If sha-1 were a perfect cyptological hash, the probability of a hash collision for a given password would be 1 in 2^160, which, incidentally, is a huge, honking, big number. It isn't however, so the probability is a lttle less. Still, using all of the computing resources on earth the many, many millenia would take a lot of luck.
There are theoretical attacks on sha-1 that might enable generations of source string pairs with a probability of much less than 2^160, but this has nothing to do with sha-1 as a password hash. Jim Starkey > On Dec 8, 2014, at 7:02 AM, Mark Rotteveel <[email protected]> wrote: > > On Mon, 08 Dec 2014 13:44:36 +0300, Alex Peshkoff <[email protected]> > wrote: >> Yes. For password >20 bytes sooner of all exists shorter one with same >> hash value. > > But that is technically irrelevant. Although identical hashes are certain > due to pigeon holing, that doesn't mean shorter passwords (or passwords > near the hash length) are better than longer passwords. And even then, > making the assumption that most passwords only use characters between 0x20 > and 0x7E (95 characters out of potentially 256 in a byte) then a very rough > estimate is that identical hashes might only happen after 50 characters > (based on 256/95 * 20 = 53.9; a calculation that a cryptologist would > probably kill me for because it is either totally wrong or too > conservative). > > Mark > > ------------------------------------------------------------------------------ > Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server > from Actuate! Instantly Supercharge Your Business Reports and Dashboards > with Interactivity, Sharing, Native Excel Exports, App Integration & more > Get technology previously reserved for billion-dollar corporations, FREE > http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk > Firebird-Devel mailing list, web interface at > https://lists.sourceforge.net/lists/listinfo/firebird-devel ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
