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EVP_MAC-Poly1305.7ossl - Man Page

The Poly1305 EVP_MAC implementation


Support for computing Poly1305 MACs through the EVP_MAC API.


This implementation is identified with this name and properties, to be used with EVP_MAC_fetch():

"POLY1305", "provider=default"

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).

The following parameters can be retrieved with EVP_MAC_CTX_get_params():

"size" (OSSL_MAC_PARAM_SIZE) <unsigned integer>

Gets the MAC size.

The "size" parameter can also be retrieved with with EVP_MAC_CTX_get_mac_size(). The length of the "size" parameter should not exceed that of an unsigned int.


The OpenSSL implementation of the Poly 1305 MAC corresponds to RFC 7539.

It is critical to never reuse the key.  The security implication noted in RFC 8439 applies equally to the OpenSSL implementation.

See Also

EVP_MAC_CTX_get_params(3), EVP_MAC_CTX_set_params(3), "PARAMETERS" in EVP_MAC(3), OSSL_PARAM(3)

Referenced By

EVP_MAC.3ossl(3), EVP_SIGNATURE-HMAC.7ossl(7), openssl-mac.1ossl(1), ossl-guide-migration.7ossl(7), OSSL_PROVIDER-default.7ossl(7), provider-mac.7ossl(7).

2024-04-04 3.2.1 OpenSSL