Re: SHA1 hash safety

2005-04-20 Thread David Meybohm
On Tue, Apr 19, 2005 at 06:48:57PM -0400, C. Scott Ananian wrote: > On Tue, 19 Apr 2005, David Meybohm wrote: > > >But doesn't this require assuming the distribution of MD5 is uniform, > >and don't the papers finding collisions in less show it's not? So, your > >birthday-argument for calculating t

Re: SHA1 hash safety

2005-04-19 Thread C. Scott Ananian
On Tue, 19 Apr 2005, David Meybohm wrote: But doesn't this require assuming the distribution of MD5 is uniform, and don't the papers finding collisions in less show it's not? So, your birthday-argument for calculating the probability wouldn't apply, because it rests on the assumption MD5 is uniform

Re: SHA1 hash safety

2005-04-19 Thread David Meybohm
On Mon, Apr 18, 2005 at 12:43:23AM -0700, Andy Isaacson wrote: > > I'm not going to do the sums, but I would hazard a guess that it's more > likely your PC suffered a cosmic-ray-induced memory fault - EACH OF THE > FOUR TIMES YOU TESTED IT - causing it to report the same MD5, than that > you actua

Re: SHA1 hash safety

2005-04-18 Thread C. Scott Ananian
On Mon, 18 Apr 2005, Andy Isaacson wrote: If you had actual evidence of a collision, I'd love to see it - even if it's just the equivalent of % md5 foo d3b07384d113edec49eaa6238ad5ff00 foo % md5 bar d3b07384d113edec49eaa6238ad5ff00 bar % cmp foo bar foo bar differ: byte 25, line 1 % But in the abse

Re: SHA1 hash safety

2005-04-18 Thread C. Scott Ananian
On Sun, 17 Apr 2005, Horst von Brand wrote: crypto-babble about collision whitepapers is uninteresting without a repo that has real collisions. git is far too cool as is - prove I Just copy over a file (might be the first step in splitting it, or a header file that is duplicated for convenience, .

Re: SHA1 hash safety

2005-04-18 Thread Andy Isaacson
[trimmed cc list, nobody wants to read this noise] On Sat, Apr 16, 2005 at 11:35:39PM +0200, Brian O'Mahoney wrote: > >> (1) I _have_ seen real-life collisions with MD5, in the context of > >>Document management systems containing ~10^6 ms-WORD documents. > > > > Dude! You could have been *f

Re: SHA1 hash safety

2005-04-17 Thread Theodore Ts'o
On Sun, Apr 17, 2005 at 12:38:37AM -0400, David A. Wheeler wrote: > The probability of an accidental overlap for SHA-1 for two > different files is absurdly remote; it's just not worth worrying about. > > However, the possibility of an INTENTIONAL overlap is a completely > different matter. I thi

Re: SHA1 hash safety

2005-04-17 Thread Brian O'Mahoney
Linus wants to drive ahead, and ignore the collision issue for now, and has been dismissive of the risks, he wants a result not heart searching, and the list comments exhibit a confusion with the engineering problem of avoiding accidental collisions v deliberate sabotage. Since this is not a show-

Re: SHA1 hash safety

2005-04-17 Thread Horst von Brand
[EMAIL PROTECTED] said: [...] > Linus has already weighed in that he doesn't give a crap. All the > crypto-babble about collision whitepapers is uninteresting without a > repo that has real collisions. git is far too cool as is - prove I > should be concerned. Just copy over a file (might be t

Re: SHA1 hash safety

2005-04-16 Thread Paul Jackson
I have nothing further to contribute to this subtopic. Good luck with it. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <[EMAIL PROTECTED]> 1.650.933.1373, 1.925.600.0401 - To unsubscribe from this list: se

Re: SHA1 hash safety

2005-04-16 Thread Tkil
> "Tkil" == Tkil <[EMAIL PROTECTED]> writes: Tkil> but the chance of any collision at all wigs me out. > "Paul" == Paul Jackson <[EMAIL PROTECTED]> writes: Paul> Guess you're just going to get wigged out then. Wig wig. :) I didn't mean "wigs me out to the point I won't use it" but mo

Re: SHA1 hash safety

2005-04-16 Thread David A. Wheeler
Paul Jackson wrote: what I'm talking about is the chance that somewhere, sometime there will be two different documents that end up with the same hash I have vastly greater chance of a file colliding due to hardware or software glitch than a random message digest collision of two legitimate docume

Re: SHA1 hash safety

2005-04-16 Thread Paul Jackson
> but the chance of any collision at all wigs me out. Guess you're just going to get wigged out then. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <[EMAIL PROTECTED]> 1.650.933.1373, 1.925.600.0401 - To u

Re: SHA1 hash safety

2005-04-16 Thread Tkil
> "Brian" == Brian O'Mahoney <[EMAIL PROTECTED]> writes: Brian> (1) I _have_ seen real-life collisions with MD5, in the context Brian> of Document management systems containing ~10^6 ms-WORD Brian> documents. Was this whole-document based, or was it blocked or otherwise chunked? I'm

Re: SHA1 hash safety

2005-04-16 Thread Martin Mares
Hi! > We've already computed the chances of a random pure hash collision > with SHA1 - it's something like an average of 1 collision every > 10 billion years if we have 10,000 coders generating 1 new file > version every minute, non-stop, 24 hours a day, 365 days a year. GIT is safe even for the

Re: SHA1 hash safety

2005-04-16 Thread Paul Jackson
> sysadmins realize that there are an infinante number of files that map to Sysadmins know that there are an infinite ways for their systems to crap out, and try to cover for the ones that there is a snow balls chance in Hades of them seeing in their lifetime. -- I won't rest

Re: SHA1 hash safety

2005-04-16 Thread Paul Jackson
> what I'm talking about is the chance that somewhere, sometime there will > be two different documents that end up with the same hash I have vastly greater chance of a file colliding due to hardware or software glitch than a random message digest collision of two legitimate documents. I've lost

Re: Re: SHA1 hash safety

2005-04-16 Thread David Lang
rnel.org Subject: Re: Re: SHA1 hash safety On Sat, 16 Apr 2005, Petr Baudis wrote: I know the current state of the art here. It's going to take more than just hearsay to convince me that full 128-bit MD5 collisions are likely. http://cryptography.hyperlink.cz/MD5_collisions.html OK, OK, I spoke t

Re: SHA1 hash safety

2005-04-16 Thread David Lang
te: Sat, 16 Apr 2005 10:58:15 -0400 (EDT) From: C. Scott Ananian <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] Cc: David Lang <[EMAIL PROTECTED]>, Ingo Molnar <[EMAIL PROTECTED]>, git@vger.kernel.org Subject: Re: SHA1 hash safety On Sat, 16 Apr 2005, Brian O'Mahoney wrote: (1) I

Re: SHA1 hash safety

2005-04-16 Thread David Lang
On Sat, 16 Apr 2005, Brian O'Mahoney wrote: Three points: (1) I _have_ seen real-life collisions with MD5, in the context of Document management systems containing ~10^6 ms-WORD documents. (2) The HMAC (ethernet-harware-address) of any interface _should_ help to make a unique Id. you want a u

Re: SHA1 hash safety

2005-04-16 Thread Brian O'Mahoney
Please see below: C. Scott Ananian wrote: > On Sat, 16 Apr 2005, Brian O'Mahoney wrote: > >> (1) I _have_ seen real-life collisions with MD5, in the context of >>Document management systems containing ~10^6 ms-WORD documents. > > > Dude! You could have been *famous*! Why the > aitch-ee-do

Re: SHA1 hash safety

2005-04-16 Thread Paul Jackson
Scott wrote: > Please, let's talk about hash collisions responsibly. Agreed. Chasing down links from the one Petr provided: http://cryptography.hyperlink.cz/MD5_collisions.html the best read I found was: MD5 To Be Considered Harmful Someday http://eprint.iacr.org/2004/357.pdf As the aut

Re: SHA1 hash safety

2005-04-16 Thread ross
On Sat, Apr 16, 2005 at 10:58:15AM -0400, C. Scott Ananian wrote: > Even given the known weaknesses in MD5, it would take much more than a > million documents to find MD5 collisions. I can only conclude that the > hash was being used incorrectly; most likely truncated (my wild-ass guess > would

Re: Re: SHA1 hash safety

2005-04-16 Thread C. Scott Ananian
On Sat, 16 Apr 2005, Petr Baudis wrote: I know the current state of the art here. It's going to take more than just hearsay to convince me that full 128-bit MD5 collisions are likely. http://cryptography.hyperlink.cz/MD5_collisions.html OK, OK, I spoke too sloppily. Let me rephrase: It's going

Re: Re: SHA1 hash safety

2005-04-16 Thread Petr Baudis
Dear diary, on Sat, Apr 16, 2005 at 04:58:15PM CEST, I got a letter where "C. Scott Ananian" <[EMAIL PROTECTED]> told me that... > On Sat, 16 Apr 2005, Brian O'Mahoney wrote: > > >(1) I _have_ seen real-life collisions with MD5, in the context of > > Document management systems containing ~10^6

Re: SHA1 hash safety

2005-04-16 Thread C. Scott Ananian
On Sat, 16 Apr 2005, Brian O'Mahoney wrote: (1) I _have_ seen real-life collisions with MD5, in the context of Document management systems containing ~10^6 ms-WORD documents. Dude! You could have been *famous*! Why the aitch-ee-double-hockey-sticks didn't you publish this when you found it? S

Re: SHA1 hash safety

2005-04-16 Thread Brian O'Mahoney
Three points: (1) I _have_ seen real-life collisions with MD5, in the context of Document management systems containing ~10^6 ms-WORD documents. (2) The HMAC (ethernet-harware-address) of any interface _should_ help to make a unique Id. (3) While I havn't looked at the details of the plumbi

Re: SHA1 hash safety

2005-04-16 Thread David Lang
On Sat, 16 Apr 2005, Ingo Molnar wrote: * David Lang <[EMAIL PROTECTED]> wrote: this issue was raised a few days ago in the context of someone tampering with the files and it was decided that the extra checks were good enough to prevent this (at least for now), but what about accidental collisions?

Re: SHA1 hash safety

2005-04-16 Thread Ingo Molnar
* David Lang <[EMAIL PROTECTED]> wrote: > this issue was raised a few days ago in the context of someone > tampering with the files and it was decided that the extra checks were > good enough to prevent this (at least for now), but what about > accidental collisions? > > if I am understanding

SHA1 hash safety

2005-04-16 Thread David Lang
this issue was raised a few days ago in the context of someone tampering with the files and it was decided that the extra checks were good enough to prevent this (at least for now), but what about accidental collisions? if I am understanding things right the objects get saved in the filesystem