1=pod
2
3=head1 NAME
4
5X509_LOOKUP_hash_dir, X509_LOOKUP_file,
6X509_load_cert_file,
7X509_load_crl_file,
8X509_load_cert_crl_file - Default OpenSSL certificate
9lookup methods
10
11=head1 SYNOPSIS
12
13 #include <openssl/x509_vfy.h>
14
15 X509_LOOKUP_METHOD *X509_LOOKUP_hash_dir(void);
16 X509_LOOKUP_METHOD *X509_LOOKUP_file(void);
17
18 int X509_load_cert_file(X509_LOOKUP *ctx, const char *file, int type);
19 int X509_load_crl_file(X509_LOOKUP *ctx, const char *file, int type);
20 int X509_load_cert_crl_file(X509_LOOKUP *ctx, const char *file, int type);
21
22=head1 DESCRIPTION
23
24B<X509_LOOKUP_hash_dir> and B<X509_LOOKUP_file> are two certificate
25lookup methods to use with B<X509_STORE>, provided by OpenSSL library.
26
27Users of the library typically do not need to create instances of these
28methods manually, they would be created automatically by
29L<X509_STORE_load_locations(3)> or
30L<SSL_CTX_load_verify_locations(3)>
31functions.
32
33Internally loading of certificates and CRLs is implemented via functions
34B<X509_load_cert_crl_file>, B<X509_load_cert_file> and
35B<X509_load_crl_file>. These functions support parameter I<type>, which
36can be one of constants B<FILETYPE_PEM>, B<FILETYPE_ASN1> and
37B<FILETYPE_DEFAULT>. They load certificates and/or CRLs from specified
38file into memory cache of B<X509_STORE> objects which given B<ctx>
39parameter is associated with.
40
41Functions B<X509_load_cert_file> and
42B<X509_load_crl_file> can load both PEM and DER formats depending of
43type value. Because DER format cannot contain more than one certificate
44or CRL object (while PEM can contain several concatenated PEM objects)
45B<X509_load_cert_crl_file> with B<FILETYPE_ASN1> is equivalent to
46B<X509_load_cert_file>.
47
48Constant B<FILETYPE_DEFAULT> with NULL filename causes these functions
49to load default certificate store file (see
50L<X509_STORE_set_default_paths(3)>.
51
52
53Functions return number of objects loaded from file or 0 in case of
54error.
55
56Both methods support adding several certificate locations into one
57B<X509_STORE>.
58
59This page documents certificate store formats used by these methods and
60caching policy.
61
62=head2 File Method
63
64The B<X509_LOOKUP_file> method loads all the certificates or CRLs
65present in a file into memory at the time the file is added as a
66lookup source.
67
68File format is ASCII text which contains concatenated PEM certificates
69and CRLs.
70
71This method should be used by applications which work with a small
72set of CAs.
73
74=head2 Hashed Directory Method
75
76B<X509_LOOKUP_hash_dir> is a more advanced method, which loads
77certificates and CRLs on demand, and caches them in memory once
78they are loaded. As of OpenSSL 1.0.0, it also checks for newer CRLs
79upon each lookup, so that newer CRLs are as soon as they appear in
80the directory.
81
82The directory should contain one certificate or CRL per file in PEM format,
83with a file name of the form I<hash>.I<N> for a certificate, or
84I<hash>.B<r>I<N> for a CRL.
85The I<hash> is the value returned by the L<X509_NAME_hash(3)> function applied
86to the subject name for certificates or issuer name for CRLs.
87The hash can also be obtained via the B<-hash> option of the L<x509(1)> or
88L<crl(1)> commands.
89
90The .I<N> or .B<r>I<N> suffix is a sequence number that starts at zero, and is
91incremented consecutively for each certificate or CRL with the same I<hash>
92value.
93Gaps in the sequence numbers are not supported, it is assumed that there are no
94more objects with the same hash beyond the first missing number in the
95sequence.
96
97Sequence numbers make it possible for the directory to contain multiple
98certificates with same subject name hash value.
99For example, it is possible to have in the store several certificates with same
100subject or several CRLs with same issuer (and, for example, different validity
101period).
102
103When checking for new CRLs once one CRL for given hash value is
104loaded, hash_dir lookup method checks only for certificates with
105sequence number greater than that of the already cached CRL.
106
107Note that the hash algorithm used for subject name hashing changed in OpenSSL
1081.0.0, and all certificate stores have to be rehashed when moving from OpenSSL
1090.9.8 to 1.0.0.
110
111OpenSSL includes a L<rehash(1)> utility which creates symlinks with correct
112hashed names for all files with .pem suffix in a given directory.
113
114=head1 RETURN VALUES
115
116X509_LOOKUP_hash_dir() and X509_LOOKUP_file() always return a valid
117B<X509_LOOKUP_METHOD> structure.
118
119X509_load_cert_file(), X509_load_crl_file() and X509_load_cert_crl_file() return
120the number of loaded objects or 0 on error.
121
122=head1 SEE ALSO
123
124L<PEM_read_PrivateKey(3)>,
125L<X509_STORE_load_locations(3)>,
126L<X509_store_add_lookup(3)>,
127L<SSL_CTX_load_verify_locations(3)>,
128L<X509_LOOKUP_meth_new(3)>,
129
130=head1 COPYRIGHT
131
132Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved.
133
134Licensed under the OpenSSL license (the "License").  You may not use
135this file except in compliance with the License.  You can obtain a copy
136in the file LICENSE in the source distribution or at
137L<https://www.openssl.org/source/license.html>.
138
139=cut
140