SecurityRatty: Cryptanalysis of A5/1

This is cache of http://www.schneier.com/blog/archives/2008/02/cryptanalysis_o_1.html. Cache is the snapshot of article that we took when we index feed.
To see original page click here.
We are not affiliated with the authors of this article and not responsible for its content.

Cryptanalysis of A5/1

2008-02-22 06:31:45 by schneier in Schneier on Security

There have been a lot of articles about the new attack against the GSM cell phone encryption algorithm, A5/1. In some ways, this isn't real news; we've seen A5/1 cryptanalysis papers as far back as ten years ago.

What's new about this attack is: 1) it's completely passive, 2) its total hardware cost is around $1,000, and 3) the total time to break the key is about 30 minutes. That's impressive.

The cryptanalysis of A5/1 demonstrates an important cryptographic maxim: attacks always get better; they never get worse. This is why we tend to abandon algorithms at the first sign of weakness; we know that with time, the weaknesses will be exploited more effectively to yield better and faster attacks.