1=pod
2
3=head1 NAME
4
5SSL_CTX_load_verify_locations, SSL_CTX_set_default_verify_paths,
6SSL_CTX_set_default_verify_dir, SSL_CTX_set_default_verify_file - set
7default locations for trusted CA certificates
8
9=head1 SYNOPSIS
10
11 #include <openssl/ssl.h>
12
13 int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *CAfile,
14                                   const char *CApath);
15
16 int SSL_CTX_set_default_verify_paths(SSL_CTX *ctx);
17
18 int SSL_CTX_set_default_verify_dir(SSL_CTX *ctx);
19
20 int SSL_CTX_set_default_verify_file(SSL_CTX *ctx);
21
22=head1 DESCRIPTION
23
24SSL_CTX_load_verify_locations() specifies the locations for B<ctx>, at
25which CA certificates for verification purposes are located. The certificates
26available via B<CAfile> and B<CApath> are trusted.
27
28SSL_CTX_set_default_verify_paths() specifies that the default locations from
29which CA certificates are loaded should be used. There is one default directory
30and one default file. The default CA certificates directory is called "certs" in
31the default OpenSSL directory. Alternatively the SSL_CERT_DIR environment
32variable can be defined to override this location. The default CA certificates
33file is called "cert.pem" in the default OpenSSL directory. Alternatively the
34SSL_CERT_FILE environment variable can be defined to override this location.
35
36SSL_CTX_set_default_verify_dir() is similar to
37SSL_CTX_set_default_verify_paths() except that just the default directory is
38used.
39
40SSL_CTX_set_default_verify_file() is similar to
41SSL_CTX_set_default_verify_paths() except that just the default file is
42used.
43
44=head1 NOTES
45
46If B<CAfile> is not NULL, it points to a file of CA certificates in PEM
47format. The file can contain several CA certificates identified by
48
49 -----BEGIN CERTIFICATE-----
50 ... (CA certificate in base64 encoding) ...
51 -----END CERTIFICATE-----
52
53sequences. Before, between, and after the certificates text is allowed
54which can be used e.g. for descriptions of the certificates.
55
56The B<CAfile> is processed on execution of the SSL_CTX_load_verify_locations()
57function.
58
59If B<CApath> is not NULL, it points to a directory containing CA certificates
60in PEM format. The files each contain one CA certificate. The files are
61looked up by the CA subject name hash value, which must hence be available.
62If more than one CA certificate with the same name hash value exist, the
63extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search
64is performed in the ordering of the extension number, regardless of other
65properties of the certificates.
66Use the B<c_rehash> utility to create the necessary links.
67
68The certificates in B<CApath> are only looked up when required, e.g. when
69building the certificate chain or when actually performing the verification
70of a peer certificate.
71
72When looking up CA certificates, the OpenSSL library will first search the
73certificates in B<CAfile>, then those in B<CApath>. Certificate matching
74is done based on the subject name, the key identifier (if present), and the
75serial number as taken from the certificate to be verified. If these data
76do not match, the next certificate will be tried. If a first certificate
77matching the parameters is found, the verification process will be performed;
78no other certificates for the same parameters will be searched in case of
79failure.
80
81In server mode, when requesting a client certificate, the server must send
82the list of CAs of which it will accept client certificates. This list
83is not influenced by the contents of B<CAfile> or B<CApath> and must
84explicitly be set using the
85L<SSL_CTX_set_client_CA_list(3)>
86family of functions.
87
88When building its own certificate chain, an OpenSSL client/server will
89try to fill in missing certificates from B<CAfile>/B<CApath>, if the
90certificate chain was not explicitly specified (see
91L<SSL_CTX_add_extra_chain_cert(3)>,
92L<SSL_CTX_use_certificate(3)>.
93
94=head1 WARNINGS
95
96If several CA certificates matching the name, key identifier, and serial
97number condition are available, only the first one will be examined. This
98may lead to unexpected results if the same CA certificate is available
99with different expiration dates. If a "certificate expired" verification
100error occurs, no other certificate will be searched. Make sure to not
101have expired certificates mixed with valid ones.
102
103=head1 EXAMPLES
104
105Generate a CA certificate file with descriptive text from the CA certificates
106ca1.pem ca2.pem ca3.pem:
107
108 #!/bin/sh
109 rm CAfile.pem
110 for i in ca1.pem ca2.pem ca3.pem ; do
111     openssl x509 -in $i -text >> CAfile.pem
112 done
113
114Prepare the directory /some/where/certs containing several CA certificates
115for use as B<CApath>:
116
117 cd /some/where/certs
118 c_rehash .
119
120=head1 RETURN VALUES
121
122For SSL_CTX_load_verify_locations the following return values can occur:
123
124=over 4
125
126=item Z<>0
127
128The operation failed because B<CAfile> and B<CApath> are NULL or the
129processing at one of the locations specified failed. Check the error
130stack to find out the reason.
131
132=item Z<>1
133
134The operation succeeded.
135
136=back
137
138SSL_CTX_set_default_verify_paths(), SSL_CTX_set_default_verify_dir() and
139SSL_CTX_set_default_verify_file() all return 1 on success or 0 on failure. A
140missing default location is still treated as a success.
141
142=head1 SEE ALSO
143
144L<ssl(7)>,
145L<SSL_CTX_set_client_CA_list(3)>,
146L<SSL_get_client_CA_list(3)>,
147L<SSL_CTX_use_certificate(3)>,
148L<SSL_CTX_add_extra_chain_cert(3)>,
149L<SSL_CTX_set_cert_store(3)>,
150L<SSL_CTX_set_client_CA_list(3)>
151
152=head1 COPYRIGHT
153
154Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
155
156Licensed under the OpenSSL license (the "License").  You may not use
157this file except in compliance with the License.  You can obtain a copy
158in the file LICENSE in the source distribution or at
159L<https://www.openssl.org/source/license.html>.
160
161=cut
162