NAME

       PKCS5_PBKDF2_HMAC, PKCS5_PBKDF2_HMAC_SHA1 - password based derivation routines with salt and iteration
       count

SYNOPSIS

        #include <openssl/evp.h>

        int PKCS5_PBKDF2_HMAC(const char *pass, int passlen,
                              const unsigned char *salt, int saltlen, int iter,
                              const EVP_MD *digest,
                              int keylen, unsigned char *out);

        int PKCS5_PBKDF2_HMAC_SHA1(const char *pass, int passlen,
                                   const unsigned char *salt, int saltlen, int iter,
                                   int keylen, unsigned char *out);

DESCRIPTION

       PKCS5_PBKDF2_HMAC() derives a key from a password using a salt and iteration count as specified in RFC
       2898.

       pass is the password used in the derivation of length passlen. pass is an optional parameter and can be
       NULL. If passlen is -1, then the function will calculate the length of pass using strlen().

       salt is the salt used in the derivation of length saltlen. If the salt is NULL, then saltlen must be 0.
       The function will not attempt to calculate the length of the salt because it is not assumed to be NULL
       terminated.

       iter is the iteration count and its value should be greater than or equal to 1. RFC 2898 suggests an
       iteration count of at least 1000. Any iter value less than 1 is invalid; such values will result in
       failure and raise the PROV_R_INVALID_ITERATION_COUNT error.

       digest is the message digest function used in the derivation.  PKCS5_PBKDF2_HMAC_SHA1() calls
       PKCS5_PBKDF2_HMAC() with EVP_sha1().

       The derived key will be written to out. The size of the out buffer is specified via keylen.

NOTES

       A typical application of this function is to derive keying material for an encryption algorithm from a
       password in the pass, a salt in salt, and an iteration count.

       Increasing the iter parameter slows down the algorithm which makes it harder for an attacker to perform a
       brute force attack using a large number of candidate passwords.

       These functions make no assumption regarding the given password.  It will simply be treated as a byte
       sequence.

RETURN VALUES

       PKCS5_PBKDF2_HMAC() and PBKCS5_PBKDF2_HMAC_SHA1() return 1 on success or 0 on error.

SEE ALSO

       evp(7), RAND_bytes(3), EVP_BytesToKey(3), passphrase-encoding(7)

COPYRIGHT

       Copyright 2014-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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
       <https://www.openssl.org/source/license.html>.

3.4.1                                              2025-04-03                            PKCS5_PBKDF2_HMAC(3SSL)