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Cipher suite

A named combination of cryptographic algorithms used by a TLS connection; in TLS 1.3 it names only the AEAD and the handshake hash (for example TLS_AES_128_GCM_SHA256), while TLS 1.2 names also fixed the key exchange and authentication.
Also written ascipher suiteciphersuiteTLS_AES_128_GCM_SHA256

TLS 1.3 defines five suites: TLS_AES_128_GCM_SHA256 (0x1301), TLS_AES_256_GCM_SHA384 (0x1302), TLS_CHACHA20_POLY1305_SHA256 (0x1303), TLS_AES_128_CCM_SHA256 (0x1304) and TLS_AES_128_CCM_8_SHA256 (0x1305). Key exchange and signature algorithms are negotiated separately through supported_groups and signature_algorithms.

TLS 1.2 names encode everything, for example TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (0xC02B): ECDHE key exchange, ECDSA authentication, AES-128-GCM, SHA-256 for the PRF. RFC 9325 recommends only ECDHE or DHE with AEAD suites for TLS 1.2; RSA key transport, CBC suites, RC4, 3DES and export suites are all deprecated.

OpenSSL configures the two lists separately (-ciphersuites for TLS 1.3, -cipher for TLS 1.2 and below) and uses its own names (ECDHE-ECDSA-AES128-GCM-SHA256). The TLS configuration generator produces current server settings.

Standards and references

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