jamesd@echeque.com writes:

At 08:35 AM 3/1/96 -0500, A. Padgett Peterson P.E. Information Security wrote :

...

Today, each person generates their own PGP key. While it is unlikely that any two will match, it is likely that at some point some two will match (see matching birthdays in a bar - number is less than you would think).

If if we colonized every planet in the galaxy, and every planet had a trillion people, and every single person on every planet generated a billion keys a second for a billion billion years, not one pair would match, assuming they were generated from truly random seeds.

Well, lets see. For a 1024 bit key, a birthday match is a 1 in 2^512 proposition, assuming that a key could be any random 1024 bit number. Assuming 100 million planets: 100000000*(10^12)*(10^9)*60*60*24*365*(10^9)*(10^9)= 3153600000000000000000000000000000000000000000000000000 2^512= 134078079299425970995740249982058461274793658205923933777235614437217\ 640300735469768018742981669034276900318581864860508537538828119465699\ 46433649006084096 However, the density of prime numbers isn't so high as to make the probability truly 1/2^512 -- indeed, I would guess it is much lower. However, you may indeed be right. None the less, one would hope that the software handled it gracefully even if the impossible happened... Perry