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=head1 NAME

X509_LOOKUP_hash_dir, X509_LOOKUP_file,

X509_load_cert_file,

X509_load_crl_file,

X509_load_cert_crl_file - Default OpenSSL certificate

lookup methods

=head1 SYNOPSIS

 #include <openssl/x509_vfy.h>

 X509_LOOKUP_METHOD *X509_LOOKUP_hash_dir(void);

 X509_LOOKUP_METHOD *X509_LOOKUP_file(void);

 int X509_load_cert_file(X509_LOOKUP *ctx, const char *file, int type);

 int X509_load_crl_file(X509_LOOKUP *ctx, const char *file, int type);

 int X509_load_cert_crl_file(X509_LOOKUP *ctx, const char *file, int type);

=head1 DESCRIPTION

B<X509_LOOKUP_hash_dir> and B<X509_LOOKUP_file> are two certificate

lookup methods to use with B<X509_STORE>, provided by OpenSSL library.

Users of the library typically do not need to create instances of these

methods manually, they would be created automatically by

L<X509_STORE_load_locations(3)> or

L<SSL_CTX_load_verify_locations(3)>

functions.

Internally loading of certificates and CRLs is implemented via functions

B<X509_load_cert_crl_file>, B<X509_load_cert_file> and

B<X509_load_crl_file>. These functions support parameter I<type>, which

can be one of constants B<FILETYPE_PEM>, B<FILETYPE_ASN1> and

B<FILETYPE_DEFAULT>. They load certificates and/or CRLs from specified

file into memory cache of B<X509_STORE> objects which given B<ctx>

parameter is associated with.

Functions B<X509_load_cert_file> and

B<X509_load_crl_file> can load both PEM and DER formats depending of

type value. Because DER format cannot contain more than one certificate

or CRL object (while PEM can contain several concatenated PEM objects)

B<X509_load_cert_crl_file> with B<FILETYPE_ASN1> is equivalent to

B<X509_load_cert_file>.

Constant B<FILETYPE_DEFAULT> with NULL filename causes these functions

to load default certificate store file (see

L<X509_STORE_set_default_paths(3)>.

Functions return number of objects loaded from file or 0 in case of

error.

Both methods support adding several certificate locations into one

B<X509_STORE>.

This page documents certificate store formats used by these methods and

caching policy.

=head2 File Method

The B<X509_LOOKUP_file> method loads all the certificates or CRLs

present in a file into memory at the time the file is added as a

lookup source.

File format is ASCII text which contains concatenated PEM certificates

and CRLs.

This method should be used by applications which work with a small

set of CAs.

=head2 Hashed Directory Method

B<X509_LOOKUP_hash_dir> is a more advanced method, which loads

certificates and CRLs on demand, and caches them in memory once

they are loaded. As of OpenSSL 1.0.0, it also checks for newer CRLs

upon each lookup, so that newer CRLs are as soon as they appear in

the directory.

The directory should contain one certificate or CRL per file in PEM format,

with a file name of the form I<hash>.I<N> for a certificate, or

I<hash>.B<r>I<N> for a CRL.

The I<hash> is the value returned by the L<X509_NAME_hash(3)> function applied

to the subject name for certificates or issuer name for CRLs.

The hash can also be obtained via the B<-hash> option of the L<x509(1)> or

L<crl(1)> commands.

The .I<N> or .B<r>I<N> suffix is a sequence number that starts at zero, and is

incremented consecutively for each certificate or CRL with the same I<hash>

value.

Gaps in the sequence numbers are not supported, it is assumed that there are no

more objects with the same hash beyond the first missing number in the

sequence.

Sequence numbers make it possible for the directory to contain multiple

certificates with same subject name hash value.

For example, it is possible to have in the store several certificates with same

subject or several CRLs with same issuer (and, for example, different validity

period).

When checking for new CRLs once one CRL for given hash value is

loaded, hash_dir lookup method checks only for certificates with

sequence number greater than that of the already cached CRL.

Note that the hash algorithm used for subject name hashing changed in OpenSSL

1.0.0, and all certificate stores have to be rehashed when moving from OpenSSL

0.9.8 to 1.0.0.

OpenSSL includes a L<rehash(1)> utility which creates symlinks with correct

hashed names for all files with .pem suffix in a given directory.

=head1 RETURN VALUES

X509_LOOKUP_hash_dir() and X509_LOOKUP_file() always return a valid

B<X509_LOOKUP_METHOD> structure.

X509_load_cert_file(), X509_load_crl_file() and X509_load_cert_crl_file() return

the number of loaded objects or 0 on error.

=head1 SEE ALSO

L<PEM_read_PrivateKey(3)>,

L<X509_STORE_load_locations(3)>,

L<X509_store_add_lookup(3)>,

L<SSL_CTX_load_verify_locations(3)>,

L<X509_LOOKUP_meth_new(3)>,

=head1 COPYRIGHT

Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License").  You may not use

this file except in compliance with the License.  You can obtain a copy

in the file LICENSE in the source distribution or at

L<https://www.openssl.org/source/license.html>.

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