msm1267 writes: A challenge has been made against one of the conclusions in an academic paper on cryptographic weaknesses that may be the open door through which intelligence agencies are breaking encrypted connections. The paper, 'Imperfect Forward Secrecy: How Diffie-Hellman Fails in Practice,' claims that a massively resourced agency such as the NSA could build enough custom hardware that would crack the prime number used to derive an encryption key. Once enough information is known about the prime, breaking Diffie-Hellman connections that use that same prime is relatively trivial. In the paper, the team of 14 cryptographers and academics who wrote it claim that upwards of 66 percent of IPsec VPN connections can be passively decrypted in this manner. Paul Wouters, a founding member and core developer of the Libreswan Project, as well as a Red Hat associate, said that researchers are jumping to a conclusion because of the way they scanned and tested VPN servers, and that the number is likely too high.