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Command: X509_LOOKUP_hash_dir | Section: 3 | Source: OpenBSD | File: X509_LOOKUP_hash_dir.3
X509_LOOKUP_HASH_DIR(3) FreeBSD Library Functions Manual
NAME
X509_LOOKUP_hash_dir, X509_LOOKUP_file, X509_LOOKUP_mem - certificate
lookup methods
SYNOPSIS
#include <openssl/x509_vfy.h>
const X509_LOOKUP_METHOD *
X509_LOOKUP_hash_dir(void);
const X509_LOOKUP_METHOD *
X509_LOOKUP_file(void);
const X509_LOOKUP_METHOD *
X509_LOOKUP_mem(void);
DESCRIPTION
X509_LOOKUP_hash_dir(), X509_LOOKUP_file(), and X509_LOOKUP_mem() return
pointers to static certificate lookup method objects built into the
library, for use with X509_STORE.
Users of the library typically do not need to retrieve pointers to these
method objects manually. They are automatically used by the
X509_STORE_load_locations(3) or SSL_CTX_load_verify_locations(3)
functions.
File Method
The 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.
The 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.
Hashed Directory Method
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.
The directory should contain one certificate or CRL per file in PEM
format, with a filename of the form hash.N for a certificate, or hash.rN
for a CRL. The hash is the value returned by the 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 -hash option of the
openssl(1) x509 or crl commands.
The N suffix is a sequence number that starts at zero and is incremented
consecutively for each certificate or CRL with the same 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 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).
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.
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.
Memory Method
The X509_LOOKUP_mem() method supports loading PEM-encoded certificates
and revocation lists that are already stored in memory, using the
function X509_LOOKUP_add_mem(3). This is particularly useful in
processes using chroot(2).
RETURN VALUES
These functions always return a pointer to a static object.
SEE ALSO
SSL_CTX_load_verify_locations(3), X509_LOOKUP_new(3),
X509_STORE_load_locations(3), X509_STORE_new(3)
HISTORY
X509_LOOKUP_hash_dir() and X509_LOOKUP_file() first appeared in SSLeay
0.8.0 and have been available since OpenBSD 2.4.
X509_LOOKUP_mem() first appeared in OpenBSD 5.7.
FreeBSD 14.1-RELEASE-p8 September 2, 2024 FreeBSD 14.1-RELEASE-p8