Irreal

I have written several times about the absolute necessity to properly hash passwords. The tricky part is that properly. It’s a bit subtle to get it right. Happily the folks over at Defuse Security have an excellent guide that

• Tells you what to do
• Tells you what not to do
• Provides source code to proper implementations in PHP, Java, C#, and Ruby

If you’re a developer tasked with the customer authentication system, be sure to read this. There’s lots of good advice in it. And whatever you do, don’t store the passwords in plain text. If you do, you’re going to end up here and be the object of universal derision and scorn.

One of the recently released Snowden documents mentions the NSA’s success at weakening a 2006 NIST encryption standard and getting it accepted as an international ISO standard. While the standard isn’t named, it is widely assumed to be NIST Special Publication 800-90A with the Dual_ECDRBG random number generator being the weakened algorithm. Indeed, the algorithm was weakened to such an extent that it can be said to have a backdoor.

Matthew Green, a John Hopkins research professor, has a great post on Dual_ECDRBG and its flaws. He explains what the flaw is and how it is exploited. The article is fairly technical but not overly mathematical so interested Irreal readers should be able to follow it without problems.

Ironically, Dual_ECDRBG is very slow (about 3 orders of magnitude slower than the other RNGs in SP 800-90A) so there is no reason to use it except these types of algorithms can be proved to be secure and the cautious implementer may be willing to sacrifice the performance for the security. Unfortunately, NIST neglected to include such a proof in SP 800-90A and when cryptographers took a close look they discovered many problems with the algorithm. Read Green’s post for the details.

Incredibly, despite these problems having been known since 2007, there are still implementations using the algorithm. Meanwhile, NIST has reopened public comment on SP 800-90A and is strongly recommending that Dual_ECDRBG not be used until the standard is reissued.

If the NSA scandals are making you paranoid—and they should—one of the first steps you should take is to install email encryption software. Every time you read an article recommending the use of encryption software, the author inevitably remarks that it’s “hard” or “tricky” to set up GPG or PGP. That isn’t true. Really. Even your Mom can do. In the case of OS X, you just download GPG Tools and install it in the usual way. Other operating systems have similar packages.

If you’re extra paranoid and have a C compiler available, you can download GnuPG and compile it yourself. Of course, unless you’re a cryptography expert, in which case you already know all this, you’re still trusting GnuPG’s authors to implement the crypto correctly and not insert any weaknesses or backdoors. Since GnuPG is open source and lots of people who are crypto experts are looking at the source code, this seems an acceptable risk. As a practical matter, what better choices do you have?

That brings us to generating the keys that you use for encryption and signing. GnuPG walks you through that process and you don’t have to understand any of the technical details; just follow the prompts and choose the defaults. If you want to generate the strongest possible keys, Alex Cabal has an excellent post on Creating the Perfect GPG Keypair. Cabal walks you through the key generation process and tells you what choice you should make at each step to ensure a strong keypair.

Cabal also explains how to limit the inconvenience of a lost or compromised key. This is mostly for laptop users who may have their computer lost or stolen. On the other hand, your keys should be protected by a strong password so you may or may not want to take this additional step.

If you’ve been thinking about setting up email encryption or want to strengthen your current keys and encryption as much as possible, head on over and read Cabal’s post. It’s a good resource and shows you what to do even if you don’t understand the technical details of the crypto.