This morning, I gave a talk at TrueNorth PHP. The talk was aimed at explaining the basics of Cryptography as needed for the average developer. It is intended to give a high level understanding of cryptography and cryptographic techniques. So, with no further adue, here’s the slides:
Last week, I was at PHP North West. The conference was incredible to say the least. One of the best I’ve been to in a very long time. But to the point of this post, I did an unconference talk about password hashing in PHP. Since I had my camera with me, I also took video of it. So included in this post is both the slides from the talk, and the video of the talk. So, with no further adue:
Every day I come across code that is insecure. Sometimes the code is so hilariously insecure that any 10 year old could break it. I’ve also gotten into discussions with people who should know better about their practices. It’s very, how to put this, disheartening. It’s sad that the average developer knows (and cares) so little about proper security practices. So, I’ve put together a simple pledge (or manifesto, if you’d like).
Yesterday, I read an article about using GPUs to accelerate password hashing: No, Heavy Salting of Passwords Is Not Enough, Use CUDA Accelerated PBKDF2. The article makes some very interesting points about password hashing. But the conclusion of the article really misses a huge point, and get a major point fundamentally wrong (bordering on misunderstanding). Let’s start with the part they got wrong…
The other day I announced the release of my new password hashing library, PasswordLib. As I’ve come to expect, Reddit was full of interesting commentary on the topic. Some was good, some was bad and some surprised me. What surprised me was the insistence on a global salt (otherwise known as a “pepper”). So, I started thinking about it some more, and I figured I’d write a post on why I don’t use peppers in my hashing algorithms (and why you may want to rethink it too).
Today, I’m proud to announce the immediate availability of a new password hashing library for PHP: PasswordLib. The project is a spin-off of another that I started about a year ago, CryptLib. I was unable to find a clean solution to a few problems in CryptLib, so dev work stalled for a while. I realized recently that the password hashing functionality was complete, so if I stripped out the incomplete parts, it would still be a very useful library. And so PasswordLib was born.
Well ok, not really. But you should not be securing hashes against rainbow tables anymore, you need to secure them against brute forcing. Rainbow tables are still very effective for simple hashes (md5($password)), but just because an algorithm is hard to use for a rainbow table doesn’t mean that it is safe, because the rainbow table is dead…
The other day, an article popped up in my feed reader that had a very interesting title (to me at least), Simple and Secure Login Script. As usual, I decided to click the link and give the article a read. Not overly shocking was the fact that I didn’t find the content of the article to be, how shall I say this…, overly factual. It’s not really a “tutorial”, but more of a “here’s some code that’s secure”. A quick review of the code found more than one vulnerability, and some significant things that I would change about it (as well as a few “really bad practices”).
So, rather than write a “rant post” about the code, I’ve decided to take another tactic. In this article, I’m going to walk you through my process for performing a security code review. Inline with the review, we’ll take note of any issues that we do find, and number them. Then at the end of the review, we’ll go over each one and look at potential mediation that we can apply and how to fix the issues.
When we talk about “random” numbers, we generally talk about two fundamental properties: Predictability and Bias. Both are closely related, but are subtly different. Predictability in reference to random numbers is the statistical problem of predicting the next value when knowing any number of previous values. Bias on the other hand is the statistical problem of predicting the next value when knowing the distribution of previous values.
As promised, I’m going to post the slides from last night’s talk on XSS prevention with PHP here. There was a fair turnout, with a few following the live stream of the talk. I must thank those who came, as there was definitely some good interaction and questions.