=pod

=head1 NAME

EVP_MAC-CMAC - The CMAC EVP_MAC implementation

=head1 DESCRIPTION

Support for computing CMAC MACs through the B<EVP_MAC> API.

This implementation uses EVP_CIPHER functions to get access to the underlying
cipher.

=head2 Identity

This implementation is identified with this name and properties, to be
used with EVP_MAC_fetch():

=over 4

=item "CMAC", "provider=default" or "provider=fips"

=back

=head2 Supported parameters

The general description of these parameters can be found in
L<EVP_MAC(3)/PARAMETERS>.

The following parameter can be set with EVP_MAC_CTX_set_params():

=over 4

=item "key" (B<OSSL_MAC_PARAM_KEY>) <octet string>

Sets the MAC key.
Setting this parameter is identical to passing a I<key> to L<EVP_MAC_init(3)>.

=item "cipher" (B<OSSL_MAC_PARAM_CIPHER>) <UTF8 string>

Sets the name of the underlying cipher to be used. The mode of the cipher
must be CBC.

=item "properties" (B<OSSL_MAC_PARAM_PROPERTIES>) <UTF8 string>

Sets the properties to be queried when trying to fetch the underlying cipher.
This must be given together with the cipher naming parameter to be considered
valid.

=item "encrypt-check" (B<OSSL_CIPHER_PARAM_FIPS_ENCRYPT_CHECK>) <integer>

This option is used by the OpenSSL FIPS provider.
If required this parameter should be set before EVP_MAC_init()

The default value of 1 causes an error when a unapproved Triple-DES encryption
operation is triggered.
Setting this to 0 will ignore the error and set the approved
"fips-indicator" to 0.
This option breaks FIPS compliance if it causes the approved "fips-indicator"
to return 0.

=back

The following parameters can be retrieved with
EVP_MAC_CTX_get_params():

=over 4

=item "size" (B<OSSL_MAC_PARAM_SIZE>) <unsigned integer>

The "size" parameter can also be retrieved with with EVP_MAC_CTX_get_mac_size().
The length of the "size" parameter is equal to that of an B<unsigned int>.


=item "block-size" (B<OSSL_MAC_PARAM_BLOCK_SIZE>) <unsigned integer>

Gets the MAC block size.  The "block-size" parameter can also be retrieved with
EVP_MAC_CTX_get_block_size().

=item "fips-indicator" (B<OSSL_CIPHER_PARAM_FIPS_APPROVED_INDICATOR>) <integer>

This option is used by the OpenSSL FIPS provider.

A getter that returns 1 if the operation is FIPS approved, or 0 otherwise.
This may be used after calling EVP_MAC_final().
It may return 0 if the "encrypt-check" option is set to 0.

=back

=head1 SEE ALSO

L<EVP_MAC_CTX_get_params(3)>, L<EVP_MAC_CTX_set_params(3)>,
L<EVP_MAC(3)/PARAMETERS>, L<OSSL_PARAM(3)>

=head1 COPYRIGHT

Copyright 2018-2024 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
