.\" $OpenBSD: X509_LOOKUP_hash_dir.3,v 1.13 2024/09/02 07:20:21 tb Exp $ .\" full merge up to: OpenSSL 61f805c1 Jan 16 01:01:46 2018 +0800 .\" selective merge up to: OpenSSL 24a535ea Sep 22 13:14:20 2020 +0100 .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2021 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. 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IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: September 2 2024 $ .Dt X509_LOOKUP_HASH_DIR 3 .Os .Sh NAME .Nm X509_LOOKUP_hash_dir , .Nm X509_LOOKUP_file , .Nm X509_LOOKUP_mem .Nd certificate lookup methods .Sh SYNOPSIS .In openssl/x509_vfy.h .Ft const X509_LOOKUP_METHOD * .Fn X509_LOOKUP_hash_dir void .Ft const X509_LOOKUP_METHOD * .Fn X509_LOOKUP_file void .Ft const X509_LOOKUP_METHOD * .Fn X509_LOOKUP_mem void .Sh DESCRIPTION .Fn X509_LOOKUP_hash_dir , .Fn X509_LOOKUP_file , and .Fn X509_LOOKUP_mem return pointers to static certificate lookup method objects built into the library, for use with .Vt X509_STORE . .Pp Users of the library typically do not need to retrieve pointers to these method objects manually. They are automatically used by the .Xr X509_STORE_load_locations 3 or .Xr SSL_CTX_load_verify_locations 3 functions. .Ss File Method The .Fn 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. .Pp The file format is ASCII text which contains concatenated PEM certificates and CRLs. .Pp This method should be used by applications which work with a small set of CAs. .Ss Hashed Directory Method .Fa 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 used as soon as they appear in the directory. .Pp The directory should contain one certificate or CRL per file in PEM format, with a filename of the form .Ar hash . Ns Ar N for a certificate, or .Ar hash . Ns Sy r Ns Ar N for a CRL. The .Ar hash is the value returned by the .Xr 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 .Fl hash option of the .Xr openssl 1 .Cm x509 or .Cm crl commands. .Pp The .Ar N suffix is a sequence number that starts at zero and is incremented consecutively for each certificate or CRL with the same .Ar 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. .Pp Sequence numbers make it possible for the directory to contain multiple certificates with the same subject name hash value. For example, it is possible to have in the store several certificates with the same subject or several CRLs with the same issuer (and, for example, a different validity period). .Pp When checking for new CRLs, once one CRL for a given hash value is loaded, hash_dir lookup method checks only for certificates with sequence number greater than that of the already cached CRL. .Pp 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. .Ss Memory Method The .Fn X509_LOOKUP_mem method supports loading PEM-encoded certificates and revocation lists that are already stored in memory, using the function .Xr X509_LOOKUP_add_mem 3 . This is particularly useful in processes using .Xr chroot 2 . .Sh RETURN VALUES These functions always return a pointer to a static object. .Sh SEE ALSO .Xr SSL_CTX_load_verify_locations 3 , .Xr X509_LOOKUP_new 3 , .Xr X509_STORE_load_locations 3 , .Xr X509_STORE_new 3 .Sh HISTORY .Fn X509_LOOKUP_hash_dir and .Fn X509_LOOKUP_file first appeared in SSLeay 0.8.0 and have been available since .Ox 2.4 . .Pp .Fn X509_LOOKUP_mem first appeared in .Ox 5.7 .