mirror of https://github.com/openssl/openssl.git
165 lines
6.0 KiB
Plaintext
165 lines
6.0 KiB
Plaintext
=pod
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=head1 NAME
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X509_LOOKUP_hash_dir, X509_LOOKUP_file, X509_LOOKUP_store,
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X509_load_cert_file_ex, X509_load_cert_file,
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X509_load_crl_file,
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X509_load_cert_crl_file_ex, X509_load_cert_crl_file
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- Default OpenSSL certificate lookup methods
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=head1 SYNOPSIS
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#include <openssl/x509_vfy.h>
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X509_LOOKUP_METHOD *X509_LOOKUP_hash_dir(void);
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X509_LOOKUP_METHOD *X509_LOOKUP_file(void);
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X509_LOOKUP_METHOD *X509_LOOKUP_store(void);
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int X509_load_cert_file_ex(X509_LOOKUP *ctx, const char *file, int type,
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OSSL_LIB_CTX *libctx, const char *propq);
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int X509_load_cert_file(X509_LOOKUP *ctx, const char *file, int type);
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int X509_load_crl_file(X509_LOOKUP *ctx, const char *file, int type);
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int X509_load_cert_crl_file_ex(X509_LOOKUP *ctx, const char *file, int type,
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OSSL_LIB_CTX *libctx, const char *propq);
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int X509_load_cert_crl_file(X509_LOOKUP *ctx, const char *file, int type);
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=head1 DESCRIPTION
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B<X509_LOOKUP_hash_dir> and B<X509_LOOKUP_file> are two certificate
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lookup methods to use with B<X509_STORE>, provided by OpenSSL library.
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Users of the library typically do not need to create instances of these
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methods manually, they would be created automatically by
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L<X509_STORE_load_locations(3)> or
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L<SSL_CTX_load_verify_locations(3)>
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functions.
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Internally loading of certificates and CRLs is implemented via functions
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B<X509_load_cert_crl_file>, B<X509_load_cert_file> and
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B<X509_load_crl_file>. These functions support parameter I<type>, which
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can be one of constants B<FILETYPE_PEM>, B<FILETYPE_ASN1> and
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B<FILETYPE_DEFAULT>. They load certificates and/or CRLs from specified
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file into memory cache of B<X509_STORE> objects which given B<ctx>
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parameter is associated with.
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Functions B<X509_load_cert_file> and
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B<X509_load_crl_file> can load both PEM and DER formats depending of
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type value. Because DER format cannot contain more than one certificate
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or CRL object (while PEM can contain several concatenated PEM objects)
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B<X509_load_cert_crl_file> with B<FILETYPE_ASN1> is equivalent to
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B<X509_load_cert_file>.
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Constant B<FILETYPE_DEFAULT> with NULL filename causes these functions
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to load default certificate store file (see
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L<X509_STORE_set_default_paths(3)>.
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Functions return number of objects loaded from file or 0 in case of
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error.
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Both methods support adding several certificate locations into one
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B<X509_STORE>.
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This page documents certificate store formats used by these methods and
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caching policy.
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=head2 File Method
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The B<X509_LOOKUP_file> method loads all the certificates or CRLs
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present in a file into memory at the time the file is added as a
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lookup source.
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File format is ASCII text which contains concatenated PEM certificates
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and CRLs.
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This method should be used by applications which work with a small
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set of CAs.
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=head2 Hashed Directory Method
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B<X509_LOOKUP_hash_dir> is a more advanced method, which loads
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certificates and CRLs on demand, and caches them in memory once
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they are loaded. As of OpenSSL 1.0.0, it also checks for newer CRLs
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upon each lookup, so that newer CRLs are as soon as they appear in
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the directory.
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The directory should contain one certificate or CRL per file in PEM format,
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with a filename of the form I<hash>.I<N> for a certificate, or
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I<hash>.B<r>I<N> for a CRL.
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The I<hash> is the value returned by the L<X509_NAME_hash_ex(3)> function
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applied to the subject name for certificates or issuer name for CRLs.
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The hash can also be obtained via the B<-hash> option of the
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L<openssl-x509(1)> or L<openssl-crl(1)> commands.
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The .I<N> or .B<r>I<N> suffix is a sequence number that starts at zero, and is
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incremented consecutively for each certificate or CRL with the same I<hash>
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value.
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Gaps in the sequence numbers are not supported, it is assumed that there are no
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more objects with the same hash beyond the first missing number in the
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sequence.
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Sequence numbers make it possible for the directory to contain multiple
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certificates with same subject name hash value.
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For example, it is possible to have in the store several certificates with same
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subject or several CRLs with same issuer (and, for example, different validity
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period).
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When checking for new CRLs once one CRL for given hash value is
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loaded, hash_dir lookup method checks only for certificates with
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sequence number greater than that of the already cached CRL.
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Note that the hash algorithm used for subject name hashing changed in OpenSSL
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1.0.0, and all certificate stores have to be rehashed when moving from OpenSSL
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0.9.8 to 1.0.0.
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OpenSSL includes a L<openssl-rehash(1)> utility which creates symlinks with
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hashed names for all files with F<.pem> suffix in a given directory.
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=head2 OSSL_STORE Method
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B<X509_LOOKUP_store> is a method that allows access to any store of
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certificates and CRLs through any loader supported by
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L<ossl_store(7)>.
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It works with the help of URIs, which can be direct references to
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certificates or CRLs, but can also be references to catalogues of such
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objects (that behave like directories).
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This method overlaps the L</File Method> and L</Hashed Directory Method>
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because of the 'file:' scheme loader.
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It does no caching of its own, but can use a caching L<ossl_store(7)>
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loader, and therefore depends on the loader's capability.
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=head1 RETURN VALUES
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X509_LOOKUP_hash_dir(), X509_LOOKUP_file() and X509_LOOKUP_store()
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always return a valid B<X509_LOOKUP_METHOD> structure.
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X509_load_cert_file(), X509_load_crl_file() and X509_load_cert_crl_file() return
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the number of loaded objects or 0 on error.
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=head1 SEE ALSO
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L<PEM_read_PrivateKey(3)>,
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L<X509_STORE_load_locations(3)>,
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L<SSL_CTX_load_verify_locations(3)>,
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L<X509_LOOKUP_meth_new(3)>,
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L<ossl_store(7)>
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=head1 HISTORY
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The functions X509_load_cert_file_ex(),
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X509_load_cert_crl_file_ex() and X509_LOOKUP_store() were added in
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OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2015-2021 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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