NAME

       PKCS12_key_gen_asc, PKCS12_key_gen_asc_ex, PKCS12_key_gen_uni, PKCS12_key_gen_uni_ex,
       PKCS12_key_gen_utf8, PKCS12_key_gen_utf8_ex - PKCS#12 Password based key derivation

SYNOPSIS

        #include <openssl/pkcs12.h>

        int PKCS12_key_gen_asc(const char *pass, int passlen, unsigned char *salt,
                               int saltlen, int id, int iter, int n,
                               unsigned char *out, const EVP_MD *md_type);
        int PKCS12_key_gen_asc_ex(const char *pass, int passlen, unsigned char *salt,
                                  int saltlen, int id, int iter, int n,
                                  unsigned char *out, const EVP_MD *md_type,
                                  OSSL_LIB_CTX *ctx, const char *propq);
        int PKCS12_key_gen_uni(unsigned char *pass, int passlen, unsigned char *salt,
                               int saltlen, int id, int iter, int n,
                               unsigned char *out, const EVP_MD *md_type);
        int PKCS12_key_gen_uni_ex(unsigned char *pass, int passlen, unsigned char *salt,
                                  int saltlen, int id, int iter, int n,
                                  unsigned char *out, const EVP_MD *md_type,
                                  OSSL_LIB_CTX *ctx, const char *propq);
        int PKCS12_key_gen_utf8(const char *pass, int passlen, unsigned char *salt,
                                int saltlen, int id, int iter, int n,
                                unsigned char *out, const EVP_MD *md_type);
        int PKCS12_key_gen_utf8_ex(const char *pass, int passlen, unsigned char *salt,
                                   int saltlen, int id, int iter, int n,
                                   unsigned char *out, const EVP_MD *md_type,
                                   OSSL_LIB_CTX *ctx, const char *propq);

DESCRIPTION

       These methods perform a key derivation according to PKCS#12 (RFC7292) with an input
       password pass of length passlen, a salt salt of length saltlen, an iteration count iter
       and a digest algorithm md_type.  The ID byte id determines how the resulting key is
       intended to be used:

       •   If ID=1, then the pseudorandom bits being produced are to be used as key material for
           performing encryption or decryption.

       •   If ID=2, then the pseudorandom bits being produced are to be used as an IV (Initial
           Value) for encryption or decryption.

       •   If ID=3, then the pseudorandom bits being produced are to be used as an integrity key
           for MACing.

       The intended format of the supplied password is determined by the method chosen:

       •   PKCS12_key_gen_asc() and PKCS12_key_gen_asc_ex() expect an ASCII-formatted password.

       •   PKCS12_key_gen_uni() and PKCS12_key_gen_uni_ex() expect a Unicode-formatted password.

       •   PKCS12_key_gen_utf8() and PKCS12_key_gen_utf8_ex() expect a UTF-8 encoded password.

       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 less than 1 is treated as a single
       iteration.

       digest is the message digest function used in the derivation.

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

       Functions ending in _ex() allow for a library context ctx and property query propq to be
       used to select algorithm implementations.

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.

RETURN VALUES

       Returns 1 on success or 0 on error.

CONFORMING TO

       IETF RFC 7292 (<https://tools.ietf.org/html/rfc7292>)

SEE ALSO

       PKCS12_create_ex(3), PKCS12_pbe_crypt_ex(3), passphrase-encoding(7)

HISTORY

       PKCS12_key_gen_asc_ex(), PKCS12_key_gen_uni_ex() and PKCS12_key_gen_utf8_ex() were added
       in OpenSSL 3.0.

COPYRIGHT

       Copyright 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>.