NAME¶
SSL_CTX_load_verify_locations - set default locations for trusted CA
certificates
SYNOPSIS¶
#include <openssl/ssl.h>
int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *CAfile,
const char *CApath);
DESCRIPTION¶
SSL_CTX_load_verify_locations() specifies the locations for
ctx,
at which CA certificates for verification purposes are located. The
certificates available via
CAfile and
CApath are trusted.
NOTES¶
If
CAfile is not NULL, it points to a file of CA certificates in PEM
format. The file can contain several CA certificates identified by
-----BEGIN CERTIFICATE-----
... (CA certificate in base64 encoding) ...
-----END CERTIFICATE-----
sequences. Before, between, and after the certificates text is allowed which can
be used e.g. for descriptions of the certificates.
The
CAfile is processed on execution of the
SSL_CTX_load_verify_locations() function.
If
CApath is not NULL, it points to a directory containing CA
certificates in PEM format. The files each contain one CA certificate. The
files are looked up by the CA subject name hash value, which must hence be
available. If more than one CA certificate with the same name hash value
exist, the extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The
search is performed in the ordering of the extension number, regardless of
other properties of the certificates. Use the
c_rehash utility to
create the necessary links.
The certificates in
CApath are only looked up when required, e.g. when
building the certificate chain or when actually performing the verification of
a peer certificate.
When looking up CA certificates, the OpenSSL library will first search the
certificates in
CAfile, then those in
CApath. Certificate
matching is done based on the subject name, the key identifier (if present),
and the serial number as taken from the certificate to be verified. If these
data do not match, the next certificate will be tried. If a first certificate
matching the parameters is found, the verification process will be performed;
no other certificates for the same parameters will be searched in case of
failure.
In server mode, when requesting a client certificate, the server must send the
list of CAs of which it will accept client certificates. This list is not
influenced by the contents of
CAfile or
CApath and must
explicitly be set using the
SSL_CTX_set_client_CA_list(3) family of
functions.
When building its own certificate chain, an OpenSSL client/server will try to
fill in missing certificates from
CAfile/
CApath, if the
certificate chain was not explicitly specified (see
SSL_CTX_add_extra_chain_cert(3),
SSL_CTX_use_certificate(3).
WARNINGS¶
If several CA certificates matching the name, key identifier, and serial number
condition are available, only the first one will be examined. This may lead to
unexpected results if the same CA certificate is available with different
expiration dates. If a "certificate expired" verification error
occurs, no other certificate will be searched. Make sure to not have expired
certificates mixed with valid ones.
EXAMPLES¶
Generate a CA certificate file with descriptive text from the CA certificates
ca1.pem ca2.pem ca3.pem:
#!/bin/sh
rm CAfile.pem
for i in ca1.pem ca2.pem ca3.pem ; do
openssl x509 -in $i -text >> CAfile.pem
done
Prepare the directory /some/where/certs containing several CA certificates for
use as
CApath:
cd /some/where/certs
c_rehash .
RETURN VALUES¶
The following return values can occur:
- 0
- The operation failed because CAfile and CApath are NULL or
the processing at one of the locations specified failed. Check the error
stack to find out the reason.
- 1
- The operation succeeded.
SEE ALSO¶
ssl(3),
SSL_CTX_set_client_CA_list(3),
SSL_get_client_CA_list(3),
SSL_CTX_use_certificate(3),
SSL_CTX_add_extra_chain_cert(3),
SSL_CTX_set_cert_store(3)