doc/man3/SSL_CTX_set1_sigalgs.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 SSL_CTX_set1_sigalgs, SSL_set1_sigalgs, SSL_CTX_set1_sigalgs_list,
   6 SSL_set1_sigalgs_list, SSL_CTX_set1_client_sigalgs,
   7 SSL_set1_client_sigalgs, SSL_CTX_set1_client_sigalgs_list,
   8 SSL_set1_client_sigalgs_list - set supported signature algorithms
   9
  10 =head1 SYNOPSIS
  11
  12  #include <openssl/ssl.h>
  13
  14  long SSL_CTX_set1_sigalgs(SSL_CTX *ctx, const int *slist, long slistlen);
  15  long SSL_set1_sigalgs(SSL *ssl, const int *slist, long slistlen);
  16  long SSL_CTX_set1_sigalgs_list(SSL_CTX *ctx, const char *str);
  17  long SSL_set1_sigalgs_list(SSL *ssl, const char *str);
  18
  19  long SSL_CTX_set1_client_sigalgs(SSL_CTX *ctx, const int *slist, long slistlen);
  20  long SSL_set1_client_sigalgs(SSL *ssl, const int *slist, long slistlen);
  21  long SSL_CTX_set1_client_sigalgs_list(SSL_CTX *ctx, const char *str);
  22  long SSL_set1_client_sigalgs_list(SSL *ssl, const char *str);
  23
  24 =head1 DESCRIPTION
  25
  26 SSL_CTX_set1_sigalgs() and SSL_set1_sigalgs() set the supported signature
  27 algorithms for B<ctx> or B<ssl>. The array B<slist> of length B<slistlen>
  28 must consist of pairs of NIDs corresponding to digest and public key
  29 algorithms.
  30
  31 SSL_CTX_set1_sigalgs_list() and SSL_set1_sigalgs_list() set the supported
  32 signature algorithms for B<ctx> or B<ssl>. The B<str> parameter
  33 must be a null terminated string consisting of a colon separated list of
  34 elements, where each element is either a combination of a public key
  35 algorithm and a digest separated by B<+>, or a TLS 1.3-style named
  36 SignatureScheme such as rsa_pss_pss_sha256. If a list entry is preceded
  37 with the C<?> character, it will be ignored if an implementation is missing.
  38
  39
  40 SSL_CTX_set1_client_sigalgs(), SSL_set1_client_sigalgs(),
  41 SSL_CTX_set1_client_sigalgs_list() and SSL_set1_client_sigalgs_list() set
  42 signature algorithms related to client authentication, otherwise they are
  43 identical to SSL_CTX_set1_sigalgs(), SSL_set1_sigalgs(),
  44 SSL_CTX_set1_sigalgs_list() and SSL_set1_sigalgs_list().
  45
  46 All these functions are implemented as macros. The signature algorithm
  47 parameter (integer array or string) is not freed: the application should
  48 free it, if necessary.
  49
  50 =head1 NOTES
  51
  52 If an application wishes to allow the setting of signature algorithms
  53 as one of many user configurable options it should consider using the more
  54 flexible SSL_CONF API instead.
  55
  56 The signature algorithms set by a client are used directly in the supported
  57 signature algorithm in the client hello message.
  58
  59 The supported signature algorithms set by a server are not sent to the
  60 client but are used to determine the set of shared signature algorithms
  61 and (if server preferences are set with SSL_OP_CIPHER_SERVER_PREFERENCE)
  62 their order.
  63
  64 The client authentication signature algorithms set by a server are sent
  65 in a certificate request message if client authentication is enabled,
  66 otherwise they are unused.
  67
  68 Similarly client authentication signature algorithms set by a client are
  69 used to determined the set of client authentication shared signature
  70 algorithms.
  71
  72 Signature algorithms will neither be advertised nor used if the security level
  73 prohibits them (for example SHA1 if the security level is 4 or more).
  74
  75 Currently the NID_md5, NID_sha1, NID_sha224, NID_sha256, NID_sha384 and
  76 NID_sha512 digest NIDs are supported and the public key algorithm NIDs
  77 EVP_PKEY_RSA, EVP_PKEY_RSA_PSS, EVP_PKEY_DSA and EVP_PKEY_EC.
  78
  79 The short or long name values for digests can be used in a string (for
  80 example "MD5", "SHA1", "SHA224", "SHA256", "SHA384", "SHA512") and
  81 the public key algorithm strings "RSA", "RSA-PSS", "DSA" or "ECDSA".
  82
  83 The TLS 1.3 signature scheme names (such as "rsa_pss_pss_sha256") can also
  84 be used with the B<_list> forms of the API.
  85
  86 The use of MD5 as a digest is strongly discouraged due to security weaknesses.
  87
  88 =head1 RETURN VALUES
  89
  90 All these functions return 1 for success and 0 for failure.
  91
  92 =head1 EXAMPLES
  93
  94 Set supported signature algorithms to SHA256 with ECDSA and SHA256 with RSA
  95 using an array:
  96
  97  const int slist[] = {NID_sha256, EVP_PKEY_EC, NID_sha256, EVP_PKEY_RSA};
  98
  99  SSL_CTX_set1_sigalgs(ctx, slist, 4);
 100
 101 Set supported signature algorithms to SHA256 with ECDSA and SHA256 with RSA
 102 using a string:
 103
 104  SSL_CTX_set1_sigalgs_list(ctx, "ECDSA+SHA256:RSA+SHA256");
 105
 106 =head1 SEE ALSO
 107
 108 L<ssl(7)>, L<SSL_get_shared_sigalgs(3)>,
 109 L<SSL_CONF_CTX_new(3)>
 110
 111 =head1 HISTORY
 112
 113 Support for ignoring unknown signature algorithms in
 114 SSL_CTX_set1_sigalgs_list(), SSL_set1_sigalgs_list(),
 115 SSL_CTX_set1_client_sigalgs_list() and SSL_set1_client_sigalgs_list()
 116 was added in OpenSSL 3.3.
 117
 118 =head1 COPYRIGHT
 119
 120 Copyright 2015-2024 The OpenSSL Project Authors. All Rights Reserved.
 121
 122 Licensed under the Apache License 2.0 (the "License").  You may not use
 123 this file except in compliance with the License.  You can obtain a copy
 124 in the file LICENSE in the source distribution or at
 125 L<https://www.openssl.org/source/license.html>.
 126
 127 =cut