=pod

=head1 NAME

OSSL_CRMF_pbm_new,
OSSL_CRMF_pbmp_new
- functions for producing Password-Based MAC (PBM)

=head1 SYNOPSIS

  #include <openssl/crmf.h>

  int OSSL_CRMF_pbm_new(const OSSL_CRMF_PBMPARAMETER *pbmp,
                        const unsigned char *msg, size_t msglen,
                        const unsigned char *sec, size_t seclen,
                        unsigned char **mac, size_t *maclen);

  OSSL_CRMF_PBMPARAMETER *OSSL_CRMF_pbmp_new(size_t saltlen, int owfnid,
                                             int itercnt, int macnid);

=head1 DESCRIPTION

OSSL_CRMF_pbm_new() generates a PBM (Password-Based MAC) based on given PBM
parameters B<pbmp>, message B<msg>, and secret B<sec>, along with the respective
lengths B<msglen> and B<seclen>. On success writes the adddress of the newly
allocated MAC via the B<mac> reference parameter and writes the length via the
B<maclen> reference parameter unless it its NULL.

The iteration count must be at least 100, as stipulated by RFC 4211, and is
limited to at most 100000 to avoid DoS through manipulated or otherwise
malformed input.

OSSL_CRMF_pbmp_new() initializes and returns a new PBMParameter
structure with a new random salt of given length B<saltlen>, OWF (one-way
function) NID B<owfnid>, iteration count B<itercnt>, and MAC NID B<macnid>.

=head1 NOTES

The algorithms for the OWF (one-way function) and for the MAC (message
authentication code) may be any with a NID defined in B<openssl/objects.h>.
As specified by RFC 4210, these should include NID_hmac_sha1.

RFC 4210 recommends that the salt SHOULD be at least 8 bytes (64 bits) long.

=head1 RETURN VALUES

OSSL_CRMF_pbm_new() returns 1 on success, 0 on error.

OSSL_CRMF_pbmp_new() returns a new and initialized OSSL_CRMF_PBMPARAMETER
structure, or NULL on error.

=head1 EXAMPLE

 OSSL_CRMF_PBMPARAMETER *pbm = NULL;
 unsigned char *msg = "Hello";
 unsigned char *sec = "SeCrEt";
 unsigned char *mac = NULL;
 size_t maclen;

 if ((pbm = OSSL_CRMF_pbmp_new(16, NID_sha256, 500, NID_hmac_sha1) == NULL))
     goto err;
 if (!OSSL_CRMF_pbm_new(pbm, msg, 5, sec, 6, &mac, &maclen))
     goto err;

=head1 SEE ALSO

RFC 4211 section 4.4

=head1 COPYRIGHT

Copyright 2007-2019 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
L<https://www.openssl.org/source/license.html>.

=cut
