Manual Reference Pages - X509_LOAD_CERT_CRL_FILE (3)
X509_load_cert_crl_file - Default OpenSSL certificate
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);
X509_LOOKUP_hash_dir and X509_LOOKUP_file 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
Internally loading of certificates and CRLs is implemented via functions
X509_load_cert_crl_file, X509_load_cert_file and
X509_load_crl_file. These functions support parameter type, which
can be one of constants FILETYPE_PEM, FILETYPE_ASN1 and
FILETYPE_DEFAULT. They load certificates and/or CRLs from specified
file into memory cache of X509_STORE objects which given ctx
parameter is associated with.
Functions X509_load_cert_file and
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)
X509_load_cert_crl_file with FILETYPE_ASN1 is equivalent to
Constant FILETYPE_DEFAULT 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
Both methods support adding several certificate locations into one
This page documents certificate store formats used by these methods and
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
File format is ASCII text which contains concatenated PEM certificates
This method should be used by applications which work with a small
set of CAs.
HASHED DIR 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 as soon as they appear in
The directory should contain one certificate or CRL per file in PEM format,
with a file name 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 x509(1) or
The .N or .rN suffix is a sequence number that starts at zero, and is
incremented consecutively for each certificate or CRL with the same hash
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 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
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 c_rehash(1) utility which creates symlinks with correct
hashed names for all files with .pem suffix in a given directory.
|1.1.0-pre3 ||X509_LOOKUP_HASH_DIR (3) ||2016-02-15 |
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