Cipher Suite

TLS cipher suites, the basis of the encryption agreement between EDI partners.

Definition

The client lists its supported cipher suites in the ClientHello; the server selects one in the ServerHello. In TLS 1.2 (RFC 5246) a suite covers key exchange, authentication, cipher and MAC; in TLS 1.3 (RFC 8446) it describes only the AEAD cipher and hash, with key exchange negotiated separately. No common suite means the handshake fails — a frequent incident when an EDI partner hardens its config and drops weak suites.

Origin

Values are listed in the IANA "TLS Cipher Suites" registry. Negotiation is specified by RFC 5246 (TLS 1.2) and RFC 8446 (TLS 1.3, which obsoletes RFC 5246).

Example in context

An AS2 partner mandates TLS_AES_128_GCM_SHA256 (TLS 1.3); a client offering only TLS_RSA_WITH_AES_128_CBC_SHA (TLS 1.2, removed) receives a handshake_failure.

Related terms

• TLS 1.3 — version with the simplified suite format.