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Re: Paranoid



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I'm not exactly sure what this thread is about :-) but I do have some
numbers:

Differential cryptanalysis of DES requires 2^47 = 140737488355328 =
1.4 10^14 known plaintexts.

The complexity of a brute force DES attack (keysearch) is 2^56 =
72057594037927936 = 7.2 10^16, or 2^55 = 36028797018963968 = 3.6 10^16
if you are efficient.

Similary, brute forcing IDEA is 2^128 =
340282366920938463463374607431768211456 = 3.4 10^38

The best factoring algorithm (gopher plug: check in Misc/ for
a recent "bits and difficulty factoring post") for a 1024 bit key is 
a complexity of 4.42 10^29.

Somewhere around 1600 bits comes a point where it is "easier" to
attack IDEA than factor the resulting number.

Karl Barrus
<[email protected]>

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