forked from wolfSSL/wolfssl
255 lines
6.4 KiB
C
255 lines
6.4 KiB
C
/* chacha.c
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*
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* Copyright (C) 2006-2016 wolfSSL Inc.
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*
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* This file is part of wolfSSL.
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*
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* wolfSSL is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* wolfSSL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
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*
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* based from
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* chacha-ref.c version 20080118
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* D. J. Bernstein
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* Public domain.
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <wolfssl/wolfcrypt/settings.h>
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#ifdef HAVE_CHACHA
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#include <wolfssl/wolfcrypt/chacha.h>
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#include <wolfssl/wolfcrypt/error-crypt.h>
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#include <wolfssl/wolfcrypt/logging.h>
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#ifdef NO_INLINE
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#include <wolfssl/wolfcrypt/misc.h>
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#else
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#define WOLFSSL_MISC_INCLUDED
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#include <wolfcrypt/src/misc.c>
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#endif
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#ifdef CHACHA_AEAD_TEST
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#include <stdio.h>
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#endif
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#ifdef BIG_ENDIAN_ORDER
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#define LITTLE32(x) ByteReverseWord32(x)
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#else
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#define LITTLE32(x) (x)
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#endif
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/* Number of rounds */
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#define ROUNDS 20
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#define U32C(v) (v##U)
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#define U32V(v) ((word32)(v) & U32C(0xFFFFFFFF))
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#define U8TO32_LITTLE(p) LITTLE32(((word32*)(p))[0])
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#define ROTATE(v,c) rotlFixed(v, c)
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#define XOR(v,w) ((v) ^ (w))
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#define PLUS(v,w) (U32V((v) + (w)))
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#define PLUSONE(v) (PLUS((v),1))
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#define QUARTERROUND(a,b,c,d) \
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x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]),16); \
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x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]),12); \
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x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]), 8); \
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x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]), 7);
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/**
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* Set up iv(nonce). Earlier versions used 64 bits instead of 96, this version
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* uses the typical AEAD 96 bit nonce and can do record sizes of 256 GB.
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*/
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int wc_Chacha_SetIV(ChaCha* ctx, const byte* inIv, word32 counter)
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{
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word32 temp[CHACHA_IV_WORDS];/* used for alignment of memory */
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#ifdef CHACHA_AEAD_TEST
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word32 i;
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printf("NONCE : ");
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for (i = 0; i < CHACHA_IV_BYTES; i++) {
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printf("%02x", inIv[i]);
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}
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printf("\n\n");
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#endif
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if (ctx == NULL)
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return BAD_FUNC_ARG;
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XMEMCPY(temp, inIv, CHACHA_IV_BYTES);
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ctx->X[CHACHA_IV_BYTES+0] = counter; /* block counter */
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ctx->X[CHACHA_IV_BYTES+1] = LITTLE32(temp[0]); /* fixed variable from nonce */
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ctx->X[CHACHA_IV_BYTES+2] = LITTLE32(temp[1]); /* counter from nonce */
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ctx->X[CHACHA_IV_BYTES+3] = LITTLE32(temp[2]); /* counter from nonce */
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return 0;
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}
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/* "expand 32-byte k" as unsigned 32 byte */
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static const word32 sigma[4] = {0x61707865, 0x3320646e, 0x79622d32, 0x6b206574};
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/* "expand 16-byte k" as unsigned 16 byte */
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static const word32 tau[4] = {0x61707865, 0x3120646e, 0x79622d36, 0x6b206574};
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/**
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* Key setup. 8 word iv (nonce)
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*/
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int wc_Chacha_SetKey(ChaCha* ctx, const byte* key, word32 keySz)
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{
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const word32* constants;
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const byte* k;
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#ifdef XSTREAM_ALIGN
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word32 alignKey[8];
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#endif
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if (ctx == NULL)
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return BAD_FUNC_ARG;
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if (keySz != 16 && keySz != 32)
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return BAD_FUNC_ARG;
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#ifdef XSTREAM_ALIGN
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if ((wolfssl_word)key % 4) {
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WOLFSSL_MSG("wc_ChachaSetKey unaligned key");
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XMEMCPY(alignKey, key, keySz);
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k = (byte*)alignKey;
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}
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else {
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k = key;
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}
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#else
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k = key;
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#endif /* XSTREAM_ALIGN */
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#ifdef CHACHA_AEAD_TEST
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word32 i;
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printf("ChaCha key used :\n");
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for (i = 0; i < keySz; i++) {
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printf("%02x", key[i]);
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if ((i + 1) % 8 == 0)
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printf("\n");
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}
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printf("\n\n");
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#endif
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ctx->X[4] = U8TO32_LITTLE(k + 0);
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ctx->X[5] = U8TO32_LITTLE(k + 4);
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ctx->X[6] = U8TO32_LITTLE(k + 8);
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ctx->X[7] = U8TO32_LITTLE(k + 12);
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if (keySz == 32) {
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k += 16;
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constants = sigma;
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}
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else {
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constants = tau;
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}
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ctx->X[ 8] = U8TO32_LITTLE(k + 0);
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ctx->X[ 9] = U8TO32_LITTLE(k + 4);
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ctx->X[10] = U8TO32_LITTLE(k + 8);
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ctx->X[11] = U8TO32_LITTLE(k + 12);
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ctx->X[ 0] = constants[0];
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ctx->X[ 1] = constants[1];
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ctx->X[ 2] = constants[2];
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ctx->X[ 3] = constants[3];
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return 0;
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}
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/**
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* Converts word into bytes with rotations having been done.
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*/
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static INLINE void wc_Chacha_wordtobyte(word32 output[CHACHA_CHUNK_WORDS],
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const word32 input[CHACHA_CHUNK_WORDS])
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{
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word32 x[CHACHA_CHUNK_WORDS];
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word32 i;
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for (i = 0; i < CHACHA_CHUNK_WORDS; i++) {
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x[i] = input[i];
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}
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for (i = (ROUNDS); i > 0; i -= 2) {
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QUARTERROUND(0, 4, 8, 12)
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QUARTERROUND(1, 5, 9, 13)
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QUARTERROUND(2, 6, 10, 14)
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QUARTERROUND(3, 7, 11, 15)
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QUARTERROUND(0, 5, 10, 15)
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QUARTERROUND(1, 6, 11, 12)
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QUARTERROUND(2, 7, 8, 13)
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QUARTERROUND(3, 4, 9, 14)
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}
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for (i = 0; i < CHACHA_CHUNK_WORDS; i++) {
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x[i] = PLUS(x[i], input[i]);
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}
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for (i = 0; i < CHACHA_CHUNK_WORDS; i++) {
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output[i] = LITTLE32(x[i]);
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}
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}
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/**
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* Encrypt a stream of bytes
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*/
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static void wc_Chacha_encrypt_bytes(ChaCha* ctx, const byte* m, byte* c,
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word32 bytes)
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{
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byte* output;
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word32 temp[CHACHA_CHUNK_WORDS]; /* used to make sure aligned */
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word32 i;
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output = (byte*)temp;
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if (!bytes) return;
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for (;;) {
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wc_Chacha_wordtobyte(temp, ctx->X);
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ctx->X[CHACHA_IV_BYTES] = PLUSONE(ctx->X[CHACHA_IV_BYTES]);
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if (bytes <= CHACHA_CHUNK_BYTES) {
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for (i = 0; i < bytes; ++i) {
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c[i] = m[i] ^ output[i];
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}
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return;
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}
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for (i = 0; i < CHACHA_CHUNK_BYTES; ++i) {
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c[i] = m[i] ^ output[i];
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}
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bytes -= CHACHA_CHUNK_BYTES;
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c += CHACHA_CHUNK_BYTES;
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m += CHACHA_CHUNK_BYTES;
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}
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}
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/**
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* API to encrypt/decrypt a message of any size.
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*/
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int wc_Chacha_Process(ChaCha* ctx, byte* output, const byte* input, word32 msglen)
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{
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if (ctx == NULL)
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return BAD_FUNC_ARG;
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wc_Chacha_encrypt_bytes(ctx, input, output, msglen);
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return 0;
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}
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#endif /* HAVE_CHACHA*/
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