EVP\_MD-BLAKE2(7ossl) OpenSSL EVP\_MD-BLAKE2(7ossl)

# [NAME](#NAME)

EVP\_MD-BLAKE2 - The BLAKE2 EVP\_MD implementation

# [DESCRIPTION](#DESCRIPTION)

Support for computing BLAKE2 digests through the **EVP\_MD** API.

## [Identities](#Identities)

This implementation is only available with the default provider, and includes the following varieties:

[BLAKE2S-256](#BLAKE2S)

Known names are "BLAKE2S-256" and "BLAKE2s256".

[BLAKE2B-512](#BLAKE2B)

Known names are "BLAKE2B-512" and "BLAKE2b512".

## [Settable Parameters](#Settable_Parameters)

"BLAKE2B-512" supports the following **EVP\_MD\_CTX\_set\_params()** key described in "PARAMETERS" in [**EVP\_DigestInit**(3)](/man/os/openssl-4.0/EVP_DigestInit.3).

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

## [Gettable Parameters](#Gettable_Parameters)

This implementation supports the common gettable parameters described in [**EVP\_MD-common**(7)](/man/os/openssl-4.0/EVP_MD-common.7).

## [Settable Context Parameters](#Settable_Context_Parameters)

The implementation supports the following [**OSSL\_PARAM**(3)](/man/os/openssl-4.0/OSSL_PARAM.3) entries which are settable for an **EVP\_MD\_CTX** with [**EVP\_DigestInit\_ex2**(3)](/man/os/openssl-4.0/EVP_DigestInit_ex2.3) or [**EVP\_MD\_CTX\_set\_params**(3)](/man/os/openssl-4.0/EVP_MD_CTX_set_params.3):

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

Sets a different digest length for the [**EVP\_DigestFinal**(3)](/man/os/openssl-4.0/EVP_DigestFinal.3) output. The value of the "size" parameter must not exceed the default digest length of the respective BLAKE2 algorithm variants, 64 for BLAKE2B-512 and 32 for BLAKE2S-256. The parameter must be set with the [**EVP\_DigestInit\_ex2**(3)](/man/os/openssl-4.0/EVP_DigestInit_ex2.3) call to have an immediate effect. When set with [**EVP\_MD\_CTX\_set\_params**(3)](/man/os/openssl-4.0/EVP_MD_CTX_set_params.3) it will have an effect only if the **EVP\_MD\_CTX** context is reinitialized.

# [SEE ALSO](#SEE_ALSO)

[**provider-digest**(7)](/man/os/openssl-4.0/provider-digest.7), [**OSSL\_PROVIDER-default**(7)](/man/os/openssl-4.0/OSSL_PROVIDER-default.7)

# [HISTORY](#HISTORY)

This functionality was added in OpenSSL 3.0.

The variable size support was added in OpenSSL 3.2 for BLAKE2B-512 and in OpenSSL 3.3 for BLAKE2S-256.

# [COPYRIGHT](#COPYRIGHT)

Copyright 2020-2024 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 4.0.3

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Document: EVP_MD-BLAKE2(7ossl) from openssl-4.0 4.0.3-r6 (Chainguard OS)