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.\"
.IX Title "EVP_MAC-HMAC 7ssl"
.TH EVP_MAC-HMAC 7ssl 2024-01-30 3.2.1 OpenSSL
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.SH NAME
EVP_MAC\-HMAC \- The HMAC EVP_MAC implementation
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Support for computing HMAC MACs through the \fBEVP_MAC\fR API.
.PP
This implementation uses EVP_MD functions to get access to the underlying
digest.
.SS Identity
.IX Subsection "Identity"
This implementation is identified with this name and properties, to be
used with \fBEVP_MAC_fetch()\fR:
.IP """HMAC"", ""provider=default"" or ""provider=fips""" 4
.IX Item """HMAC"", ""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 """digest"" (\fBOSSL_MAC_PARAM_DIGEST\fR) <UTF8 string>" 4
.IX Item """digest"" (OSSL_MAC_PARAM_DIGEST) <UTF8 string>"
Sets the name of the underlying digest to be used.
.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 digest.
This must be given together with the digest naming parameter ("digest", or
\&\fBOSSL_MAC_PARAM_DIGEST\fR) to be considered valid.
.IP """digest-noinit"" (\fBOSSL_MAC_PARAM_DIGEST_NOINIT\fR) <integer>" 4
.IX Item """digest-noinit"" (OSSL_MAC_PARAM_DIGEST_NOINIT) <integer>"
A flag to set the MAC digest to not initialise the implementation
specific data.
The value 0 or 1 is expected.
.IP """digest-oneshot"" (\fBOSSL_MAC_PARAM_DIGEST_ONESHOT\fR) <integer>" 4
.IX Item """digest-oneshot"" (OSSL_MAC_PARAM_DIGEST_ONESHOT) <integer>"
A flag to set the MAC digest to be a one-shot operation.
The value 0 or 1 is expected.
.IP """tls-data-size"" (\fBOSSL_MAC_PARAM_TLS_DATA_SIZE\fR) <unsigned integer>" 4
.IX Item """tls-data-size"" (OSSL_MAC_PARAM_TLS_DATA_SIZE) <unsigned integer>"
.PP
The following parameter 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 \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.
.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), \fBHMAC\fR\|(3)
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2018\-2023 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>.