SSL_CTX_load_verify_locations - set default locations for trusted CA
int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *CAfile,
const char *CApath);
specifies the locations for ctx
at which CA certificates for verification purposes are located. The
certificates available via CAfile
is not NULL, it points to a file of CA certificates in PEM
format. The file can contain several CA certificates identified by
... (CA certificate in base64 encoding) ...
sequences. Before, between, and after the certificates text is allowed which can
be used e.g. for descriptions of the certificates.
is processed on execution of the
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
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
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
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
explicitly be set using the SSL_CTX_set_client_CA_list(3)
When building its own certificate chain, an OpenSSL client/server will try to
fill in missing certificates from CAfile
, if the
certificate chain was not explicitly specified (see
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:
for i in ca1.pem ca2.pem ca3.pem ; do
openssl x509 -in $i -text >> CAfile.pem
Prepare the directory /some/where/certs containing several CA certificates for
use as CApath
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.