Tuesday, January 12, 2010

KASUMI (A5/3), 3G GSM Wireless Cipher Hacked

3G GSM Wireless Cipher KASUMI Hacked snapvoip.blogspot.com
The standard cipher  used on 3G GSM networks known to us as KASUMI has been broken by a team of cryptographers.
Even though the paper is not public yet, but the Emergent Chaos blog carries an article on the attack. It also published a portion of the abstract of the paper;

In this paper we describe a new type of attack called a sandwich attack, and use it to construct a simple distinguisher for 7 of the 8 rounds of KASUMI with an amazingly high probability of 2−14. By using this distinguisher and analyzing the single remaining round, we can derive the complete 128 bit key of the full KASUMI by using only 4 related keys, 226 data, 230 bytes of memory, and 232 time. These complexities are so small that we have actually simulated the attack in less than two hours on a single PC, and experimentally verified its correctness and complexity. Interestingly, neither our technique nor any other published attack can break MISTY in less than the 2128 complexity of exhaustive search, which indicates that the changes made by the GSM Association in moving from MISTY to KASUMI resulted in a much weaker cryptosystem.
 Emergent Chaos blog via Threatpost


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