[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: Generating 3DES keys from SKEYID_e
>>> The attacker then runs every one of those 2^128 SKEYID_e through the
>>> algorithm above (requiring 3*2^128 md5 computations), and ends up with
>>> 2^128 possible 3des keys.
>> Stephane,
>>
>> do you realize how large 2^128 is?
>It's higher than I can count, I know that. :)
2^128 = 2^32 * 2^32 * 2^32 * 2^32
where 2^32 = (roughly) 4 billion
Assume an ASIC implements twelve MD5 circuits, and each of these circuits
runs at 1 GHz in pipelined mode and completes one MD5 result per
nanosecond, it just takes a second to run through 2^32 combinations.
2^96 to go.
Assume you run this computation for 136 years, this takes care of another
2^32.
2^64 to go.
Assume you distribute one of these ASICs to every man, woman and child
(let's exclude toddlers) on this planet, this takes care of another 2^32.
2^32 to go.
Assume our galaxy has 2^32 planets that have intelligent life on them,
and assume each of these planets has a few billion intelligent beings on
it on the average, then, yes, an entire galaxy working together can conduct
an exhaustive search in 136 earth years.
Greg Glawitsch
Network Associates, Inc.