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.IX Title "EVP_MAC-CMAC 7ossl"
.TH EVP_MAC-CMAC 7ossl 2026-06-09 3.5.7 OpenSSL
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.SH NAME
EVP_MAC\-CMAC \- The CMAC EVP_MAC implementation
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Support for computing CMAC MACs through the \fBEVP_MAC\fR API.
.PP
This implementation uses EVP_CIPHER functions to get access to the underlying
cipher.
.SS Identity
.IX Subsection "Identity"
This implementation is identified with this name and properties, to be
used with \fBEVP_MAC_fetch()\fR:
.IP """CMAC"", ""provider=default"" or ""provider=fips""" 4
.IX Item """CMAC"", ""provider=default"" or ""provider=fips"""
.SS "Supported parameters"
.IX Subsection "Supported parameters"
The general description of these parameters can be found in
"PARAMETERS" in \fBEVP_MAC\fR\|(3).
.PP
The following parameter can be set with \fBEVP_MAC_CTX_set_params()\fR:
.IP """key"" (\fBOSSL_MAC_PARAM_KEY\fR) <octet string>" 4
.IX Item """key"" (OSSL_MAC_PARAM_KEY) <octet string>"
Sets the MAC key.
Setting this parameter is identical to passing a \fIkey\fR to \fBEVP_MAC_init\fR\|(3).
.IP """cipher"" (\fBOSSL_MAC_PARAM_CIPHER\fR) <UTF8 string>" 4
.IX Item """cipher"" (OSSL_MAC_PARAM_CIPHER) <UTF8 string>"
Sets the name of the underlying cipher to be used. The mode of the cipher
must be CBC.
.IP """properties"" (\fBOSSL_MAC_PARAM_PROPERTIES\fR) <UTF8 string>" 4
.IX Item """properties"" (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.
.IP """encrypt\-check"" (\fBOSSL_CIPHER_PARAM_FIPS_ENCRYPT_CHECK\fR) <integer>" 4
.IX Item """encrypt-check"" (OSSL_CIPHER_PARAM_FIPS_ENCRYPT_CHECK) <integer>"
This option is used by the OpenSSL FIPS provider.
If required this parameter should be set before \fBEVP_MAC_init()\fR
.Sp
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.
.PP
The following parameters can be retrieved with
\&\fBEVP_MAC_CTX_get_params()\fR:
.IP """size"" (\fBOSSL_MAC_PARAM_SIZE\fR) <unsigned integer>" 4
.IX Item """size"" (OSSL_MAC_PARAM_SIZE) <unsigned integer>"
The "size" parameter can also be retrieved with with \fBEVP_MAC_CTX_get_mac_size()\fR.
The length of the "size" parameter is equal to that of an \fBunsigned int\fR.
.IP """block\-size"" (\fBOSSL_MAC_PARAM_BLOCK_SIZE\fR) <unsigned integer>" 4
.IX Item """block-size"" (OSSL_MAC_PARAM_BLOCK_SIZE) <unsigned integer>"
Gets the MAC block size.  The "block\-size" parameter can also be retrieved with
\&\fBEVP_MAC_CTX_get_block_size()\fR.
.IP """fips\-indicator"" (\fBOSSL_CIPHER_PARAM_FIPS_APPROVED_INDICATOR\fR) <integer>" 4
.IX Item """fips-indicator"" (OSSL_CIPHER_PARAM_FIPS_APPROVED_INDICATOR) <integer>"
This option is used by the OpenSSL FIPS provider.
.Sp
A getter that returns 1 if the operation is FIPS approved, or 0 otherwise.
This may be used after calling \fBEVP_MAC_final()\fR.
It may return 0 if the "encrypt\-check" option is set to 0.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBEVP_MAC_CTX_get_params\fR\|(3), \fBEVP_MAC_CTX_set_params\fR\|(3),
"PARAMETERS" in \fBEVP_MAC\fR\|(3), \fBOSSL_PARAM\fR\|(3)
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2018\-2024 The OpenSSL Project Authors. All Rights Reserved.
.PP
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>.
