protéger Firefox contre la faille ssl logjam (https://weakdh.org/
Disable the insecure ciphers here:
(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.
(2) In the search box above the list, type or paste ssl3 and pause while the list is filtered
(3) Double-click the security.ssl3.dhe_rsa_aes_128_sha preference to switch it from true to false (this usually would be the first item on the list)
(4) Double-click the security.ssl3.dhe_rsa_aes_256_sha preference to switch it from true to false (this usually would be the second item on the list)
That's it, you can test using: https://www.ssllabs.com/ssltest/viewMyClient.html