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Re: [openpgp] Fingerprints and their collisions resistance

2013-01-04 15:00:50
On Fri, 04 Jan 2013 11:56:36 -0800
Andrey Jivsov <openpgp(_at_)brainhub(_dot_)org> wrote:

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

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

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

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
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 :

In either case, humans are less than 2^33 todays and this number should not 
increase so much in the next decades. Even if each living human use OpenPGP and 
more than a dozen of keys, we are far from 2^60 or 2^51...

(even if we consider also the life expectancy)

jbar <jeanjacquesbrucker(_at_)gmail(_dot_)com>

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