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/* $OpenBSD: e_chacha.c,v 1.9 2022/07/30 17:11:38 jsing Exp $ */
/*
* Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
*
* Permission to use, copy, modify, and 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.
*/
#include <openssl/opensslconf.h>
#ifndef OPENSSL_NO_CHACHA
#include <openssl/chacha.h>
#include <openssl/evp.h>
#include <openssl/objects.h>
#include "evp_locl.h"
static int
chacha_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
const unsigned char *openssl_iv, int enc)
{
if (key != NULL)
ChaCha_set_key((ChaCha_ctx *)ctx->cipher_data, key,
EVP_CIPHER_CTX_key_length(ctx) * 8);
if (openssl_iv != NULL) {
const unsigned char *iv = openssl_iv + 8;
const unsigned char *counter = openssl_iv;
ChaCha_set_iv((ChaCha_ctx *)ctx->cipher_data, iv, counter);
}
return 1;
}
static int
chacha_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, const unsigned char *in,
size_t len)
{
ChaCha((ChaCha_ctx *)ctx->cipher_data, out, in, len);
return 1;
}
static const EVP_CIPHER chacha20_cipher = {
.nid = NID_chacha20,
.block_size = 1,
.key_len = 32,
/*
* The 128 bit EVP IV is split for ChaCha into four 32 bit pieces:
* counter[0] counter[1] iv[0] iv[1]
* OpenSSL exposes these as:
* openssl_iv = counter[0] iv[0] iv[1] iv[2]
* Due to the cipher internal state's symmetry, these are functionally
* equivalent.
*/
.iv_len = 16,
.flags = EVP_CIPH_STREAM_CIPHER | EVP_CIPH_ALWAYS_CALL_INIT |
EVP_CIPH_CUSTOM_IV,
.init = chacha_init,
.do_cipher = chacha_cipher,
.ctx_size = sizeof(ChaCha_ctx)
};
const EVP_CIPHER *
EVP_chacha20(void)
{
return (&chacha20_cipher);
}
#endif
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