CipherSuitesVerhandlungen

Cipher suites are named collections of cryptographic algorithms used to secure a TLS/SSL connection. Each suite specifies the algorithms for key exchange, server authentication, bulk encryption, and data integrity. In TLS 1.2 and earlier, a cipher suite typically includes four components: a key exchange method (for example RSA, DHE, or ECDHE), an authentication method (such as RSA or ECDSA), a bulk encryption algorithm (for example AES_128_GCM, AES_256_CBC, or ChaCha20-Poly1305), and a message authentication code or AEAD construction (for example SHA256 or SHA384).

TLS 1.3 simplifies the model by removing the separate MAC and some legacy configurations. The cipher suites in TLS 1.3 focus on the chosen AEAD algorithm and a HKDF hash, with common examples including TLS_AES_128_GCM_SHA256, TLS_AES_256_GCM_SHA384, and TLS_CHACHA20_POLY1305_SHA256.

Negotiation happens during the TLS handshake: the client sends a list of supported cipher suites, and the server selects one that it also supports. The chosen suite governs the encryption and integrity properties for the session. Administrators often enforce a preferred order or minimum security policy and should disable legacy suites and protocols in favor of modern configurations.

Security considerations: many older suites use weak or deprecated primitives, such as RC4, 3DES, CBC modes with problematic padding, or RSA key exchange without forward secrecy. Best practice is to prefer TLS 1.3 when possible, or TLS 1.2 configurations that use AEAD ciphers with forward secrecy and strong hashes, and to keep server libraries up to date.

Operational notes: cipher suite support is exercised by servers, clients, and middleboxes; accurate configuration helps mitigate downgrade and configuration error risks. Regular audits and testing with reputable scanners help ensure alignment with current security guidance.