Talk: Common crypto mistakes in Android

Date Tuesday, December 16, 2014 Time 11:00 AM
Speaker Isaac Potoczny-Jones


If you do a web search for “encrypting Strings in Android”, you’ll find a lot of example code, and they all look pretty similar. They definitely input a String and output gibberish that looks like encrypted text, but they are often incorrect. Crypto is tricky: it’s hard to tell that the gibberish that’s being printed is not good crypto, and it’s hard to tell that the code example you picked up from Stack Overflow has serious flaws.

The problem here is that sites like Google and Stack Overflow rank results based on popularity, but the correctness of crypto isn’t something we can vote about. It’s not a popularity contest. To use it correctly, you have to understand the properties of the algorithm and the security goals of your code. Maybe the bad crypto someone pasted up on the Internet was acceptable for their needs, but there’s a good chance it’s completely unacceptable for yours.

In this talk, we’ll discuss the use of a very common crypto algorithm, AES, and show how code examples on the Internet usually make serious mistakes in how they use AES libraries. What are the consequences of these mistakes and what are more reasonable defaults. We’ll also talk a bit about our simple Android library that tries to do AES right.

More information on the Tozny blog.