SSL_CTX_SET_CIPHER_LIST(3SSL)

📦
version 4.0.3 · 13 versions
, in ubuntu stonking

💖 SSL_CTX_SET_CIPHER_LIST 💖

okay so bestie, this is the OpenSSL page about picking your cipher vibes. The manpage name is SSL_CTX_SET_CIPHER_LIST(3SSL) and it covers SSL_CTX_set_cipher_list, SSL_set_cipher_list, SSL_CTX_set_ciphersuites, SSL_set_ciphersuites, OSSL_default_cipher_list, and OSSL_default_ciphersuites — aka all the functions that choose the list of available SSL_CIPHERs. ✨

🌸 SYNOPSIS 🌸

#include <openssl/ssl.h>

int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str);
int SSL_set_cipher_list(SSL *ssl, const char *str);

int SSL_CTX_set_ciphersuites(SSL_CTX *ctx, const char *str);
int SSL_set_ciphersuites(SSL *s, const char *str);

const char *OSSL_default_cipher_list(void);
const char *OSSL_default_ciphersuites(void);

🎀 DESCRIPTION 🎀

so SSL_CTX_set_cipher_list() sets the list of available ciphers (TLSv1.2 and below) for ctx using the control string str. The format of that string? It's described in openssl-ciphers(1), go look 💅. As of OpenSSL 4.0, str is processed case-insensitively. The list of ciphers gets inherited by every ssl object created from ctx, like heirlooms. It's giving legacy. This function does not affect TLSv1.3 ciphersuites — use SSL_CTX_set_ciphersuites() to configure those ones instead. And ctx MUST NOT be NULL. like, fr fr, MUST NOT. 🫶

SSL_set_cipher_list() sets the list of ciphers (TLSv1.2 and below) only for ssl. Just that one. Main character only.

SSL_CTX_set_ciphersuites() is the one you use to configure the available TLSv1.3 ciphersuites for ctx. It takes a simple colon (":") separated list of TLSv1.3 ciphersuite names, in order of preference. As of OpenSSL 4.0, str is processed case-insensitively. The valid TLSv1.3 ciphersuite names are:

TLS_AES_128_GCM_SHA256
TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_CCM_SHA256
TLS_AES_128_CCM_8_SHA256
TLS_SM4_GCM_SM3
TLS_SM4_CCM_SM3
TLS_SHA384_SHA384 - integrity-only
TLS_SHA256_SHA256 - integrity-only

An empty list is permissible 🫣. The default value for this setting is:

"TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256"

SSL_set_ciphersuites() is the same as SSL_CTX_set_ciphersuites() except it configures the ciphersuites for ssl (not the whole ctx). 🦋

OSSL_default_cipher_list() returns the default cipher string for TLSv1.2 (and earlier) ciphers. OSSL_default_ciphersuites() returns the default cipher string for TLSv1.3 ciphersuites. cute lil getters, obsessed. ⭐

✨ NOTES ✨

The control string str for SSL_CTX_set_cipher_list(), SSL_set_cipher_list(), SSL_CTX_set_ciphersuites() and SSL_set_ciphersuites() should be universally usable and not depend on details of the library configuration (ciphers compiled in). So no syntax checking takes place. Items that are not recognized — because the corresponding ciphers are not compiled in, or because they are mistyped — are simply ignored. Failure is only flagged if no ciphers could be collected at all. 😭

It should be noted that inclusion of a cipher to be used into the list is a necessary condition. On the client side, the inclusion into the list is also sufficient unless the security level excludes it. On the server side, additional restrictions apply. All ciphers have additional requirements:

  • ADH ciphers don't need a certificate, but DH-parameters must have been set.
  • All other ciphers need a corresponding certificate and key.

An RSA cipher can only be chosen when an RSA certificate is available. RSA ciphers using DHE need a certificate and key and additional DH-parameters (see SSL_CTX_set_tmp_dh_callback(3)).

A DSA cipher can only be chosen when a DSA certificate is available. DSA ciphers always use DH key exchange and therefore need DH-parameters (see SSL_CTX_set_tmp_dh_callback(3)).

⚠️ When these conditions are not met for any cipher in the list (e.g. a client only supports export RSA ciphers with an asymmetric key length of 512 bits and the server is not configured to use temporary RSA keys), the "no shared cipher" (SSL_R_NO_SHARED_CIPHER) error is generated and the handshake will fail. no cap, the handshake is DONE. 💀

OSSL_default_cipher_list() and OSSL_default_ciphersuites() replace SSL_DEFAULT_CIPHER_LIST and TLS_DEFAULT_CIPHERSUITES, respectively. The cipher list defines are deprecated as of 3.0. 🙈

💅 RETURN VALUES 💅

  • SSL_CTX_set_cipher_list() and SSL_set_cipher_list() return 1 if any cipher could be selected and 0 on complete failure.
  • SSL_CTX_set_ciphersuites() and SSL_set_ciphersuites() return 1 if the requested ciphersuite list was configured, and 0 otherwise.

🦋 SEE ALSO 🦋

ssl(7), SSL_get_ciphers(3), SSL_CTX_use_certificate(3), SSL_CTX_set_tmp_dh_callback(3), openssl-ciphers(1)

🌈 HISTORY 🌈

OSSL_default_cipher_list() and OSSL_default_ciphersites() are new in 3.0.

Cipher names were case-sensitive prior to OpenSSL 4.0.

Copyright 2000-2026 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

and that's the whole thing bestie, slay 🎀 mwah 💖 this was version 4.0.3, dated 2026-09-29, and it lives in the SSL_CTX_SET_CIPHER_LIST(3SSL) era. go configure ur ciphers, u got this. periodt. ✨💅

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