FFC-DH Peer Validation Uses Attacker-Supplied q

Issue summary: When EVPPKEYderivesetpeer is called with a DHX X9.42 peer key, the peer key is not properly checked for the subgroup membership. Impact summary: A malicious peer which presents an X9.42 key carrying the victim’s p and g parameters, a forged q = r a small prime factor of the cofacto...

OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

Usual Mandatory Disclaimer: IANAC I am not a cryptographer so I might likely end up writing a bunch of mistakes in this blog post... tl;dr The OpenSSL 1.0.2 releases suffer from a Key Recovery Attack on DH small subgroups. This issue got assigned CVE-2016-0701 with a severity of High and OpenSSL...