Found this somewere.
Any coments?
/Per
16 December 1999
Joint statement by Chairman GSM Association Security Group and
Chairman ETSI SMG10 Security Group
Many questions were raised by the paper of Alex Biryukov and Adi
Shamir [1] on the GSM A5/1 over the air encryption algorithm, we would
like to make the following comments:
The paper describes an interesting application of the time^^memory
trade^^off principle to the A5/1 algorithm. This results in the
described attack on A5/1 requiring known plaintext relating to the
first few minutes of a GSM call.
We, and others, have previously examined similar attacks against A5/1,
but they were considered not practicable. This is because the nature
of the design of the GSM voice encoding and the GSM frame structure
leads to very little known plaintext for A5/1.
Although of theoretical interest, the attack described by Biryukov and
Shamir requires a similar quantity of known plaintext and must
therefore be considered to be mainly of academic interest. There is
still no evidence of any commercial violation of the A5/1 algorithm,
which has now been in use for more than ten years.
However, we are not complacent about GSM security and remain totally
committed to constantly enhancing the protection offered to our
customers and to ensuring that GSM is afforded even better security.
Michael Walker Chairman ETSI SMG 10
Charles Brockton Chairman GSMA SG
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Per Kangru, physics student at Uppsala University, part time worker at
Idonex AB. All opinons are mine and does not necessarily have any
influence over the opinons of Idonex AB or Uppsala University.
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