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x SuSE Linux 13.1-RELEASEx
SSL_GET_SHARED_SIGALGS(3ossl) OpenSSL SSL_GET_SHARED_SIGALGS(3ossl)
NAME
SSL_get_shared_sigalgs, SSL_get_sigalgs - get supported signature
algorithms
SYNOPSIS
#include <openssl/ssl.h>
int SSL_get_shared_sigalgs(SSL *s, int idx,
int *psign, int *phash, int *psignhash,
unsigned char *rsig, unsigned char *rhash);
int SSL_get_sigalgs(SSL *s, int idx,
int *psign, int *phash, int *psignhash,
unsigned char *rsig, unsigned char *rhash);
DESCRIPTION
SSL_get_shared_sigalgs() returns information about the shared signature
algorithms supported by peer s. The parameter idx indicates the index
of the shared signature algorithm to return starting from zero. The
signature algorithm NID is written to *psign, the hash NID to *phash
and the sign and hash NID to *psignhash. The raw signature and hash
values are written to *rsig and *rhash.
SSL_get_sigalgs() is similar to SSL_get_shared_sigalgs() except it
returns information about all signature algorithms supported by s in
the order they were sent by the peer.
RETURN VALUES
SSL_get_shared_sigalgs() and SSL_get_sigalgs() return the number of
signature algorithms or 0 if the idx parameter is out of range.
NOTES
These functions are typically called for debugging purposes (to report
the peer's preferences) or where an application wants finer control
over certificate selection. Most applications will rely on internal
handling and will not need to call them.
If an application is only interested in the highest preference shared
signature algorithm it can just set idx to zero.
Any or all of the parameters psign, phash, psignhash, rsig or rhash can
be set to NULL if the value is not required. By setting them all to
NULL and setting idx to zero the total number of signature algorithms
can be determined: which can be zero.
These functions must be called after the peer has sent a list of
supported signature algorithms: after a client hello (for servers) or a
certificate request (for clients). They can (for example) be called in
the certificate callback.
Only TLS 1.2, TLS 1.3 and DTLS 1.2 currently support signature
algorithms. If these functions are called on an earlier version of TLS
or DTLS zero is returned.
The shared signature algorithms returned by SSL_get_shared_sigalgs()
are ordered according to configuration and peer preferences.
The raw values correspond to the on the wire form as defined by RFC5246
et al. The NIDs are OpenSSL equivalents. For example if the peer sent
sha256(4) and rsa(1) then *rhash would be 4, *rsign 1, *phash
NID_sha256, *psig NID_rsaEncryption and *psighash
NID_sha256WithRSAEncryption.
If a signature algorithm is not recognised the corresponding NIDs will
be set to NID_undef. This may be because the value is not supported, is
not an appropriate combination (for example MD5 and DSA) or the
signature algorithm does not use a hash (for example Ed25519).
SEE ALSO
SSL_CTX_set_cert_cb(3), ssl(7)
COPYRIGHT
Copyright 2015-2018 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>.
3.0.14 2024-06-04 SSL_GET_SHARED_SIGALGS(3ossl)
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