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
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);
are two certificate
lookup methods to use with 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
(3) or SSL_CTX_load_verify_locations
Internally loading of certificates and CRLs is implemented via functions
. These functions support parameter type
which can be one of constants FILETYPE_PEM
. They load certificates and/or CRLs from specified
file into memory cache of X509_STORE
objects which given ctx
parameter is associated with.
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) X509_load_cert_crl_file
is equivalent to X509_load_cert_file
with NULL filename causes these functions to
load default certificate store file (see
Functions return number of objects loaded from file or 0 in case of error.
Both methods support adding several certificate locations into one
This page documents certificate store formats used by these methods and caching
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.
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 hash
for a certificate, or
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
option of the x509
(1) or crl
The . N
suffix is a sequence number that starts at
zero, and is incremented consecutively for each certificate or CRL with the
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 rehash
(1) utility which creates symlinks with correct
hashed names for all files with .pem suffix in a given directory.
always return a
return the number of loaded objects or 0 on
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