Re: [Full-disclosure] Chinese Professor Cracks Fifth Data Security Algorithm (SHA-1)



Dear Tim,

--Wednesday, March 21, 2007, 7:24:35 PM, you wrote to full-disclosure@xxxxxxxxxxxxxxxxx:


T> Secondly, 3APA3A, birthday attacks against the collision-resistance
T> property of a hash take approximately 2^(b/2) time, where b is the
T> number of bits. That is, brute-force birthday attacks would take around
T> 2^80 time against SHA-1. These attacks reduce the complexity to 2^63,
T> or thereabouts, at least from what I've read previously[1].

Yes, I was wrong. I thought "2000 times" applies to direct bruteforce,
not to birthday attack. In this case complexity estimations for birthday
attack may be ~2^74, an equivalent for birthday attack against 148 bit
hash.

T> As for US courts... which case are you referring to (as I'd be
T> interested to read the results)? The only one I know of involving MD5
T> was an Australian case[2].

And again yes, it was really Australian case.

T> cheers,
T> tim

T> 1. http://www.schneier.com/blog/archives/2005/08/new_cryptanalyt.html

T> 2. http://news.com.com/2061-10789_3-5829714.html


--
~/ZARAZA http://securityvulns.com/
Таким образом он умирает в шестой раз - и опять на новом месте. (Твен)

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