A5/2 is a
stream cipherused to provide voice privacy in the GSMcellular telephone protocol.
The cipher is based around a combination of four
linear feedback shift registers with irregular clocking and a non-linearcombiner.
1999, Ian Goldbergand David Wagnercryptanalyzed A5/2 in the same month it was published, and showed that it was extremely weak — so much so that low end equipment can probably break it in real time.
Since July 1, 2006, the GSMA (GSM Association) mandated that GSM Mobile Phones will not support the A5/2 Cipher any longer, due to its weakness, and the fact that A5/1 is deemed mandatory by the
* KASUMI, also known as A5/3
* [http://www.CryptoDox.com/A5/2 A5/2] at CryptoDox
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