSIX system.

At this point, extensive testing is the primary work remaining on the completion of the ncdns-nsis installer.

Namecoin Receives Funding from NLnet Foundation’s Internet Hardening Fund

We’re happy to announce that Namecoin is receiving 29,895 EUR in funding from NLnet Foundation’s Internet Hardening Fund. If you’re unfamiliar with NLnet, you might want to read about NLnet Foundation, or just take a look at the projects they’ve funded over the years (you might see some familiar names). The Internet Hardening Fund is managed by NLnet and funded by the Netherlands Ministry of Economic Affairs. The funding will be used to fund 4 Namecoin developers (Jeremy Rand, Hugo Landau, Brandon Roberts, and Joseph Bisch) to produce a usable decentralized TLS public key infrastructure.

Specifically, the following areas of development will be funded:

  • Integration with DNS functionality of major operating systems. We intend to support GNU/Linux and Windows, including DNS integration for Tor. Other operating system support may be developed if things go well.
  • Integration with TLS certificate validation functionality of major web browsers. We intend to support Chromium, Firefox, and Tor Browser on GNU/Linux and Windows. Other browser support may be developed if things go well.
  • Improvements to the lightweight SPV name lookup client.
  • A lightweight SPV wallet with name support. We intend to use Electrum.
  • Wallet GUI improvements, including Coin Control for name transactions and a name update GUI that doesn’t require knowing JSON.
  • Improved installation automation. We intend to provide a Windows installer that includes a Namecoin client, DNS integration, and TLS integration. Other OS support may be developed if things go well.

We’d like to thank the awesome people at NLnet Foundation for selecting us for this opportunity, as well as the Netherlands Ministry of Economic Affairs for recognizing that a hardened Internet is worth receiving government financial support.

We’ll be posting updates regularly as development proceeds. (Spoiler alert: a few components are already nearly ready for beta releases.)

ICANN58 Summary

As was announced, I represented Namecoin at ICANN58 in Copenhagen. Below is a brief summary of how it went.

  • I presented in the Emerging Identifier Technology Panel.
  • I presented in the Technical Experts Group / Board Joint Meeting.
  • A significant number of people in the ICANN community are interested in Namecoin.
  • While I have not attended previous ICANN events and therefore cannot evaluate this myself, my understanding is that the EIT panel session had an unusually large audience.
  • There is skepticism in the ICANN community of Namecoin’s ability to completely replace the DNS.
    • By far the most common reason for this skepticism is the concern that Namecoin may not be able to scale to DNS’s usage levels.
      • I fully agree that this is a good reason to be skeptical and that work needs to be done in this area.
    • Another concern raised was Namecoin’s lack of privacy in its current form (specifically the risk of transaction graph analysis).
      • The people who raised this concern appear to be satisfied that the Namecoin developers understand that this is a problem and that we intend to fix it. If we fail to fix it adequately, this concern is likely to become more of a big deal.
  • The ICANN community appears to be reasonably accepting of Namecoin’s role as an alternative to DNS; Namecoin makes different tradeoffs from DNS, is therefore likely to be optimal for a different userbase, and can co-exist with DNS in its current state.
  • Several people I met are interested in assisting Namecoin; we are following up with those people.
  • I ran out of business cards in my wallet 3 times in 3 days. Luckily, I carry a large stash of business cards with my travel laptop, so everyone who requested my business card received it.
  • My wallet is currently sufficiently full of business cards from ICANN58 attendees that I’m having trouble easily fitting my credit card into my wallet.
  • The joint meeting of ICANN’s Security and Stability Advisory Committee (SSAC) and the ICANN board included a segment on Special-Use Names and name collisions. For those who are unaware, this is of interest to Namecoin because it would be problematic for Namecoin if ICANN were to allow someone to purchase .bit as a standard DNS TLD.
    • Free-software-friendly video recording is hosted by
    • The above recording is converted from ICANN’s official Adobe Connect video recording. Copyright ICANN; used with permission.
    • The discussion of collisions between non-DNS names (such as Namecoin, though Namecoin wasn’t explicitly mentioned) and DNS names (such as if ICANN were to issue the .bit TLD to someone) begins at timestamp 42:25. I highly recommend watching the full segment, but some highlights include:
      • The SAC090 document “SSAC Advisory on the Stability of the Domain Namespace” was cited; most important are 3 Recommendations from SSAC (summarized by Jeremy, apologies for any errors):
        • Recognize that name collisions will always be with us, and they’re not going to go away. There’s no way to control how people use names.
        • It’s important to control the things that you can control: make sure that the parts of the namespace that ICANN controls are predictable (harmonize with private-use names). We need to allow private-use names to exist, in the spirit of innovation.
        • Since we recognize that we are not the only ones who have names that will look like TLD names, and the community is going to use that kind of stuff in an interesting way, we need to have procedures for dealing with other bodies who are going to be creating special-use names for their own purposes. It is important to establish regular communication, how we each recognize each other, how we’re going to work together, and set ourselves up for potentially others (besides IETF) who may want to create lists of names. Be prepared to deal with other groups who are going to have their own lists of names.
      • Steve Crocker (chair of the ICANN board) said the following:

        The IETF has a special names list, a reserved names list, but my understanding is that that’s not a definitive list in the following sense. It takes a while before a name gets onto that list. So, it tends to be on the conservative side. There are other names that are in use but have not gone through an IETF process. From where we’re sitting over at ICANN, if we want to be conservative, we would take into account not only the names on the reserve list from the IETF but also other names where it’s evident there is usage but nobody has come along and said we’re going to – you should reserve this and reserve this and so forth. So, I would think that our obligation is to have a somewhat wider field of view, including not only the official list but also what’s actually happening in the real world. And I can anticipate arguments that say well, there’s no official reason to reject this name [for ICANN issuance, e.g. someone buying the .bit TLD for non-Namecoin use], therefore you must accept it. I would say just the opposite, that we have an obligation to be careful, and if we see reasons why a name should not be allocated, then we have that authority, we have that obligation to do that and to err on the side of caution there.

    • I consider this an extremely good sign.
  • In response to a question in the Public Forum 2 about whether ICANN was looking into adopting Namecoin, Steve Crocker (chair of the ICANN board) commented “These things take time.” The full question and answer are in the ICANN transcript, pages 25-28. Steve’s comment is, in my opinion, a completely reasonable response.
  • We plan to continue engaging with the ICANN community.
  • We plan to continue engaging with IETF on Special-Use Name registration.
  • At this time, I have no reason to expect any hostile action by ICANN toward Namecoin.

As with other conferences, I won’t be releasing details of private conversations, because I want people to be able to talk to me at conferences without being worried that off-the-cuff comments will be publicly published. That said, all of the private conversations I engaged in were highly encouraging.

Huge thanks to David Conrad (ICANN CTO) for inviting me to attend ICANN58, and to Adiel Akplogan (ICANN VP of Technical Engagement) for inviting me to the EIT Panel. Also thanks to ICANN for covering my travel expenses. I hope we can do this again sometime.

QCon London 2017 Summary

As was announced, I represented Namecoin at QCon London 2017. Below is a brief summary of how it went.

The theme of the blockchain track was “Beyond the Hype”. As such, the presentations in the track primarily focused on all the things that can go wrong when using a blockchain. Riccardo Spagni (AKA fluffypony of Monero) is definitely an ideal person to host this track. My talk was on alternate blockchains, with a focus on Namecoin (and some Monero). In the spirit of going “Beyond the Hype”, my talk was almost entirely about things that can go wrong when using a non-Bitcoin blockchain.

I think this is a very important theme for a blockchain track, because the hype attached to the blockchain field is seriously problematic for our field’s credibility. None of us were there to sell our technology, attract investors, or grab media attention – we were there to provide a reality check for an audience who, in large part, had minimal exposure to blockchain technology and wanted to learn more about what use cases it’s good or bad for.

Lots of attendees talked with me over dinner and in the hallway, and I’ll be following up with them ASAP. After QCon, I attended a talk Riccardo gave at Imperial College; several people there were interested in Namecoin. I met up with Riccardo the next day to discuss lots of cool stuff involving Namecoin and Monero.

As with other conferences, I won’t be releasing details of private conversations, because I want people to be able to talk to me at conferences without being worried that off-the-cuff comments will be publicly published.

Huge thanks to Riccardo for inviting me, and to all the QCon conference organizers for an awesome conference (and for covering my travel expenses). It’d be awesome if we can do this again.

A video of my talk is scheduled for release on June 26, 2017.

Namecoin Core 0.13.99-name-tab-beta1 Ready for General Use

Namecoin Core 0.13.99-name-tab-beta1, which has been listed on our Beta Downloads page for a few months, has demonstrated itself to be stable enough that it is now listed on the main Downloads page. Huge thanks to our Lead C++ GUI Engineer Brandon Roberts for his work on this.

Namecoin’s Jeremy Rand will be a speaker at ICANN58

ICANN has invited a Namecoin developer to speak at the ICANN58 meeting on March 11-16 2017 in Copenhagen, and I’m happy to say that I’ve accepted their invitation. Since I’m well aware that this may be surprising to some readers, I think it’s beneficial to everyone to announce it here, and give some details about why I’ll be attending.

The rest of this post will be in the excellent Q&A-style format.

Why did ICANN invite you?

To my understanding, I was invited because of a perception that there was a lack of understanding and dialogue between ICANN and Namecoin about specifically what the goals of each group were. The hope is that by encouraging discussion between ICANN and Namecoin, the groups will have a more accurate idea of what the other is doing and what common interests we might have.

It’s not news to me that ICANN has an interest in Namecoin; an ICANN panel report favorably mentioned us. However, I admit that I was (pleasantly) surprised to receive this invitation.

What do you think of ICANN and DNS?

To be totally honest, I’m not really very knowledgeable about how ICANN operates. I hope to gain some knowledge on this subject at the meeting. That said, I’ve heard that ICANN has some political issues. (Indeed, if James Seng’s comments in the aforementioned report are any indication, this is a recognized issue by ICANN participants, not just from the outside.) This is really not surprising, and as far as I know, it’s not due to any kind of nefarious motivation by ICANN or any people within ICANN. My take is that ICANN’s political issues are likely to be simply because ICANN is very large, and large centralized entities are inevitably going to have political issues. If, in an alternate reality, OpenNIC were wildly successful and ended up as large as ICANN is today, I predict that OpenNIC would end up with political issues too.

Isn’t that just ICANN’s own fault for being centralized?

That’s not ICANN’s fault, it’s the reality of the laws of math. When DNS and ICANN were created, everyone believed that decentralized global consensus was impossible (and this belief was well-supported by a proof by Lamport dating back to the 1970’s). It wasn’t until Satoshi Nakamoto invented Bitcoin that anyone had any credible reason to believe that decentralized global consensus was solvable, and it wasn’t until Appamatto and Aaron Swartz proposed BitDNS and Nakanames 2 years later that anyone really seriously considered applying a Nakamoto blockchain to a DNS-like system.

But Namecoin exists now; doesn’t that make DNS obsolete?

Not really. Namecoin makes a number of design tradeoffs in order to achieve decentralization. Compared to DNS, Namecoin has significantly worse security against run-of-the-mill malware, significantly worse privacy against your nosy friends/neighbors/employer, and significantly worse resistance to squatting and trademark infringement, to list just a few. These are open research problems for Namecoin-like systems, whereas DNS has long ago solved them. I work on Namecoin because Namecoin also has some advantages over DNS, and I think there is a significant user base who want those advantages enough that they are willing to cope with the downsides. But that doesn’t mean that DNS is obsolete, or that I expect Namecoin to replace DNS anytime soon. If, in the future, Namecoin eventually solves those open research problems, and as a result replaces DNS, that’d be cool as heck from my point of view, but if that ever happens, I think it will be far enough in the future that it’s not worth worrying about right now.

Namecoin has almost no funding; if you had the budget of the DNS industry, wouldn’t those open research problems have been solved by now?

That would be inconsistent with the definition of “open research problem”. Funding would certainly help us spend more time tackling those problems, but there’s no guarantee that the problems are even solvable. Also, since no one is offering to give us such a budget, there’s not really much point in speculating here.

Are you being paid to attend?

ICANN is covering my travel expenses. (Naturally, I wasn’t going to ask NMDF to pay for me to travel. We don’t have anywhere near enough funding for that.) Other than that, I’m not being paid to attend.

Has ICANN asked for any control or influence on Namecoin?

Of course not. (And if they did, I would decline – as I assume would the other devs.) It’s entirely standard to talk to people working on related projects; it doesn’t imply any desire to influence or control those projects.

Are you concerned that this will be spun by market manipulators as some kind of sell-out?

I’m reasonably confident that market manipulators will try to profit by spinning this in some way, but that’s not anything new. We’ve already seen market manipulators try to make money by alleging a sell-out, based on everything from our application to Google Summer of Code in 2014 and 2015, to me getting a college scholarship from Google in 2013, to our collaboration with GNUnet, I2P, and Tor to try to register the .bit TLD as a special-use name via IETF. Those same market manipulators will, I assume, use this the same way, probably with the same minimal level of success that they had previously.

If I had any interest in spending my time worrying about market manipulators, I’d be in a different line of work, making way more money than I’m making right now. The best I can do is be transparent about this, so that it’s obvious to anyone who does an ounce of research that nothing nefarious occurred. Transparency FTW.

Will you publicly post your presentation slides?

Sure, why not?

Namecoin’s Jeremy Rand will be a speaker at QCon London 2017

As a result of an invitation from Riccardo Spagni (AKA fluffypony of Monero), I will be speaking at the “Practical Cryptography & Blockchains: Beyond the Hype” track at QCon London 2017 (March 6-8 2017). My talk is entitled “Case Study: Alternate Blockchains”. I will also be on a panel discussion alongside Paul Sztorc, David Vorick, Elaine Ou, Peter Todd, and Riccardo Spagni.

My understanding is that a video of my talk will be published by QCon. Assuming that that’s correct, I will post a link here when it’s available.

Huge thanks to Riccardo for inviting me, and to the QCon organizers for putting on the conference and covering my travel expenses. Looking forward to it!

Lightweight SPV Lookups: Initial Beta

If you watched my lightning talk at Decentralized Web Summit 2016 (and if you didn’t, shame on you – go watch it right now along with the other talks!), you’ll remember that I announced SPV name lookups were working. I’m happy to announce that that code is now published in preliminary form on GitHub, and binaries are available for testing.

You can download it at the Beta Downloads page. Once installed, it’s basically a drop-in replacement for Namecoin Core for any application that does name lookups (such as ncdns). Test reports are greatly appreciated so that we can do a proper release sooner.

Initial syncup using a residential clearnet cable modem connection takes between 5 minutes and 10 minutes, depending on the settings. (It is probably feasible to improve this.) Lookup latency for name_show varies from 2 seconds to 4 milliseconds, depending on the settings. (It is also probably feasible to improve this.)

This work wouldn’t have been possible without the work of some very awesome people whom I need to thank.

First, I need to thank Ross Nicoll from Dogecoin (warning: non-TLS link) for creating libdohj, an altcoin abstraction library that has prevented Namecoin from needing to maintain a fork of BitcoinJ. We’re using the same AuxPoW implementation from libdohj that Dogecoin is using – a fitting repayment, since Dogecoin Core uses the same AuxPoW implementation that Daniel Kraft wrote for Namecoin Core. We look forward to continuing to work with Ross and the other excellent people at Dogecoin on areas of shared interest.

Second, I need to thank Sean Gilligan for his work on bitcoinj-addons, a collection of tools that includes a JSON-RPC server implemented using BitcoinJ, which can substitute for Bitcoin Core. Sean is also a big Namecoin enthusiast. (I also finally got to meet Sean in person at DWS.)

Last but not least, I need to thank Marius Hanne, operator of the block explorer. The SPV lookup client currently is capable of using for extra efficiency (either for checking the height of blocks to download over P2P, or for downloading merkle proofs). Marius has been incredibly helpful at customizing the API for this purpose. is under a free software license (AGPLv3), so you can run your own instance if you like.

Remember: this is a beta, for testing purposes only. Don’t use this for situations where incorrect name responses could lead to results that you aren’t willing to accept.

In addition, some notes about security. SPV protects you from being served expired name data, and protects you from being served unexpired name data that isn’t part of the longest chain. However, the SPV modes other than leveldbtxcache (see the documentation) don’t protect you from being served outdated name data that hasn’t yet expired, nor does it protect you from being served false nonexistence responses, nor does it protect you from someone logging which names you look up. We made an intentional design decision to trust here, rather than the Namecoin P2P network, because the P2P network is unauthenticated, trivially easy to wiretap, and trivially easy to Sybil. leveldbtxcache mode avoids these isues, although it takes about twice as long to synchronize. We have plans to add further improvements in these areas as well. SPV also doesn’t protect you from attackers with a large amount of hashpower. As with Bitcoin, a major reason that miners can’t easily attack end users is because there are enough full nodes on the network to keep the miners honest. If you have the ability to run Namecoin Core (syncup time of a few hours, and a few GB of storage), you should do so – you’ll have better security for yourself, and you’ll be improving the security of other users who can’t run a full node.

Have fun testing!

Decentralized Web Summit Recap

As was mentioned on the forum and /r/Namecoin, I represented Namecoin at the Decentralized Web Summit at the Internet Archive in San Francisco, June 6 - June 10. Lots of awesomeness occurred.

I participated in a panel on naming and identity systems on Wednesday. Other panelists were Christopher Allen (Blockstream), Muneeb Ali (Blockstack), and Joachim Lohkamp (Jolocom); Chelsea Barabas (MIT Center for Civic Media) moderated. The panel had a diverse set of perspectives, and I think the discussion was informative.

On Thursday, I did a lightning talk. The talk briefly introduced Namecoin, and then went on to new developments, specifically new announcements about HTTPS and SPV. The lightning talk concluded with an invitation to talk to us about collaboration, and a plug for my workshop (which immediately followed).

The workshop was basically an intro to actually using Namecoin. I walked the attendees through registering domain names and identities, viewing domain names with ncdns, and logging into websites with NameID. We had some minor technical issues during the workshop (which is to be expected), but nothing too bad. At the end of the workshop, I showed a demo of the TLS code working. (Major thanks go out to fellow Namecoin developers Brandon Roberts, Jonas Östman, Joseph Bisch, and Cassini for helping me put together the workshop.)

But of course, I didn’t fly to San Francisco just to do a panel, lightning talk, and workshop. A major goal was to talk to as many other projects as possible to see where we could collaborate. (No single project is going to decentralize the entire Web, but working together, we might have a shot.) I won’t list all the conversations I had on this post, because I want people to be able to talk freely to me at conferences without being worried that the conversation will be posted for the world to see, but the number of orgs I talked to stands at at least 23. Hopefully we’ll be able to announce some results of these conversations in the near future.

And of course, it wouldn’t be an event by the Internet Archive without archived videos, so here are some of the highlights that Namecoiners will find particularly interesting:

Lightning Talk: Jeremy Rand of Namecoin

Builder’s Day Interview: Tamas Kocsis of ZeroNet (uses Namecoin)

Lightning Talk: Tamas Kocsis of ZeroNet (uses Namecoin)

Naming and User Identities Panel

Overall, it was an excellent event. I highly recommend watching all the other non-Namecoin content as well: full archives of all the talks are here.

I also want to thank Brewster Kahle and Wendy Hanamura for organizing the summit, and Kyle Drake of Neocities, Greg Slepak of okTurtles, and John Light of Bitseed for inviting me to attend. Also thanks to all the other organizers, speakers, and attendees: you’re all awesome. I really hope that Internet Archive makes this a regular event.

NMControl 0.8.1

UPNP Vulnerability in Bitcoin Core affects Namecoin

A vulnerability was found in Bitcoin Core. It allows an attack from malicious peers in the local network via UPNP. Namecoin is affected, too, so everybody should turn off UPNP until further notice.

OneName’s Blockstore is much less secure than Namecoin

Note: the naming system described in this post, Blockstore, is now named Blockstack.

It’s well-known that OneName has been engaged in questionable practices on the Namecoin blockchain, such as creating a duplicate namespace (u/) which harms the security of users and aids squatters. So we were interested to hear the news on September 12 that OneName has decided to stop using Namecoin in favor of a naming system they announced circa February 2015, Blockstore. Blockstore stores name transactions within OP_RETURN outputs on the Bitcoin blockchain (the full values of names are stored in a DHT). OneName claims that Blockstore has better security than Namecoin, on the grounds that Bitcoin hashpower is larger and more decentralized than Namecoin’s. This is a false assumption.

It is fairly well-known that a blockchain is a dynamic-membership multiparty signature (DMMS), attesting to the correctness of the transactions. Specifically, there are two main types of correctness that the blockchain attests to: the ordering of the transactions, and the validity of the transactions with regard to all previous transactions. Correctness of ordering is primarily to prevent double-spending of otherwise-valid coins. Transaction validity, such as checking ECDSA signatures and making sure that names are being spent by their rightful owner, allows SPV-based clients to function properly (among other things). OneName is claiming that Bitcoin’s blockchain is a DMMS attesting to Blockstore’s correctness. But the Bitcoin miners are only verifying ordering and Bitcoin transaction validity – they are not verifying the validity of Blockstore transactions.

Is this a big deal? Yes. It means that if you wrote an SPV client for Blockstore, I would be able to create an OP_RETURN output in the Bitcoin blockchain that claimed ownership of any arbitrary name, and your SPV client would not be able to detect the fraud. It also means that a validating Blockstore node cannot be a UTXO-pruned Bitcoin client – a full Bitcoin client is needed.

To expand further on this issue, in the event of malicious data insertion by users bent on disrupting the system, clients that are asking for data from Blockstore servers have almost no way to verify whether the servers are telling the truth or not.

In Bitcoin, the notion of SPV clients was proposed by Satoshi as a way for lightweight clients to avoid the need to store the entire Bitcoin blockchain themselves. As part of this idea, Satoshi described a mechanism by which fraud proofs could be used to reveal cheating and, ostensibly, punish the cheaters. Bitcoin SPV is in large part enabled by the proof-of-work in Bitcoin which makes forging SPV responses very difficult to begin with. In Blockstore’s system, lightweight lookups have no PoW-backing, and there does not appear to be a way to have even simple Satoshi-style PoW-based fraud proofs to detect cheating, so clients are likely entirely at the mercy of anyone running a server. Blockstore-specific SPV fraud proofs would require complex mechanisms and probably extensive pathing hints, and since fraud proofs don’t even exist yet in Bitcoin (wherein the majority of blockchain research and development is happening and on which the attention of nearly all of the interested cryptographers, research scientists, developers, and engineers is focused) it is unlikely Blockstore can satisfactorily solve this particular problem given the more extreme constraints they are operating with.

The Blockstore system is analogous to recommending that currency be stored in a blockchain that has a higher hashrate than Bitcoin and has 100 equally sized pools, but whose block validation rules are so loose that signature verifications always pass. What’s the point when I can steal your money or names and your client can’t tell? (Of course, when all signature verifications pass, even double-spend detection can’t function either, so this doesn’t even solve double-spends.)

Namecoin, in contrast, enforces transaction validity (including name ownership) in blockchain validation rules. This means that, even if a majority of Namecoin hashpower wanted to steal your name, their transaction that spends your name coin would be rejected by all of the network’s validating nodes. They could double-spend a name, but the only attack that this enables is fraud during non-atomic name trades. Given that Namecoin supports atomic trading of a name for currency (see ANTPY and NameTrade), this attack is unlikely to be an issue.

A prolonged 51% attack on Namecoin could censor name transactions and eventually cause names to expire if the attack lasted 8 months, but this would be detectable and obvious to all users on the Namecoin P2P network. (Moreover, as soon as the attack started, it would be detectable and obvious specifically which names were targeted, and if the names were re-registered by the 51% attacker, they would be distinguishable from the original name by the block height of their corresponding name_firstupdate transaction. We have a pending proposal to make that block height visible to user applications so that such attacks can be automatically mitigated.) And of course, a mining pool who performed an 8-month-long 51% attack would most likely lose a lot of hashpower as their users abandoned them in favor of mining pools who aren’t attacking the network.

Is Namecoin’s mining centralization problematic? Yes, to a point. But with Namecoin there is a possibility for the situation to improve in the foreseeable future with the new Namecoin Core client, and with influx of new users and miners due to improved usability. While Namecoin currently has around 40 percent of Bitcoin’s hashpower verifying transaction validity, Blockstore has 0.

Additionally, DHT-based discovery of storage nodes is one of the classic suggestions of new users as an alternative to DNS seeds, and, originally, IRC-based discovery: it has never been committed because it is trivial to attack DHT-based networks, and partly because once a node is connected, Bitcoin (and thus Namecoin) peer nodes are solicitous with peer-sharing.

As an actual data store, DHT as it is classically described runs into issues with non-global or non-contiguous storage, with little to no way to verify the completeness of the data stored therein. With the decoupled headers in OP_RETURN-using transactions in Bitcoin and the data storage in a DHT (or DHT-like) separate network, there is the likelihood of some little-used data simply disappearing entirely from the network. There is no indication of how Blockstore intends to handle this highly-likely failure condition.

More interesting are Bitcoin-related failure conditions: Blockstore information is not in an obscured Merklized tree-like structure with the root node stored in Bitcoin; Blockstore proposes to store actual raw data in OP_RETURN, with the limited space therein necessarily requiring highly constrained bits of data and limits in its form and structure. With this, it would be trivial for anti-spam mining cabals to censor these transactions, and given the understandable hostility with which some Bitcoin advocates treat altcoin bloating of the Bitcoin blockchain, the inevitable result will be a mass-distributed method of censoring of Blockstore transactions. Even if this is not so, it is a systemic flaw and therefore at permanent risk of being disrupted by miners who choose not to enable what they in turn view as the hostile economic externalities involved with permanent storage of questionably valuable data on behalf of third parties. As Satoshi noted: “Piling every proof-of-work quorum system in the world into one dataset doesn’t scale.”

Finally, one of the biggest flaws in this scheme is the nature of the loosely-connected graph structure formed by the so-called “consensus hash” that Blockstore hand-waves away by saying it will hash the data in the “last 12 blocks” without a concrete description thereof. What algorithms do they propose to ensure that not only does it form a properly, fully-connected graph and is verified, but also that its consensus-hash is accurate or even useful? Graph algorithms are notoriously complex: entire branches of science exist just to study and theorize about them. What use is this consensus hash when it’s entirely voluntary and arbitrarily-connected to prior data? How is the verification process going to proceed without, over a long period of time, becoming so complex that the cost is no longer feasible for normal consumer processors? How does Blockstore intend to discover what data each consensus hash even refers to? Transitive closure searches for such graphs could be made arbitrarily complex and non-deterministic by attackers who are interested in doing so, especially over time, and there is no mention of this class of vulnerability nor its proposed solution by Blockstore.

We will be working on improving Namecoin identities to make pseudo-decentralized naming systems obsolete. But unlike the commercial enterprise OneName, we are volunteers creating ethical software in our spare time. If you prefer our method of prioritizing sound design over flashy PR campaigns, join us!

Why Duplicate Namespaces Are Bad for Users

Every now and then, we’re approached by users who are asking about namespaces which duplicate functionality of the officially recommended namespaces. Examples of these namespaces include tor/, i2p/, and u/. We think these duplicate namespaces are harmful to end users. This blog post will try to explain why duplicating functionality of existing namespaces is almost always a bad idea.


This whole thing seems to have started when someone noticed that the d/ specification, which is used for domain names, only supported IP addresses. This person thought it would be awesome to have DNS for Tor hidden services, and proposed a tor/ namespace for such domains. Someone else appears to have decided the same thing for I2P, and created an i2p/ proposal.

An alternative proposal was the d/ 2.0 spec, which allowed d/ names to map to Tor hidden services and I2P eepsites. This is the proposal which is for the most part still widely used today.

Why was d/ 2.0 a better idea than starting 2 new namespaces?

Duplicate Namespaces Attract Squatters

Imagine that d/, tor/, and i2p/ are all common namespaces. Let’s say that WikiLeaks is running an IPv4-based website using the name d/wikileaks. Now let’s say that WikiLeaks wishes to offer a Tor hidden service for their website. They now have to register a second name, tor/wikileaks. Uh oh, seems a squatter saw that WikiLeaks had d/wikileaks and preemptively grabbed tor/wikileaks and i2p/wikileaks just in case WikiLeaks wanted those names. Now WikiLeaks has to negotiate with a squatter, who potentially might be on the payroll of a government who wants to either cost WikiLeaks lots of money or impersonate it.

What’s the defense here? The only defense is to preemptively register your name in all namespaces, just in case you want them later.

Let’s say that in an alternate reality, WikiLeaks did exactly this, registering d/wikileaks, tor/wikileaks, and i2p/wikileaks. Now let’s imagine that someone decides that CJDNS mesh networking would be nice to have with Namecoin’s domain names, and creates a cjdns/ namespace. Well crap, now WikiLeaks is in a race with squatters to see who can grab cjdns/wikileaks first; if WikiLeaks fails, then they can’t ever use their name with CJDNS.

Remember that the domain squatters probably expend much more time watching namespace proposals, since that’s basically their job. WikiLeaks, on the other hand, probably is more worried about their whistleblower anonymity infrastructure than their choice of Namecoin namespaces.

This is simply a losing game for everyone except squatters.

Duplicate Namespaces Break Users’ Security Assumptions

Imagine a situation where an end user hears from a trusted source that wikileaks.bit is a great place to submit documentation of government corruption. wikileaks.bit uses the d/ namespace. But the end user doesn’t want to use clearnet, so she uses the tor/ namespace instead, accessing the domain wikileaks.tor. Note that she has just made the assumption that d/wikileaks and tor/wikileaks are operated by the same entity. However, this is not the case. The Namecoin network considers those two names to be entirely different things. Imagine that tor/wikileaks is instead operated by a government agency (perhaps they bought it from a squatter). Now our whistleblower is screwed.

If duplicate namespaces are in use, the only way to verify that two names are controlled by the same entity is to inspect the name you trust, and see if it links to the other name. For example, you could visit the website associated with d/wikileaks, and see if it mentions tor/wikileaks. This, of course, is neither automatable nor secure in our whistleblower’s case. Given how popular and successful phishing is, providing scammers with an easy way to break users’ security assumptions is an extremely bad enginering idea.

Consolidate All Namespaces with Common Use Cases

Let’s look instead at the d/ 2.0 proposal. It recognized that IP-based DNS, Tor-based DNS, and I2P-based DNS are all aiming at a common use case. By creating new functionality as new fields of the d/ namespace rather than new namespaces, the proposal makes sure that users of Namecoin DNS will be able to freely switch between IP, Tor, I2P, and any future system which may come along, without ever needing to register a new name. This protects users from squatters and protects their security, both now and in the future. (It also saves them money on name fees.)

Your Options When a Namespace Spec Doesn’t Meet Your Needs

Let’s say that you want to implement a new feature into an existing use case in Namecoin. For example, maybe you wish the id/ spec had some extra fields. You have three options:

  1. Talk to the other Namecoin developers and propose a change to the spec. This is what we generally recommend, although we realize that in some cases this may be difficult if your project is confidential prior to launch.
  2. Add a custom field to an existing namespace spec. As long as your new field has a name which isn’t likely to collide with other use cases, this is pretty much harmless (although we’d love it if you talked to us). Even if you’re refactoring existing features, it is likely that software following the existing spec will ignore your extra fields, and you can ignore the preexisting spec’s fields. This means that the two schemes can co-exist pretty much peacefully.
  3. Make a new namespace for your specific fields, and disregard the existing namespace. This is harmful; there is almost never a good reason to do this.

The u/ Namespace: Exactly How Not to Approach the Problem

As far as we can tell, a for-profit company (whom we won’t name here) decided to start offering identity products using the Namecoin blockchain. They didn’t like the structure of the id/ spec. So, did they talk to us? Nope, we never heard of their product until after it launched (we first noticed their product because of a bunch of nonstandard names showing up in the blockchain). Did they add some custom fields to id/? Nope, they instead did the worst possible thing as listed above: they made their own namespace (u/) with identical use cases as the pre-existing id/.

The Squatting Argument Revisited

While we’ve had difficulty reaching the team behind u/ for an official statement, we are under the impression that one of their stated rationales for creating a new namespace was that id/ was allegedly squatted too much. This is a quite strange claim. Creating a new namespace every time an existing namespace is heavily squatted will disrupt legitimate users of the existing namespace much more than it will disrupt squatters, even if a lot of the existing names are squatted. It also is an inherently cyclic process, since squatters can grab a new namespace just as fast as the old namespace. The correct way to disincentivise squatting (to the extent that it is a problem) is with changes to Namecoin’s fee structure.

A “More Structured” Spec

Another commonly cited “advantage” of u/ is that its JSON structure is allegedly better organized than that of id/. This is not an adequate reason to start a new namespace. Even if the u/ team didn’t want to directly work with us, they could have simply used their incompatible spec with the id/ namespace, and everything would have worked just fine. End users who wanted to use both specs would have been subject to the slight annoyance of having to enter duplicate fields in their existing names, but this would be infinitely better than needing a new name.


Several people have commented that because Namecoin is decentralized, or because it’s a general-purpose naming system, that it’s completely acceptable to create new namespaces without regard for the consequences. There is a fundamental difference between centralization and interoperability. Centralization would mean that an authority is dictating which names can and cannot be created; this would be extremely bad for end users. Interoperability means that the developer community is voluntarily standardizing on practices that allow everything to work together with minimal disruption; this directly benefits end users. We are for interoperability, not centralization. The ability to create new namespaces is primarily available for creating new applications. Of course, the blockchain validation math doesn’t care if two namespaces are used for similar things. This doesn’t mean it’s a good idea, or that people should be doing it on a regular basis.

Where From Here?

The u/ team has gotten themselves into a potentially bad situation, since now if they wish to move to id/, they’ll have to race against squatters: precisely the reason why we don’t recommend changing namespaces in the first place. We have limited sympathy for this predicament, since this could have easily been averted had they not created u/ in the first place. This has resulted in unnecessary trouble for end users, and we hope that a good resolution can be found.

Fix for OpenSSL Consensus Vulnerability has been deployed on 100% of mining hashpower

Fix for OpenSSL Consensus Vulnerability has been deployed on 100% of mining hashpower. Users of NamecoinQ (i.e. namecoind/Namecoin-Qt 0.3.x) are on semi-SPV security, and should wait for at least 6 confirmations for incoming transactions. Users of Namecoin Core (in beta) are on full-node security. Thanks to the miners for their quick action and everyone else who assisted in the response.

OpenSSL Consensus Vulnerability affects Namecoin

Namecoin Bounty Cornucopia

Namecoin’s 4th Birthday

The Namecoin blockchain is now four years old. Happy birthday!

N-O-D-E Interviews Daniel Kraft

Interview with Namecoin lead developer Daniel Kraft.

Name-Only Clients

Currently, the only options for people wanting to resolve Namecoin names are to deploy a full node or to trust results provided by someone else. It doesn’t have to be this way, though. Like with Bitcoin lightweight SPV clients which have much smaller local storage requirements can be created for Namecoin. Unlike Bitcoin, we can have “Namecoin Name-Only Clients” that give up support for “Namecoin as a currency” in exchange for better security and even lighter storage requirements.

Without the need to support currency transactions, a Namecoin SPV client can delete block headers that are more than 36,000 blocks old because they are not required to validate “current” (unexpired) name transactions. This data can be stored in a few dozen megabytes. We call this mode “SPV-Current” (SPV-C).

To support SPV-C, a name-only client must be able to query full nodes for transactions by name. This capability can either be added to the Namecoin “wire protocol” or operate as a separate service. Responses include cryptographic proof (using a Merkle hash tree) that the transaction was included in a block which the SPV-C client has headers for.

This basic implementation of SPV-C is vulnerable to a malicious node responding with an older (but non-expired) name transaction in response to a query or censoring the result. The easiest way to combat this is to query multiple full nodes and use the most recent response, but this is fragile. A more robust option would be to use a cryptographic (Merkle) hash tree to represent the list of all “unspent” transactions. This can be used to prove that it is responding with the latest data, since updating a name is done by “spending” the previous update.

The SPV-C client only needs to have the “root” of the hash tree (which is only 32 bytes long) to verify this proof. By having miners include this root hash in the coinbase transaction of every block, the set of all current names is verified continuously throughout the mining process. Since name operations are marked spent when they expire, the fact of a name transaction is unspent is proof that it is current. We call this Unspent Transaction Output Tree/Coinbase Commitments (UTXO-CBC).

Once the UTXO-CBC is included in all blocks, name-only clients can then keep track of the current root hash (more accurately, the root hash of the 12th deepest block, as keeping the UTXO set’s current at all blocks in memory is infeasible). When a client queries for a transaction by name, a full node will respond with the name transaction, proof that the transaction was included in a particular block, and that the name data hasn’t been updated by “spending” the transaction. UTXO-CBC constitutes a significant security improvement for SPV-C clients, as it prevents full nodes from returning anything but current name data. This mode is referred to as ‘SPV-C+UTXO-CBC’.

Implementing UTXO-CBC is complicated by a number of problems relating to the formulation of the cryptographic data structure representing the UTXO set. The most fundamental of these issues is that since new transactions occur continuously, it is important that miners be able to efficiently compute updates to the UTXO set. In other words, it must not be necessary for the entire cryptographic data structure to be recomputed when a new transaction is added to the set. Of course, any solution must preserve the ability to concisely represent the set and the ability to generate small, efficient proofs of inclusion. Thankfully, a similar UTXO coinbase attestation proposal has been made for Bitcoin, so existing work (such as the Authenticated Prefix Trees proposal) will be transferable to Namecoin.

The final security issue is ensuring that full nodes cannot censor names by simply lying “that name does not exist”. A very similar problem was solved in DNSSEC to provide “authenticated denial of existence” using a sorted list of all names. It’s possible to do this with the same sort of hash tree used to represent all unspent transactions. This commitment is referred to as Unspent Name Output Non-Existence CBC (UNO NX CBC). The UNO set is a name-only subset of the UTXO set.

Name-only clients can be improved incrementally, as attacks on even the basic SPV-C design require an attacker to control 100% of the full nodes connected to the target and even then it cannot arbitrarily forge data. Bootstrapping nodes can also attempt to provide a diverse selection of full nodes to clients, increasing the attack cost. However, UTXO CBC and UNO NX CBC reduce the amount of network traffic, reduce latency, and increase security, so they should be implemented eventually.

Hopefully this post has illustrated how both secure and lightweight resolution of Namecoin is not only possible but practical. Once implemented, name-only clients will provide a much better option to those who cannot run a full node versus all other currently available options which either provide no real security and/or require complete trust of a third party.

This post was slightly edited from its original version upon import to Jekyll, to more accurately reflect consensus among the Namecoin development community.

Developer Meeting Saturday, Jan. 3

Lately we’ve had a few new people who are interested in joining development. This is, of course, awesome. Unfortunately, helping them get started has been kind of ad-hoc, because there’s not a great way to have a low-latency conversation with current developers to bounce ideas off of. None of the current developers are in IRC at predictable, consistent times, and some developers are rarely on IRC at all. Forums have too much latency and overhead for quick back-and-forth discussions. This is a non-ideal situation.

So, we’re going to do an experiment – there will be a public developer IRC meeting in #namecoin-dev on Freenode on Saturday, Jan. 3, 9AM Pacific / 11AM Central / 12PM Eastern / 5PM UK / 6PM CET. We’re going to try to have as many Namecoin developers present as possible.

Current developers will give updates on what they’ve been doing; interested new developers can use it as an opportunity to get involved in discussions, ask questions, etc.; and interested average users will get to see more of how the development process works (because transparency is good). This bears some similarity to how Tor handles things.

Remember, this is an experiment, so we’re not quite sure how it will go. If it goes well, this may become a regular occurrence.

So, if you’ve been thinking of getting involved, or if you’re just curious, now’s your chance – stop by the developer meeting on Jan. 3 and talk to us. See you there!

Early Christmas Present for Namecoin

Christmas has come early for Namecoin: Discus Fish (aka F2Pool) has donated 20,000 namecoins to fund a reimplementation based on mainline Bitcoin!

What’s more is that chief Namecoin scientist Daniel Kraft has been working so hard that the code is already usable! Indeed, Discus Fish has been using it in production for a few weeks. The code is still considered experimental but you can check it out on Daniel’s Github repo. As always, make encrypted backups before playing around.

TL;DR: Namecoin is back!

This post was slightly edited from its original version upon import to Jekyll, to more accurately reflect consensus among the Namecoin development community.

New Version 0.3.80, Softfork Upcoming

This release smooths the transition to a new Namecoin codebase rebased on the latest version of Bitcoin!


Starting at block height 212500 (around New Year’s Eve) miners will begin applying some checks for edge cases. There is a a small chance that miners running older versions will fork, so all pool operators and solo miners must update. Regular users should update too but the traditional precaution of waiting for six confirmations should be safe as well.

Be safe and make an encrypted backup of your wallet.dat file before updating. Thanks to everybody who helped make this happen!

Download v0.3.80 here, and see the release notes and full changelog.

Happy Halving Day!

As of block 210000 the Namecoin block reward halved to 25NMC. Happy halving day!

Cakes for Competitors

The proliferation of cryptocurrencies working on decentralized TLDs has spurred a narrative of competition with Namecoin. However, the distance between our communities is small, and the competition is friendly. The free software movement has shown us that multiple approaches strengthen the ecosystem. Competition is not the zero-sum game fundamentalist Chicago-school economists make it out to be.

This blog post is based on a forum thread from September 21st.

The title of this post is a reference to the Internet Explorer and Firefox tradition of sending celebratory cakes for major releases. While the two teams are competitors, this competition has pushed them to create better products. We believe the same is true of cryptocurrencies.

Namecoin developers are in this game to win it, but “winning” is the creation of decentralized, secure, and usable naming systems for the internet. Gaining acceptance with the IETF, building more secure registrars, lightweight clients, usable browser integration, and dynamic domain pricing are just a few challenges facing cryptocurrencies looking to add a decentralized TLD.

From proof-of-work to funding models and governance styles, Namecoin is very different from BitShares, Ethereum, or CounterParty. Sticking to our academic background allows us to build more robust security models and better defend ourselves from political and legal attacks. However, it also means we have to apply for public funding and struggle to build consensus. We believe that this diversity ultimately strengthens the community as a whole.

The bottom line is that we wouldn’t be working on Namecoin if the technology and solutions we are building were not reusable. BitShares has already benefited greatly from our work, borrowing our namespace specifications, adopting our protocols, and more. Building a usable censorship resistant web will require significant blood, sweat, and tears from lots of smart people. We are happy to do our part, and we are looking forward to the contributions that comes from competition and cooperation with the other cryptos.

This post was slightly edited from its original version upon import to Jekyll, to more accurately reflect consensus among the Namecoin development community.

Official Social Media Accounts

A large number of unofficial social media accounts have been making false claims about Namecoin. While we wish to encourage a healthy community and decentralization, we take user safety very seriously. Content posted through these accounts may pose a threat to average users, and the Namecoin development team has established official social media accounts in an attempt to help protect users.

The most serious issue, by far, has been claims about Namecoin being anonymous. We know that if a product is advertised as anonymous, it will be used in high-risk situations. If the product turns out to not actually be anonymous it can end up killing its users.

There are a large number of unofficial accounts [1] that have actively posted claims about anonymity to Facebook and Twitter groups related to WikiLeaks, Anonymous, Whistleblowing, Occupy, and Tor. The Namecoin client has not been audited (even a little bit) for security over Tor, and a recent proxy leak issue was fixed in Namecoin-Qt after these postings occurred. If someone living under an oppressive regime had tried to use our software in conjunction with Tor, that proxy leak could have gotten them arrested, tortured, or killed as a result.

Namecoin transactions, including domain name purchases, are not anonymous. Namecoin, being based on the Nakamoto blockchain used in Bitcoin, inherently leaks large amounts of information about its users’ identity. In one early example, researchers Reid and Harrigan were able to trace stolen Bitcoins to a bank account where the funds were deposited, despite the thief using sophisticated attempts to anonymize the funds. In a later example, researchers Meiklejohn et. al successfully identified the cluster of most WikiLeaks donations, even for donors who utilized single-use addresses. As the graph theory and data mining experts take over from the cryptography experts, and as the financial incentive for targeted advertising increases, these attacks will only get more effective.

We have asked the owner(s) of these accounts to stop posting false assertions about Namecoin on multiple occasions. They have consistently disregarded our requests, sometimes claiming that it’s “just marketing” and that we “are not very good marketers.” After two of our developers criticized this behavior on the forum, they were banned from one Facebook group for “trying to make trouble”.

This reckless “marketing trumps accuracy” attitude is dangerous for Namecoin’s users and harmful to Namecoin’s and our professional reputations. We recognize the importance of anonymity and are working towards a client specifically designed to be used with Tor as well as adopting methods from ZeroCash for anonymously purchasing records (such as ‘.bit’ domains and ‘id/’ identities) on Namecoin [2].

At Namecoin, we try hard to avoid unnecessary drama and focus on development. We really wish we could trust these unofficial accounts to represent us on social media platforms, but they have unapologetically put Namecoin users at risk. We would like to welcome everyone to migrate from the unofficial accounts to the official ones listed below. We will delegate posting rights to community members that demonstrate competency and a respect for user safety.

[Jeremy edit 2017 05 10: social media accounts are now listed in the footer of every page on]

Stay safe,

- The Namecoin Development Team

[1] We won’t be linking to these accounts, since we don’t want to boost their PageRank. However, they are unfortunately very easy to find on the various social networks.

[2] Ironically, the owner of the social media accounts has cited development discussions regarding these features as evidence that his claims of anonymity are correct.

Namecoin & Retail Usage

Well-meaning investors have been pushing for various currency-related use cases for Namecoin such as ATMs, acceptance at retailers, etc. The core development team sees these efforts as benign but generally do not expend time nor funds on them. Why would developers of a currency not place a priority on currency related use-cases?

The answer is that we place a priority on the specific use-cases that differentiate Namecoin from Bitcoin: DNS, ID, etc. Namecoin’s value comes from its utility as a naming system whereas Bitcoin’s value is primarily derived from its use as a currency. Competing with Bitcoin for dominance as a currency of exchange is suicide: Bitcoin has network effects that will overpower every other competitor in its market.

Furthermore, it is not clear that generic retail use of Namecoin is beneficial: most retailers immediately exchange crypto currencies into a reserve currency. Spending Namecoin at a retailer is only a step removed from exchanging Namecoin for fiat directly. Use as a reserve currency is Bitcoin’s problem, we have our own troubles to worry about.

The Great Aggregating Postmortem

In the past couple of weeks, Namecoin suffered outages. Someone (whom we’ve nicknamed “The Aggregator”) tried consolidating a large quantity of “loose change” into a single address. When done correctly, this is good because it reduces the amount of data lite clients [Jeremy edit 2017 05 10: this means UTXO-pruned clients] need to keep. Unfortunately, a combination of volume and an oversight in fee policies led to miners getting knocked offline.

Within 48/hours, we released a patch fixing the low fees which should have stopped the transactions, but miners were slow to uptake the patch. We then increased performance and miners have since finished processing the remaining transactions.

Our initial response was slow because our core developers were traveling. However, we are taking further steps to mitigate similar problems, improve our response times, and improve communications with miners.

Technical deep dive after the jump.

Deep Dive

An unknown party (The Aggregator) began consolidating a massive volume (50,000-100,000K) of unspent outputs into a single address. However, namecoind has extreme difficulty selecting outputs to spend in a wallet containing tens of thousands of unspent outputs. The Aggregator appears to have attempted to address this by writing a script which manually built transactions spending 50 or 100 of those unspent outputs to a new address (N8h1WYaCpnZrN72Mnassymhdrm7tT6q5yL).

The problem is that each of these transactions were 17-30 KB and rather than the standard transaction fee of 0.005NMC per KB (rounded up), a flat fee of 0.005NMC was used. Namecoin, like Bitcoin actually has two fee values, MIN_TX_FEE (used by miners) and MIN_RELAY_TX_FEE (used by all other full nodes). This enables MIN_TX_FEE to be lowered down to MIN_RELAY_TX_FEE without nodes who haven’t yet upgraded refusing to forward transactions with the new lower fee. On Bitcoin, the ratio between MIN_TX_FEE and MIN_RELAY_TX_FEE is 5:1, but due to an oversight it was 50:1 in Namecoin. The result was that The Aggregator’s transactions had a large enough fee to be forwarded throughout the network, but were considered “insufficient fee/free” transactions by miners. Since there is very limited space in blocks for such transactions, they just kept building up in the miners’ memory pools. The volume of transactions soon began causing the merge-mining software run by pools to time-out trying to get work.

We released an initial “band-aid” patch which simply upped the MIN_RELAY_TX_FEE to stop these particular problem transactions from being rebroadcast or accepted by pools. Phelix and Domob put together an RC branch which fixed the performance issues associated with The Aggregator’s transactions. The transactions have all been process but we have had positive feedback from miners and will be merging the RC branch with mainline shortly.

Additional techniques are being discussed to ensure Namecoin can better handle situations where there are too many transactions being broadcast to process them all. One is to temporarily drop lowest-priority transactions in the event of a flood, while granting higher priority to name transactions (NAME_NEW, NAME_FIRSTUPDATE, NAME_UPDATE) in order to ensure that time-sensitive operations are not delayed. Bitcoin developers have planned enhancements which will further mitigate the problem.

It was observed that at one point only one pool was functional. This pool mined many blocks in a row with no transactions. We have identified this pool and have been in contact with the operator. They modified their software some time ago to ignore all transactions to address some performance issues. We do not believe there was any malicious intent on their part, and they have committed to working with us to get to a point where they can include transactions in their blocks.


Downtime is very bad; it opens us up to attacks and messes things up for businesses which depend on Namecoin. Trying to guarantee some arbitrary level of uptime is a fool’s errand but we endeavour to outline what went wrong and what steps we are taking to prevent similar issues from occurring in the future.

Each step of our response was unacceptably slow: discovering a problem, diagnosing the problem, submitting patches, and coordinating with miners all took far longer than they needed to. Our response was primarily slowed by the fact that two of our lead developers (Ryan and Domob) were both away from home with limited or no availability. There were other issues as well, which are addressed in the following recommendations, but this single factor significantly slowed every step of the process. Had they been available, we would have had patches out within 24 hours of the initial problem.

Initial Error Detection

The initial response times lagged mainly because we were unable to diagnose the problem. Individual developers (Ryan in particular) have patched clients which aid in diagnosing abnormalities. Initial detection of the problem lagged as well, individual users and developers noted problems but this took some time to reverberate. Automated monitoring system that will alert us to abnormalities on the network would be useful as well.


  • Document and share patched clients
    • Ryan
    • Anon developer M?
  • Setup automated monitoring √
    • Block discovery times. √ has agreed to help.
    • Mining Pool ratios. √ + Ryan
  • Testnet-in-a-box. (Domob/Ryan need to publish)

Pushing Fixes

We went nearly 48 hours between having a bandaid patch and pushing out a statically compiled binary. This occurred for the following reasons:

  • Indolering didn’t know how to properly communicate and distribute the fix.
  • Limited communications with pool operators: it appears that the miners did not apply the initial bandaid patch which would have fixed network issues immediately.
  • Even after the correct course of action was identified, it took 3-4 hours to create an official fork, produce a statically compiled binary, and post to the blog. We have been focusing our efforts on automating the build process for Libcoin, it should not be a problem moving forward.


  • Codify process for creating an emergency branch and binary √
  • Setup new alerts mailing list and ask pool operators to join √
  • Gather contact info for major pool operators. √
  • Setup multi-user access to Twitter.
  • Streamline build processes.
    • Jeremy Rand’s progress on Libcoin:
      • Travis CI/automated builds √
      • Functional unit testing √
      • Miner-specific unit tests (Libcoin doesn’t yet support mining).

Readiness & Coordination

In first-aid, the first thing you do is order bystanders to contact emergency services, direct traffic, etc. More developers would obviously help, but, akin to first-aid, emergencies need someone ensuring that progress is being made. Without a proper first responder, you have a lot of bystanders simply standing around.


  • Fix developer mailing list. √
  • Create security mailing list. (in progress)
  • Appointing an official emergency coordinator to ensure things are moving.
    • Has contact information of developers (including phone numbers) and miners.
    • Alternate for when emergency contact is unavailable.
  • Improve volunteer onboarding. (planned for September)
    • Improve documentation.
    • Better labeling of repos (deprecate mainline, rebrand Libcoind, etc)
    • Public development roadmap.
    • Organize bounties/tickets on needed items.


Big thanks to Domob, Ryan, Phelix, Jeremy Rand, Indolering, our anonymous devs, mining pool operators, and others for their help

While Domob and Phelix coded the final fix, many people contributed to development. Phelix and Jeremy Rand were omnipresent during the entire response, from raising the initial warning to diagnosing the problem, proposing fixes, and testing. At one point, Jeremy Rand pulled 36 hours with no sleep. Ryan was especially generous with his time during a business trip, pulling all-nighters to help us diagnose the problem, develop fixes, and communicate with the mining pools.

Indolering worked hard to coordinate the response and communicate with miners. Our anonymous developers were a huge help, it’s a shame we can’t thank them publicly.

Luke-Jr, CloudHashing, BitMinter,, and MegaBigPower helped us test our patches and provided feedback on miner performance.

Namecoin Response to Recent No-IP Seizure

On June 30, 2014, customers of the No-IP dynamic DNS service suddenly experienced an outage. According to media reports, the outage was not caused by a technical issue or any kind of negligence by No-IP, but rather by a court order requested by Microsoft, supposedly to fight cybercrime. For background, see No-IP’s official statement.

First off – we only know what was reported by the media. However, we are very concerned that a US judge decided to shut down an immensely popular service provider due to a few abuses by a tiny minority of its users, particularly with no due process afforded to No-IP.

At Namecoin, we believe that decentralization is the best way to prevent malicious takedowns. The only way to be certain that your domain will not be collateral damage to this kind of abusive court action is to make sure that it is mathematically infeasible to take it down without your consent. Bad lawyers can’t change the laws of math.

Namecoin supports dynamic DNS via the .bit top-level domain and the DyName software by Namecoin developer Jeremy Rand. DyName has existed since October 2013, and both Jeremy and Namecoin developer Daniel Kraft have invested development effort to improve the security of this use case. Dynamic DNS was tricky to implement securely with Namecoin, because updates have to be done automatically on a machine with network access, and if the wallet (which must be unencrypted to be used automatically) is compromised, control of the name could permanently be transferred to the attacker. We circumvented this by using a Namecoin specification feature called the “import” field. Under this system, the keys necessary to transfer control of your domain, or to impersonate the server it points to, remain on an encrypted wallet. If the keys used to update your IP are stolen, the worst the attacker can do is make your website go down until you notice and change keys (your visitors will receive a TLS error upon visiting your website in the meantime). Our software for accessing .bit domains, NMControl (which is used by FreeSpeechMe), supports this feature.

Namecoin also supports simulated dynamic DNS via Tor and I2P services. If you configure a .onion or .b32.i2p domain using Tor or I2P, you can give this domain a human-memorable name using Namecoin. The Namecoin software FreeSpeechMe has supported this for HTTP websites since December 2013. While bandwidth and latency are worse than standard IPv4, this method does not require any port forwarding or IPv6 connectivity (DyName requires one of these).

The system is not yet perfect. DyName DNS updates take approximately 10 minutes to propagate the network, and up to 30 minutes after that to be refreshed in the NMControl cache. The Tor and I2P service support does not yet support HTTPS and non-HTTP connections. Due to build issues, we haven’t yet been able to release a FreeSpeechMe update which includes the latest NMControl with support for DyName domains. And the Namecoin-Qt GUI does not yet make it easy to set up DyName or Tor/I2P .bit domains.

We believe that all of the above shortcomings are fixable. However, Namecoin developers are working on this in their free time, and we don’t have a significant financial stake in Namecoin like most altcoin developers do. If you’d like to support decentralized dynamic DNS to help prevent the next takedown, please consider contributing to a bounty for the features you want more attention paid to. And if you’re a developer and you want to help, get in touch with us on the forum.

New Website

Thanks to Shobute for designing and Indolering for pushing the new website.