# phpman > man > EVP_MAC-HMAC(7SSL)

[EVP_MAC-HMAC(7SSL)](https://www.chedong.com/phpMan.php/man/EVPMAC-HMAC/7SSL/markdown)                             OpenSSL                            [EVP_MAC-HMAC(7SSL)](https://www.chedong.com/phpMan.php/man/EVPMAC-HMAC/7SSL/markdown)



## NAME
       EVP_MAC-HMAC - The HMAC EVP_MAC implementation

## DESCRIPTION
       Support for computing HMAC MACs through the **EVP**___**MAC** API.

       This implementation uses EVP_MD functions to get access to the underlying digest.

### Identity
       This implementation is identified with this name and properties, to be used with
       **EVP**___**MAC**___**fetch()**:

       "HMAC", "provider=default" or "provider=fips"

### Supported parameters
       The general description of these parameters can be found in "PARAMETERS" in **EVP**___**[MAC**(3)](https://www.chedong.com/phpMan.php/man/MAC/3/markdown).

       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)](https://www.chedong.com/phpMan.php/man/init/3/markdown).

       "digest" (**OSSL**___**MAC**___**PARAM**___**DIGEST**) <UTF8 string>
           Sets the name of the underlying digest to be used.

       "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 **OSSL**___**MAC**___**PARAM**___**DIGEST**)
           to be considered valid.

       "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.

       "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.

       "tls-data-size" (**OSSL**___**MAC**___**PARAM**___**TLS**___**DATA**___**SIZE**) <unsigned integer>

       The following parameter can be retrieved with **EVP**___**MAC**___**CTX**___**get**___**params()**:

       "size" (**OSSL**___**MAC**___**PARAM**___**SIZE**) <unsigned integer>
           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**.

       "block-size" (**OSSL**___**MAC**___**PARAM**___**SIZE**) <unsigned integer>
           Gets the MAC block size.  The "block-size" parameter can also be retrieved with
           **EVP**___**MAC**___**CTX**___**get**___**block**___**size()**.

## SEE ALSO
       **EVP**___**MAC**___**CTX**___**get**___**[params**(3)](https://www.chedong.com/phpMan.php/man/params/3/markdown), **EVP**___**MAC**___**CTX**___**set**___**[params**(3)](https://www.chedong.com/phpMan.php/man/params/3/markdown), "PARAMETERS" in **EVP**___**[MAC**(3)](https://www.chedong.com/phpMan.php/man/MAC/3/markdown),
       **OSSL**___**[PARAM**(3)](https://www.chedong.com/phpMan.php/man/PARAM/3/markdown), [**HMAC**(3)](https://www.chedong.com/phpMan.php/man/HMAC/3/markdown)

## COPYRIGHT
       Copyright 2018-2021 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>>.



3.0.2                                        2026-06-02                           [EVP_MAC-HMAC(7SSL)](https://www.chedong.com/phpMan.php/man/EVPMAC-HMAC/7SSL/markdown)