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Re: [openpgp] Fingerprints and their collisions resistance

2013-01-04 13:56:53
On 01/04/2013 02:53 AM, Christian Aistleitner wrote:
Hi Andrey,

On Thu, Jan 03, 2013 at 03:30:14PM -0800, Andrey Jivsov wrote:
Instead of 80 bit is security (birthday
bounds) SHA-1 is listed as 51 bits on
http://en.wikipedia.org/wiki/Message_digest.

Since you mention the 51 bits part again and again ...

Do you have any data / research underpinning this 51 (Besides
Wikipedia)?

After all, the cited Wikipedia page links to the retracted variant of
an article :-(

Otherwise, the best /theoretical/ result that I know of is just
above 60.

It looks like this is from the paper "Classification and Generation of Disturbance Vectors for Collision Attacks against SHA-1"
published in 2011 in Designs, Codes and Cryptography
http://link.springer.com/article/10.1007%2Fs10623-010-9458-9?LI=true
with 27 citations in Google scholar. There you can find a dozen of different copies (or minor revisions?) of the paper and Wikipedia links one of them.

Should we rather say that the _practical_ value is about 60 (it's not to say that 2^60 is that practical, but that there is an expensive but an actionable attack plan). The following post leads the reader to the algorithm : http://www.schneier.com/blog/archives/2012/10/when_will_we_se.html
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