{"action":"opened","issue":{"url":"https://api.github.com/repos/aeris/cryptcheck/issues/14","labels_url":"https://api.github.com/repos/aeris/cryptcheck/issues/14/labels{/name}","comments_url":"https://api.github.com/repos/aeris/cryptcheck/issues/14/comments","events_url":"https://api.github.com/repos/aeris/cryptcheck/issues/14/events","html_url":"https://github.com/aeris/cryptcheck/issues/14","id":117797446,"number":14,"title":"ECDH doesn't seem to enable forward secrecy","user":{"login":"bbc2","id":1645335,"avatar_url":"https://avatars.githubusercontent.com/u/1645335?v=3","gravatar_id":"","url":"https://api.github.com/users/bbc2","html_url":"https://github.com/bbc2","followers_url":"https://api.github.com/users/bbc2/followers","following_url":"https://api.github.com/users/bbc2/following{/other_user}","gists_url":"https://api.github.com/users/bbc2/gists{/gist_id}","starred_url":"https://api.github.com/users/bbc2/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bbc2/subscriptions","organizations_url":"https://api.github.com/users/bbc2/orgs","repos_url":"https://api.github.com/users/bbc2/repos","events_url":"https://api.github.com/users/bbc2/events{/privacy}","received_events_url":"https://api.github.com/users/bbc2/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-11-19T11:51:33Z","updated_at":"2015-11-19T11:51:33Z","closed_at":null,"body":"On https://tls.imirhil.fr/ciphers, I can see that cipher suites like ECDH-ECDSA-AES256-GCM-SHA384 have the `PFS` badge.  However, unlike suites using ECDHE, they don't seem to enable forward secrecy because the server certificate is supposed to contain a Diffie-Hellman key [1].  Therefore, if you compromise the server at a later time, I think you can recover the exchanged secret from the server DH private key and the (optionally ephemeral [2]) client DH public key sent on the wire.\r\n\r\nThat's not a proof but I guess it makes this ECDH algorithm worthy of further investigation, to remove the `PFS` badge if necessary.\r\n\r\n[1] https://tools.ietf.org/html/rfc4492#section-2.1\r\n[2] https://tools.ietf.org/html/rfc4492#section-3.2"}}