BLAKE2 is licensed to permit usage under the terms of the CC0, the OpenSSL License, or the Apache Public License 2.0 at the user's option. The license grant is reproduced in full below. /* BLAKE2 reference source code package - reference C implementations Copyright 2012, Samuel Neves . You may use this under the terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at your option. The terms of these licenses can be found at: - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0 - OpenSSL license : https://www.openssl.org/source/license.html - Apache 2.0 : http://www.apache.org/licenses/LICENSE-2.0 More information about the BLAKE2 hash function can be found at https://blake2.net. */