This project contains code developed by Daniel J. Bernstein which was
released into the public domain. This code is based on Bernstein's
"chacha-merged.c version 20080118". Daniel J. Bernstein's original code
can be found at the following here: http://cr.yp.to/chacha.html

This project also contains code based on part of the libsodium cryptographic
library. The xchacha_hchacha and xchacha_set_counter functions were borrowed 
from libsodium and modified.
More information about libsodium can be found at the following
websites:
https://github.com/jedisct1/libsodium
https://download.libsodium.org/doc/

The code based on libsodium is used under the following license:

/*
 * ISC License
 *
 * Copyright (c) 2013-2019
 * Frank Denis <j at pureftpd dot org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */