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/* ====================================================================
 * Copyright (c) 2014 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 */

#ifndef HEADER_CHACHA_H
#define HEADER_CHACHA_H

#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

# ifdef OPENSSL_NO_CHACHA
#  error CHACHA is disabled.
# endif

/*
 * ChaCha20_ctr32 encrypts |len| bytes from |inp| with the given key and
 * nonce and writes the result to |out|, which may be equal to |inp|.
 * The |key| is not 32 bytes of verbatim key material though, but the
 * said material collected into 8 32-bit elements array in host byte
 * order. Same approach applies to nonce: the |counter| argument is
 * pointer to concatenated nonce and counter values collected into 4
 * 32-bit elements. This, passing crypto material collected into 32-bit
 * elements as opposite to passing verbatim byte vectors, is chosen for
 * efficiency in multi-call scenarios.
 */
void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
                    size_t len, const unsigned int key[8],
                    const unsigned int counter[4]);
/*
 * You can notice that there is no key setup procedure. Because it's
 * as trivial as collecting bytes into 32-bit elements, it's reckoned
 * that below macro is sufficient.
 */
#define CHACHA_U8TOU32(p)  ( \
                ((unsigned int)(p)[0])     | ((unsigned int)(p)[1]<<8) | \
                ((unsigned int)(p)[2]<<16) | ((unsigned int)(p)[3]<<24)  )

#define CHACHA_KEY_SIZE		32
#define CHACHA_CTR_SIZE		16
#define CHACHA_BLK_SIZE		64

#ifdef __cplusplus
}
#endif
#endif