=pod

=head1 NAME

EVP_MD-BLAKE2 - The BLAKE2 EVP_MD implementation

=head1 DESCRIPTION

Support for computing BLAKE2 digests through the B<EVP_MD> API.

=head2 Identities

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

=over 4

=item BLAKE2S-256

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

=item BLAKE2B-512

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

=back

=head2 Settable Parameters

"BLAKE2B-512" supports the following EVP_MD_CTX_set_params() key
described in L<EVP_DigestInit(3)/PARAMETERS>.

=over 4

=item "size" (B<OSSL_DIGEST_PARAM_SIZE>) <unsigned integer>

=back

=head2 Gettable Parameters

This implementation supports the common gettable parameters described
in L<EVP_MD-common(7)>.

=head2 Settable Context Parameters

The implementation supports the following L<OSSL_PARAM(3)> entries which
are settable for an B<EVP_MD_CTX> with L<EVP_DigestInit_ex2(3)> or
L<EVP_MD_CTX_set_params(3)>:

=over 4

=item "size" (B<OSSL_DIGEST_PARAM_SIZE>) <unsigned integer>

Sets a different digest length for the L<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
L<EVP_DigestInit_ex2(3)> call to have an immediate effect. When set with
L<EVP_MD_CTX_set_params(3)> it will have an effect only if the B<EVP_MD_CTX>
context is reinitialized.

=back

=head1 SEE ALSO

L<provider-digest(7)>, L<OSSL_PROVIDER-default(7)>

=head1 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.

=head1 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
L<https://www.openssl.org/source/license.html>.

=cut