Re: Silicon.fr reporting GSM crypto broken

[[EMAIL PROTECTED] (David Wagner)]

Owen Blacker  wrote:
>Though I think their paragraph "The security loophole arises because of
>a fundamental mistake made by GSM developers in creating a system which
>corrected for interference of the line prior to encrypting a
>conversation, he explained." might be down to poor translation
>somewhere (from Hebrew, maybe?) as my translation feels like it makes
>more sense to me.

GSM compresses before encrypting.  This means that some of the input to
the encryption is known.  This in turn makes ciphertext-only attacks
on GSM possible.  Then they exploited a number of protocol attacks to
show how to use attacks on A5/2 (the weak cipher) to recover A5/1 keys,
even without cryptanalyzing A5/1 itself.  An impressive piece of work.
If you missed the talk at CRYPTO, you really missed out!