EVP\_MAC-SIPHASH(7ossl) OpenSSL EVP\_MAC-SIPHASH(7ossl)

# [NAME](#NAME)

EVP\_MAC-Siphash - The Siphash EVP\_MAC implementation

# [DESCRIPTION](#DESCRIPTION)

Support for computing Siphash MACs through the **EVP\_MAC** API.

## [Identity](#Identity)

This implementation is identified with this name and properties, to be used with **EVP\_MAC\_fetch()**:

"SIPHASH", "provider=default"

## [Supported parameters](#Supported_parameters)

The general description of these parameters can be found in "PARAMETERS" in [**EVP\_MAC**(3)](/man/os/openssl/EVP_MAC.3).

All these parameters can be set with **EVP\_MAC\_CTX\_set\_params()**. Furthermore, the "size" parameter can be retrieved with **EVP\_MAC\_CTX\_get\_params()**, or with **EVP\_MAC\_CTX\_get\_mac\_size()**. The length of the "size" parameter should not exceed that of a **size\_t**.

"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)](/man/os/openssl/EVP_MAC_init.3).

"size" (**OSSL\_MAC\_PARAM\_SIZE**) <unsigned integer>

Sets the MAC size.

"c-rounds" (**OSSL\_MAC\_PARAM\_C\_ROUNDS**) <unsigned integer>

Specifies the number of rounds per message block. By default this is *2*.

"d-rounds" (**OSSL\_MAC\_PARAM\_D\_ROUNDS**) <unsigned integer>

Specifies the number of finalisation rounds. By default this is *4*.

# [SEE ALSO](#SEE_ALSO)

[**EVP\_MAC\_CTX\_get\_params**(3)](/man/os/openssl/EVP_MAC_CTX_get_params.3), [**EVP\_MAC\_CTX\_set\_params**(3)](/man/os/openssl/EVP_MAC_CTX_set_params.3), "PARAMETERS" in [**EVP\_MAC**(3)](/man/os/openssl/EVP_MAC.3), [**OSSL\_PARAM**(3)](/man/os/openssl/OSSL_PARAM.3)

# [COPYRIGHT](#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>.

2026-09-29 3.6.5

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Document: EVP_MAC-Siphash(7ossl) from openssl 3.6.5-r0 (Chainguard OS)
Source: https://github.com/openssl/openssl