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diff --git a/_posts/2013-10-25-namecoind-ssl.md b/_posts/2013-10-25-namecoind-ssl.md deleted file mode 100644 index 2711a92..0000000 --- a/_posts/2013-10-25-namecoind-ssl.md +++ /dev/null @@ -1,248 +0,0 @@ ---- -title: Namecoin, A Replacement For SSL -description: >- - If we use the namecoin chain as a DNS service we get security almost for - free, along with lots of other benefits. ---- - -At [cryptic.io][cryptic] we are creating a client-side, in-browser encryption -system where a user can upload their already encrypted content to our storage -system and be 100% confident that their data can never be decrypted by anyone -but them. - -One of the main problems with this approach is that the client has to be sure -that the code that's being run in their browser is the correct code; that is, -that they aren't the subject of a man-in-the-middle attack where an attacker is -turning our strong encryption into weak encryption that they could later break. - -A component of our current solution is to deliver the site's javascript (and all -other assets, for that matter) using SSL encryption. This protects the files -from tampering in-between leaving our servers and being received by the client. -Unfortunately, SSL isn't 100% foolproof. This post aims to show why SSL is -faulty, and propose a solution. - -## SSL - -SSL is the mechanism by which web-browsers establish an encrypted connection to -web-servers. The goal of this connection is that only the destination -web-browser and the server know what data is passing between them. Anyone spying -on the connection would only see gibberish. To do this a secret key is first -established between the client and the server, and used to encrypt/decrypt all -data. As long as no-one but those parties knows that key, that data will never -be decrypted by anyone else. - -SSL is what's used to establish that secret key on a per-session basis, so that -a key isn't ever re-used and so only the client and the server know it. - -### Public-Private Key Cryptography - -SSL is based around public-private key cryptography. In a public-private key -system, you have both a public key which is generated from a private key. The -public key can be given to anyone, but the private key must remain hidden. There -are two main uses for these two keys: - -* Someone can encrypt a message with your public key, and only you (with the - private key) can decrypt it. - -* You can sign a message with your private key, and anyone with your public key - can verify that it was you and not someone else who signed it. - -These are both extremely useful functions, not just for internet traffic but for -any kind of communication form. Unfortunately, there remains a fundamental flaw. -At some point you must give your public key to the other person in an insecure -way. If an attacker was to intercept your message containing your public key and -swap it for their own, then all future communications could be compromised. That -attacker could create messages the other person would think are from you, and -the other person would encrypt messages meant for you but which would be -decrypt-able by the attacker. - -### How does SSL work? - -SSL is at its heart a public-private key system, but its aim is to be more -secure against the attack described above. - -SSL uses a trust-chain to verify that a public key is the intended one. Your web -browser has a built-in set of public keys, called the root certificates, that it -implicitly trusts. These root certificates are managed by a small number of -companies designated by some agency who decides on these things. - -When you receive a server's SSL certificate (its public key) that certificate -will be signed by a root certificate. You can verify that signature since you -have the root certificate's public key built into your browser. If the signature -checks out then you know a certificate authority trusts the public key the site -gave you, which means you can trust it too. - -There's a bit (a lot!) more to SSL than this, but this is enough to understand -the fundamental problems with it. - -### How SSL doesn't work - -SSL has a few glaring problems. One, it implies we trust the companies holding -the root certificates to not be compromised. If some malicious agency was to get -ahold of a root certificate they could listen in on any connection on the -internet by swapping a site's real certificate with one they generate on the -fly. They could trivially steal any data we send on the internet. - -The second problem is that it's expensive. Really expensive. If you're running a -business you'll have to shell out about $200 a year to keep your SSL certificate -signed (those signatures have an expiration date attached). Since there's very -few root authorities there's an effective monopoly on signatures, and there's -nothing we can do about it. For 200 bucks I know most people simply say "no -thanks" and go unencrypted. The solution is creating a bigger problem. - -## Bitcoins - -Time to switch gears, and propose a solution to the above issues: namecoins. I'm -going to first talk about what namecoins are, how they work, and why we need -them. To start with, namecoins are based on bitcoins. - -If you haven't yet checked out bitcoins, [I highly encourage you to do -so][bitcoins]. They're awesome, and I think they have a chance of really -changing the way we think of and use money in the future. At the moment they're -still a bit of a novelty in the tech realm, but they're growing in popularity. - -The rest of this post assumes you know more or less what bitcoins are, and how -they work. - -## Namecoins - -Few people actually know about bitcoins. Even fewer know that there's other -crypto-currencies besides bitcoins. Basically, developers of these alternative -currencies (altcoins, in the parlance of our times) took the original bitcoin -source code and modified it to produce a new, separate blockchain from the -original bitcoin one. The altcoins are based on the same idea as bitcoins -(namely, a chain of blocks representing all the transactions ever made), but -have slightly different characterstics. - -One of these altcoins is called namecoin. Where other altcoins aim to be digital -currencies, and used as such (like bitcoins), namecoin has a different goal. The -point of namecoin is to create a global, distributed, secure key-value store. -You spend namecoins to claim arbitrary keys (once you've claimed it, you own it -for a set period of time) and to give those keys arbitrary values. Anyone else -with namecoind running can see these values. - -### Why use it? - -A blockchain based on a digital currency seems like a weird idea at first. I -know when I first read about it I was less than thrilled. How is this better -than a DHT? It's a key-value store, why is there a currency involved? - -#### DHT - -DHT stands for Distributed Hash-Table. I'm not going to go too into how they -work, but suffice it to say that they are essentially a distributed key-value -store. Like namecoin. The difference is in the operation. DHTs operate by -spreading and replicating keys and their values across nodes in a P2P mesh. They -have [lots of issues][dht] as far as security goes, the main one being that it's -fairly easy for an attacker to forge the value for a given key, and very -difficult to stop them from doing so or even to detect that it's happened. - -Namecoins don't have this problem. To forge a particular key an attacker would -essentially have to create a new blockchain from a certain point in the existing -chain, and then replicate all the work put into the existing chain into that new -compromised one so that the new one is longer and other clients in the network -will except it. This is extremely non-trivial. - -#### Why a currency? - -To answer why a currency needs to be involved, we need to first look at how -bitcoin/namecoin work. When you take an action (send someone money, set a value -to a key) that action gets broadcast to the network. Nodes on the network -collect these actions into a block, which is just a collection of multiple -actions. Their goal is to find a hash of this new block, combined with some data -from the top-most block in the existing chain, combined with some arbitrary -data, such that the first n characters in the resulting hash are zeros (with n -constantly increasing). When they find one they broadcast it out on the network. -Assuming the block is legitimate they receive some number of coins as -compensation. - -That compensation is what keeps a blockchain based currency going. If there -were no compensation there would be no reason to mine except out of goodwill, so -far fewer people would do it. Since the chain can be compromised if a malicious -group has more computing power than all legitimate miners combined, having few -legitimate miners is a serious problem. - -In the case of namecoins, there's even more reason to involve a currency. Since -you have to spend money to make changes to the chain there's a disincentive for -attackers (read: idiots) to spam the chain with frivolous changes to keys. - -#### Why a *new* currency? - -I'll admit, it's a bit annoying to see all these altcoins popping up. I'm sure -many of them have some solid ideas backing them, but it also makes things -confusing for newcomers and dilutes the "market" of cryptocoin users; the more -users a particular chain has, the stronger it is. If we have many chains, all we -have are a bunch of weak chains. - -The exception to this gripe, for me, is namecoin. When I was first thinking -about this problem my instinct was to just use the existing bitcoin blockchain -as a key-value storage. However, the maintainers of the bitcoin clients -(who are, in effect, the maintainers of the chain) don't want the bitcoin -blockchain polluted with non-commerce related data. At first I disagreed; it's a -P2P network, no-one gets to say what I can or can't use the chain for! And -that's true. But things work out better for everyone involved if there's two -chains. - -Bitcoin is a currency. Namecoin is a key-value store (with a currency as its -driving force). Those are two completely different use-cases, with two -completely difference usage characteristics. And we don't know yet what those -characteristics are, or if they'll change. If the chain-maintainers have to deal -with a mingled chain we could very well be tying their hands with regards to -what they can or can't change with regards to the behavior of the chain, since -improving performance for one use-case may hurt the performance of the other. -With two separate chains the maintainers of each are free to do what they see -fit to keep their respective chains operating as smoothly as possible. -Additionally, if for some reason bitcoins fall by the wayside, namecoin will -still have a shot at continuing operation since it isn't tied to the former. -Tldr: separation of concerns. - -## Namecoin as an alternative to SSL - -And now to tie it all together. - -There are already a number of proposed formats for standardizing how we store -data on the namecoin chain so that we can start building tools around it. I'm -not hugely concerned with the particulars of those standards, only that we can, -in some way, standardize on attaching a public key (or a fingerprint of one) to -some key on the namecoin blockchain. When you visit a website, the server -would then send both its public key and the namecoin chain key to be checked -against to the browser, and the browser would validate that the public key it -received is the same as the one on the namecoin chain. - -The main issue with this is that it requires another round-trip when visiting a -website: One for DNS, and one to check the namecoin chain. And where would this -chain even be hosted? - -My proposition is there would exist a number of publicly available servers -hosting a namecoind process that anyone in the world could send requests for -values on the chain. Browsers could then be made with a couple of these -hardwired in. ISPs could also run their own copies at various points in their -network to improve response-rates and decrease load on the globally public -servers. Furthermore, the paranoid could host their own and be absolutely sure -that the data they're receiving is valid. - -If the above scheme sounds a lot like what we currently use for DNS, that's -because it is. In fact, one of namecoin's major goals is that it be used as a -replacement for DNS, and most of the talk around it is focused on this subject. -DNS has many of the same problems as SSL, namely single-point-of-failure and -that it's run by a centralized agency that we have to pay arbitrarily high fees -to. By switching our DNS and SSL infrastructure to use namecoin we could kill -two horribly annoying, monopolized, expensive birds with a single stone. - -That's it. If we use the namecoin chain as a DNS service we get security almost -for free, along with lots of other benefits. To make this happen we need -cooperation from browser makers, and to standardize on a simple way of -retrieving DNS information from the chain that the browsers can use. The -protocol doesn't need to be very complex, I think HTTP/REST should suffice, -since the meat of the data will be embedded in the JSON value on the namecoin -chain. - -If you want to contribute or learn more please check out [namecoin][nmc] and -specifically the [d namespace proposal][dns] for it. - -[cryptic]: http://cryptic.io -[bitcoins]: http://vimeo.com/63502573 -[dht]: http://www.globule.org/publi/SDST_acmcs2009.pdf -[nsa]: https://www.schneier.com/blog/archives/2013/09/new_nsa_leak_sh.html -[nmc]: http://dot-bit.org/Main_Page -[dns]: http://dot-bit.org/Namespace:Domain_names_v2.0 |