SSL_CTX_load_verify_locations(3)SSL_CTX_load_verify_locations(3)NAMESSL_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
The SSL_CTX_load_verify_locations() function 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 the
following sequences:
-----BEGIN CERTIFICATE-----
... (CA certificate in base64 encoding) ...
-----END CERTIFICATE-----
Text is allowed before, between, and after the certificates. It can be
used, for example, to describe the certificates.
The CAfile is processed on execution of the SSL_CTX_load_verify_loca‐
tions() function.
If CApath is not NULL, it points to a directory containing CA certifi‐
cates in PEM format. The files each contain one CA certificate. The
files are looked up by the CA subject name hash value, which must 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 exten‐
sion 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, such as
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 parame‐
ters will be searched in case of failure.
In server mode, when requesting a client certificate, the server must
send the list of CAs from which it will accept client certificates.
This listis not influenced by the contents of CAfile or CApath and must
explicitly be set using the SSL_CTX_set_client_CA_list() 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 certifi‐
cate chain was not explicitly specified. (See
SSL_CTX_add_extra_chain_cert() and SSL_CTX_use_certificate().)
RESTRICTIONS
If several CA certificates matching the name, key identifier, and
serial number condition are available, only the first one will be exam‐
ined. 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. Do no
mix expired certificates with valid certificates.
RETURN VALUES
The following return values can occur: 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. The
operation succeeded.
EXAMPLES
Generate a CA certificate file with descriptive text from the CA cer‐
tificates 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 certifi‐
cates for use as CApath:
cd /some/where/certs
c_rehash .
SEE ALSO
Functions: 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)SSL_CTX_load_verify_locations(3)
