SSL_CTX_load_verify_locations manpage

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SSL_CTX_load_verify_locations(3)    OpenSSL   SSL_CTX_load_verify_locations(3)

       SSL_CTX_load_verify_locations - set default locations for trusted CA

	#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

	... (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.

       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

       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:

	rm CAfile.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:

	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),

1.0.2k				  2017-01-26  SSL_CTX_load_verify_locations(3)