SSL_CTX_load_verify_locationsOpenSSL_CTX_load_verify_locations(3)
SSL_CTX_load_verify_locations - set default locations for
trusted CA certificates
libcrypto, -lcrypto
#include <openssl/ssl.h>
int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *CAfile,
const char *CApath);
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.
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).
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.
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 .
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.
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)
2002-06-10 0.9SSL_CTX_load_verify_locations(3)
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