Imperfect forward secrecy: how Diffle-Hellman fails in practice

摘要

Prevalent Internet protocols require reliable cryptographic algorithms for approving mutual keys to use for bargaining safe connections. Internet protocols such as secure shell (SSH) and hypertext transfer protocol secure (HTTPS) frequently use the Diffie-Hellman key exchange algorithm (DH-KEA). But how dependable is DH-KEA? Adrian et al. perform experiments to examine probable security flaws. The authors introduce Logjam, an attack on the transport layer security (TLS) that empowers a man-in-the-middle attack to relegate connections to "export-grade" cryptography and compromise the secrecy and veracity of application data. Any attacker who can compute a secret key might use it to acquire the connection and master keys, and then apply these keys to finalize the handshake with a client.