RSA's RC5-64 Secret Key Challenge has been solved.

[Ralf-P. Weinmann]

On Thu, Sep 26, 2002 at 02:45:12PM -0700, John Gilmore wrote:
> [...]
> 
> After getting that getting started, though, I suggest beginning a
> brute-force attack on the GSM cellphone encryption algorithm.  That's
> in use in hundreds of millions of devices worldwide, protecting (or
> failing to protect) the privacy of billions of phone calls a day.

Is A5/3 deployed yet? If not, a brute force attack is not needed, for A5/1 and
A5/2 more efficient tools exist to cryptanalyse it. Even in real-time, although
you might need to invest in some hard disk space before being able to eavesdrop
and intercept. See the following paper for more information:

"A. Biryukov, A. Shamir and D. Wagner, Real Time Cryptanalysis of A5/1 on a PC"

As for A5/3, I'm not really sure what key length network operators are/will be
using, 64-128 bits are allowed in the design requirements documentation. The
specification should be available on the 3GPP website. A5/3 is based on Kasumi.

Cheers,
Ralf

-- 
Ralf-P. Weinmann <rpw at uni.de>
PGP fingerprint: 2048/46C772078ACB58DEF6EBF8030CBF1724

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