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.IX Title "EVP_MD-BLAKE2 7ossl"
.TH EVP_MD-BLAKE2 7ossl 2026-06-09 3.5.7 OpenSSL
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.SH NAME
EVP_MD\-BLAKE2 \- The BLAKE2 EVP_MD implementation
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Support for computing BLAKE2 digests through the \fBEVP_MD\fR API.
.SS Identities
.IX Subsection "Identities"
This implementation is only available with the default provider, and
includes the following varieties:
.IP BLAKE2S\-256 4
.IX Item "BLAKE2S-256"
Known names are "BLAKE2S\-256" and "BLAKE2s256".
.IP BLAKE2B\-512 4
.IX Item "BLAKE2B-512"
Known names are "BLAKE2B\-512" and "BLAKE2b512".
.SS "Settable Parameters"
.IX Subsection "Settable Parameters"
"BLAKE2B\-512" supports the following \fBEVP_MD_CTX_set_params()\fR key
described in "PARAMETERS" in \fBEVP_DigestInit\fR\|(3).
.IP """size"" (\fBOSSL_DIGEST_PARAM_SIZE\fR) <unsigned integer>" 4
.IX Item """size"" (OSSL_DIGEST_PARAM_SIZE) <unsigned integer>"
.SS "Gettable Parameters"
.IX Subsection "Gettable Parameters"
This implementation supports the common gettable parameters described
in \fBEVP_MD\-common\fR\|(7).
.SS "Settable Context Parameters"
.IX Subsection "Settable Context Parameters"
The implementation supports the following \fBOSSL_PARAM\fR\|(3) entries which
are settable for an \fBEVP_MD_CTX\fR with \fBEVP_DigestInit_ex2\fR\|(3) or
\&\fBEVP_MD_CTX_set_params\fR\|(3):
.IP """size"" (\fBOSSL_DIGEST_PARAM_SIZE\fR) <unsigned integer>" 4
.IX Item """size"" (OSSL_DIGEST_PARAM_SIZE) <unsigned integer>"
Sets a different digest length for the \fBEVP_DigestFinal\fR\|(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
\&\fBEVP_DigestInit_ex2\fR\|(3) call to have an immediate effect. When set with
\&\fBEVP_MD_CTX_set_params\fR\|(3) it will have an effect only if the \fBEVP_MD_CTX\fR
context is reinitialized.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBprovider\-digest\fR\|(7), \fBOSSL_PROVIDER\-default\fR\|(7)
.SH HISTORY
.IX Header "HISTORY"
This functionality was added in OpenSSL 3.0.
.PP
The variable size support was added in OpenSSL 3.2 for BLAKE2B\-512 and
in OpenSSL 3.3 for BLAKE2S\-256.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2020\-2024 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>.
