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Archive for December, 2010

Cracking BlackBerry backups is now slower… but still possible, thx to GPU acceleration

Friday, December 24th, 2010

If you have read our recent Cracking BlackBerry Backup Passwords article, you should be familiar with encryption implemented in BlackBerry Desktop Software. Just reminding:

In short, standard key-derivation function, PBKDF2, is used in a very strange way, to say the least. Where Apple has used 2’000 iterations in iOS 3.x, and 10’000 iterations in iOS 4.x, BlackBerry uses only one.

So password verification is (was) so fast/simple that we did not care about implementing it on the GPU — modern CPU is able to crack almost 8 million passwords per second (thanks to multi-threading and AES-NI). We would not call that the vulnerability, but still the weak link.

But new versions of BlackBerry Desktop Software have been released reсently (6.0 for Windows and 2.0 for Mac). And as always, there are bad news and there are good news.

BlackBerry password cracking: multi-threaded, with hardware-accelerated AES

Thursday, December 9th, 2010

Most modern CPUs are multi-core – it is not easy to find even a laptop with less than two cores these days. And for desktops, 4 cores are usual now.

Password recovery is one of most CPU-intensive tasks, and it fits best into multi-processor architecture. Every CPU (or CPU core) get its own portion of passwords to try (i.e. to check their validness), and they all work in parallel. As simple as that.

So what we’re doing in our software is running multiple threads – as many as the number of CPUs (or cores) available. And the rest is being done by the operating system, that assigns the threads to cores (well, in most cases we don’t care what particular core is going to execute a particular thread, because they are all equal; the only exception is when one or more of the cores is doing something already, I mean something CPU-intensive as well).