DHEECDHE

DHEECDHE is not an official algorithm name in widely used cryptographic standards. In practice, the term is often used informally to refer to the family of ephemeral Diffie-Hellman key exchange methods used in secure communications, particularly DHE and ECDHE. Both approaches enable two parties to establish a shared secret over an insecure channel with forward secrecy: the session keys are derived from ephemeral private keys that are discarded after the handshake, so a future compromise of the server’s private key does not reveal past communications.

DHE stands for Diffie-Hellman Ephemeral and uses a finite-field Diffie-Hellman setup with a prime modulus and a generator. ECDHE stands for Elliptic Curve Diffie-Hellman Ephemeral and uses elliptic curves, which typically provide equivalent security with much smaller key sizes. In practice this means ECDHE can achieve similar levels of security with smaller keys and faster computations, though both rely on carefully chosen parameters to remain secure.

In deployment, DHE and ECDHE are commonly seen within TLS cipher suites. Examples include TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 and TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256. Modern configurations generally favor ECDHE for performance and smaller handshake messages, while ensuring that strong, validated curves (such as Curve25519/X25519 or secp256r1) are used and that vulnerable groups (like very small DH moduli) are disabled.

See also: TLS, Diffie-Hellman, Elliptic Curve Cryptography, forward secrecy.