5 X509_LOOKUP_hash_dir, X509_LOOKUP_file, X509_LOOKUP_store,
6 X509_load_cert_file_with_libctx, X509_load_cert_file,
8 X509_load_cert_crl_file_with_libctx, X509_load_cert_crl_file
9 - Default OpenSSL certificate lookup methods
13 #include <openssl/x509_vfy.h>
15 X509_LOOKUP_METHOD *X509_LOOKUP_hash_dir(void);
16 X509_LOOKUP_METHOD *X509_LOOKUP_file(void);
17 X509_LOOKUP_METHOD *X509_LOOKUP_store(void);
19 int X509_load_cert_file_with_libctx(X509_LOOKUP *ctx, const char *file,
20 int type, OPENSSL_CTX *libctx,
22 int X509_load_cert_file(X509_LOOKUP *ctx, const char *file, int type);
23 int X509_load_crl_file(X509_LOOKUP *ctx, const char *file, int type);
24 int X509_load_cert_crl_file_with_libctx(X509_LOOKUP *ctx, const char *file,
25 int type, OPENSSL_CTX *libctx,
27 int X509_load_cert_crl_file(X509_LOOKUP *ctx, const char *file, int type);
31 B<X509_LOOKUP_hash_dir> and B<X509_LOOKUP_file> are two certificate
32 lookup methods to use with B<X509_STORE>, provided by OpenSSL library.
34 Users of the library typically do not need to create instances of these
35 methods manually, they would be created automatically by
36 L<X509_STORE_load_locations(3)> or
37 L<SSL_CTX_load_verify_locations(3)>
40 Internally loading of certificates and CRLs is implemented via functions
41 B<X509_load_cert_crl_file>, B<X509_load_cert_file> and
42 B<X509_load_crl_file>. These functions support parameter I<type>, which
43 can be one of constants B<FILETYPE_PEM>, B<FILETYPE_ASN1> and
44 B<FILETYPE_DEFAULT>. They load certificates and/or CRLs from specified
45 file into memory cache of B<X509_STORE> objects which given B<ctx>
46 parameter is associated with.
48 Functions B<X509_load_cert_file> and
49 B<X509_load_crl_file> can load both PEM and DER formats depending of
50 type value. Because DER format cannot contain more than one certificate
51 or CRL object (while PEM can contain several concatenated PEM objects)
52 B<X509_load_cert_crl_file> with B<FILETYPE_ASN1> is equivalent to
53 B<X509_load_cert_file>.
55 Constant B<FILETYPE_DEFAULT> with NULL filename causes these functions
56 to load default certificate store file (see
57 L<X509_STORE_set_default_paths(3)>.
60 Functions return number of objects loaded from file or 0 in case of
63 Both methods support adding several certificate locations into one
66 This page documents certificate store formats used by these methods and
71 The B<X509_LOOKUP_file> method loads all the certificates or CRLs
72 present in a file into memory at the time the file is added as a
75 File format is ASCII text which contains concatenated PEM certificates
78 This method should be used by applications which work with a small
81 =head2 Hashed Directory Method
83 B<X509_LOOKUP_hash_dir> is a more advanced method, which loads
84 certificates and CRLs on demand, and caches them in memory once
85 they are loaded. As of OpenSSL 1.0.0, it also checks for newer CRLs
86 upon each lookup, so that newer CRLs are as soon as they appear in
89 The directory should contain one certificate or CRL per file in PEM format,
90 with a filename of the form I<hash>.I<N> for a certificate, or
91 I<hash>.B<r>I<N> for a CRL.
92 The I<hash> is the value returned by the L<X509_NAME_hash(3)> function applied
93 to the subject name for certificates or issuer name for CRLs.
94 The hash can also be obtained via the B<-hash> option of the
95 L<openssl-x509(1)> or L<openssl-crl(1)> commands.
97 The .I<N> or .B<r>I<N> suffix is a sequence number that starts at zero, and is
98 incremented consecutively for each certificate or CRL with the same I<hash>
100 Gaps in the sequence numbers are not supported, it is assumed that there are no
101 more objects with the same hash beyond the first missing number in the
104 Sequence numbers make it possible for the directory to contain multiple
105 certificates with same subject name hash value.
106 For example, it is possible to have in the store several certificates with same
107 subject or several CRLs with same issuer (and, for example, different validity
110 When checking for new CRLs once one CRL for given hash value is
111 loaded, hash_dir lookup method checks only for certificates with
112 sequence number greater than that of the already cached CRL.
114 Note that the hash algorithm used for subject name hashing changed in OpenSSL
115 1.0.0, and all certificate stores have to be rehashed when moving from OpenSSL
118 OpenSSL includes a L<openssl-rehash(1)> utility which creates symlinks with
119 hashed names for all files with F<.pem> suffix in a given directory.
121 =head2 OSSL_STORE Method
123 B<X509_LOOKUP_store> is a method that allows access to any store of
124 certificates and CRLs through any loader supported by
126 It works with the help of URIs, which can be direct references to
127 certificates or CRLs, but can also be references to catalogues of such
128 objects (that behave like directories).
130 This method overlaps the L</File Method> and L</Hashed Directory Method>
131 because of the 'file:' scheme loader.
132 It does no caching of its own, but can use a caching L<ossl_store(7)>
133 loader, and therefore depends on the loader's capability.
137 X509_LOOKUP_hash_dir(), X509_LOOKUP_file() and X509_LOOKUP_store()
138 always return a valid B<X509_LOOKUP_METHOD> structure.
140 X509_load_cert_file(), X509_load_crl_file() and X509_load_cert_crl_file() return
141 the number of loaded objects or 0 on error.
145 L<PEM_read_PrivateKey(3)>,
146 L<X509_STORE_load_locations(3)>,
147 L<X509_store_add_lookup(3)>,
148 L<SSL_CTX_load_verify_locations(3)>,
149 L<X509_LOOKUP_meth_new(3)>,
154 The functions X509_load_cert_file_with_libctx(),
155 X509_load_cert_crl_file_with_libctx() and X509_LOOKUP_store() were added in
160 Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
162 Licensed under the Apache License 2.0 (the "License"). You may not use
163 this file except in compliance with the License. You can obtain a copy
164 in the file LICENSE in the source distribution or at
165 L<https://www.openssl.org/source/license.html>.