Ah sure, that's why I said "irksome" and not "worrying" :-) It was more a curiosity of theoretical nature than a practical concern.
Enzo ----- Original Message ----- From: "Sidney Markowitz" <[EMAIL PROTECTED]> To: "Enzo Michelangeli" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Tuesday, November 18, 2003 3:48 PM Subject: Re: Are there...one-way encryption algorithms > Enzo Michelangeli wrote: > > but the slight risk of collision, > > although practically negligible, is a bit irksome > > If you quantify the "practically negligible" risk, it might be less > irksome: SHA-1 is a 160 bit hash. The birthday paradox says that you > would need to hash 2^80 different credit card numbers before you had a > 50% probability of having even one collision in your database keys. Very > roughly that means you would need to have a trillion different credit > card numbers in your database in order to get as much as a one in a > trillion chance of a collision. You would probably find dealing with a > trillion different credit card numbers more irksome than the negligible > chance of a collision even that many would give you. > > -- sidney > --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
