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X509_LOOKUP_hash_dir(3)             OpenSSL            X509_LOOKUP_hash_dir(3)

       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

       libcrypto, -lcrypto

        #include <openssl/x509_vfy.h>

        X509_LOOKUP_METHOD *X509_LOOKUP_hash_dir(void);
        X509_LOOKUP_METHOD *X509_LOOKUP_file(void);

        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
       X509_STORE_load_locations(3) or SSL_CTX_load_verify_locations(3)

       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

       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 X509_load_cert_file.

       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
       caching policy.

   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.

       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 as soon as they appear in the

       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 openssl_x509(1) or openssl_crl(1) commands.

       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 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

       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

       X509_LOOKUP_hash_dir() and X509_LOOKUP_file() always return a valid
       X509_LOOKUP_METHOD structure.

       X509_load_cert_file(), X509_load_crl_file() and
       X509_load_cert_crl_file() return the number of loaded objects or 0 on

       PEM_read_PrivateKey(3), X509_STORE_load_locations(3),
       X509_store_add_lookup(3), SSL_CTX_load_verify_locations(3),

       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

1.1.1                             2018-09-17           X509_LOOKUP_hash_dir(3)