SSL_CHECK_CHAIN(3ossl) OpenSSL SSL_CHECK_CHAIN(3ossl)
NAME
SSL_check_chain - check certificate chain suitability
SYNOPSIS
#include <openssl/ssl.h>
int SSL_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain);
DESCRIPTION
SSL_check_chain(3) checks whether certificate x, private key pk and
certificate chain chain is suitable for use with the current session s.
RETURN VALUES
SSL_check_chain(3) returns a bitmap of flags indicating the validity of
the chain.
CERT_PKEY_VALID: the chain can be used with the current session. If
this flag is not set then the certificate will never be used even if
the application tries to set it because it is inconsistent with the
peer preferences.
CERT_PKEY_SIGN: the EE key can be used for signing.
CERT_PKEY_EE_SIGNATURE: the signature algorithm of the EE certificate
is acceptable.
CERT_PKEY_CA_SIGNATURE: the signature algorithms of all CA certificates
are acceptable.
CERT_PKEY_EE_PARAM: the parameters of the end entity certificate are
acceptable (e.g. it is a supported curve).
CERT_PKEY_CA_PARAM: the parameters of all CA certificates are
acceptable.
CERT_PKEY_EXPLICIT_SIGN: the end entity certificate algorithm can be
used explicitly for signing (i.e. it is mentioned in the signature
algorithms extension).
CERT_PKEY_ISSUER_NAME: the issuer name is acceptable. This is only
meaningful for client authentication.
CERT_PKEY_CERT_TYPE: the certificate type is acceptable. Only
meaningful for client authentication.
CERT_PKEY_SUITEB: chain is suitable for Suite B use.
NOTES
SSL_check_chain(3) must be called in servers after a client hello
message or in clients after a certificate request message. It will
typically be called in the certificate callback.
An application wishing to support multiple certificate chains may call
this function on each chain in turn: starting with the one it considers
the most secure. It could then use the chain of the first set which
returns suitable flags.
As a minimum the flag CERT_PKEY_VALID must be set for a chain to be
usable. An application supporting multiple chains with different CA
signature algorithms may also wish to check CERT_PKEY_CA_SIGNATURE too.
If no chain is suitable a server should fall back to the most secure
chain which sets CERT_PKEY_VALID.
The validity of a chain is determined by checking if it matches a
supported signature algorithm, supported curves and in the case of
client authentication certificate types and issuer names.
Since the supported signature algorithms extension is only used in TLS
1.2, TLS 1.3 and DTLS 1.2 the results for earlier versions of TLS and
DTLS may not be very useful. Applications may wish to specify a
different "legacy" chain for earlier versions of TLS or DTLS.
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>.
3.3.2 2024-09-04 SSL_CHECK_CHAIN(3ossl)
openssl 3.3.2 - Generated Thu Sep 26 09:48:25 CDT 2024