EVP_MAC-GMAC(7ossl) OpenSSL EVP_MAC-GMAC(7ossl)
NAME
EVP_MAC-GMAC - The GMAC EVP_MAC implementation
DESCRIPTION
Support for computing GMAC MACs through the EVP_MAC API.
This implementation uses EVP_CIPHER functions to get access to the
underlying cipher.
Identity
This implementation is identified with this name and properties, to be
used with EVP_MAC_fetch():
"GMAC", "provider=default" or "provider=fips"
Supported parameters
The general description of these parameters can be found in "PARAMETERS"
in EVP_MAC(3).
The following parameter can be set with EVP_MAC_CTX_set_params():
"key" (OSSL_MAC_PARAM_KEY) <octet string>
Sets the MAC key. Setting this parameter is identical to passing a
key to EVP_MAC_init(3).
"iv" (OSSL_MAC_PARAM_IV) <octet string>
Sets the IV of the underlying cipher, when applicable.
"cipher" (OSSL_MAC_PARAM_CIPHER) <UTF8 string>
Sets the name of the underlying cipher to be used.
"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.
The following parameters can be retrieved with EVP_MAC_CTX_get_params():
"size" (OSSL_MAC_PARAM_SIZE) <unsigned integer>
Gets the MAC size.
"fips-indicator" (OSSL_MAC_PARAM_FIPS_APPROVED_INDICATOR) <integer>
The OpenSSL FIPS provider returns 1 if the operation is FIPS
approved, or 0 otherwise. See "FIPS indicators" in fips_module(7)
for more information.
The "size" parameter can also be retrieved with
EVP_MAC_CTX_get_mac_size(). The length of the "size" parameter is equal
to that of an unsigned int.
SEE ALSO
EVP_MAC_CTX_get_params(3), EVP_MAC_CTX_set_params(3), "PARAMETERS" in
EVP_MAC(3), OSSL_PARAM(3)
COPYRIGHT
Copyright 2018-2026 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>.
3.6.5 2026-09-29 EVP_MAC-GMAC(7ossl)
openssl 3.6.5 - Generated Sat Oct 3 09:30:54 CDT 2026