According to The New York Times, a team of European and American researchers have discovered that some (about 0.2%) RSA public keys are insecure. The insecurity is the result of using prime factors that aren’t cryptographically random. I’m still reading the paper but it appears that poor random number generation resulted in shared factors between many of the keys and in many cases shared moduli. One group of keys sharing a modulus had 16,489 keys in it.
It’s an interesting paper and worth a read if you’re interested in cryptography and security. One startling fact from the paper is that the authors used “unsophisticated methods” in their work and said they find it hard to believe that their results haven’t already been used for exploits.