Key Exchange

The cryptographic process by which two parties agree on a shared secret key over an insecure channel without transmitting the secret itself. The original Diffie-Hellman (DH) key exchange relies on the discrete logarithm problem; Elliptic Curve Diffie-Hellman (ECDHE) provides the same security with much shorter keys. TLS 1.3 supports only ECDHE and finite-field DH with ephemeral keys, ensuring forward secrecy. Post-quantum key exchange algorithms such as ML-KEM (Kyber) are being standardised by NIST and are already being deployed in hybrid TLS configurations.