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/* chacha.c
*
* Copyright (C) 2006-2020 wolfSSL Inc.
*
* This file is part of wolfSSL.
*
* wolfSSL is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* wolfSSL is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <wolfssl/wolfcrypt/settings.h>
#if defined(HAVE_CHACHA) && defined(HAVE_POLY1305)
#include <wolfssl/wolfcrypt/chacha20_poly1305.h>
#include <wolfssl/wolfcrypt/error-crypt.h>
#include <wolfssl/wolfcrypt/logging.h>
#ifdef NO_INLINE
#include <wolfssl/wolfcrypt/misc.h>
#else
#define WOLFSSL_MISC_INCLUDED
#include <wolfcrypt/src/misc.c>
#endif
#define CHACHA20_POLY1305_AEAD_INITIAL_COUNTER 0
int wc_ChaCha20Poly1305_Encrypt(
const byte inKey[CHACHA20_POLY1305_AEAD_KEYSIZE],
const byte inIV[CHACHA20_POLY1305_AEAD_IV_SIZE],
const byte* inAAD, const word32 inAADLen,
const byte* inPlaintext, const word32 inPlaintextLen,
byte* outCiphertext,
byte outAuthTag[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE])
{
int ret;
ChaChaPoly_Aead aead;
/* Validate function arguments */
if (!inKey || !inIV ||
!inPlaintext || !inPlaintextLen ||
!outCiphertext ||
!outAuthTag)
{
return BAD_FUNC_ARG;
}
ret = wc_ChaCha20Poly1305_Init(&aead, inKey, inIV,
CHACHA20_POLY1305_AEAD_ENCRYPT);
if (ret == 0)
ret = wc_ChaCha20Poly1305_UpdateAad(&aead, inAAD, inAADLen);
if (ret == 0)
ret = wc_ChaCha20Poly1305_UpdateData(&aead, inPlaintext, outCiphertext,
inPlaintextLen);
if (ret == 0)
ret = wc_ChaCha20Poly1305_Final(&aead, outAuthTag);
return ret;
}
int wc_ChaCha20Poly1305_Decrypt(
const byte inKey[CHACHA20_POLY1305_AEAD_KEYSIZE],
const byte inIV[CHACHA20_POLY1305_AEAD_IV_SIZE],
const byte* inAAD, const word32 inAADLen,
const byte* inCiphertext, const word32 inCiphertextLen,
const byte inAuthTag[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE],
byte* outPlaintext)
{
int ret;
ChaChaPoly_Aead aead;
byte calculatedAuthTag[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE];
/* Validate function arguments */
if (!inKey || !inIV ||
!inCiphertext || !inCiphertextLen ||
!inAuthTag ||
!outPlaintext)
{
return BAD_FUNC_ARG;
}
XMEMSET(calculatedAuthTag, 0, sizeof(calculatedAuthTag));
ret = wc_ChaCha20Poly1305_Init(&aead, inKey, inIV,
CHACHA20_POLY1305_AEAD_DECRYPT);
if (ret == 0)
ret = wc_ChaCha20Poly1305_UpdateAad(&aead, inAAD, inAADLen);
if (ret == 0)
ret = wc_ChaCha20Poly1305_UpdateData(&aead, inCiphertext, outPlaintext,
inCiphertextLen);
if (ret == 0)
ret = wc_ChaCha20Poly1305_Final(&aead, calculatedAuthTag);
if (ret == 0)
ret = wc_ChaCha20Poly1305_CheckTag(inAuthTag, calculatedAuthTag);
return ret;
}
int wc_ChaCha20Poly1305_CheckTag(
const byte authTag[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE],
const byte authTagChk[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE])
{
int ret = 0;
if (authTag == NULL || authTagChk == NULL) {
return BAD_FUNC_ARG;
}
if (ConstantCompare(authTag, authTagChk,
CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE) != 0) {
ret = MAC_CMP_FAILED_E;
}
return ret;
}
int wc_ChaCha20Poly1305_Init(ChaChaPoly_Aead* aead,
const byte inKey[CHACHA20_POLY1305_AEAD_KEYSIZE],
const byte inIV[CHACHA20_POLY1305_AEAD_IV_SIZE],
int isEncrypt)
{
int ret;
byte authKey[CHACHA20_POLY1305_AEAD_KEYSIZE];
/* check arguments */
if (aead == NULL || inKey == NULL || inIV == NULL) {
return BAD_FUNC_ARG;
}
/* setup aead context */
XMEMSET(aead, 0, sizeof(ChaChaPoly_Aead));
XMEMSET(authKey, 0, sizeof(authKey));
aead->isEncrypt = isEncrypt;
/* Initialize the ChaCha20 context (key and iv) */
ret = wc_Chacha_SetKey(&aead->chacha, inKey,
CHACHA20_POLY1305_AEAD_KEYSIZE);
if (ret == 0) {
ret = wc_Chacha_SetIV(&aead->chacha, inIV,
CHACHA20_POLY1305_AEAD_INITIAL_COUNTER);
}
/* Create the Poly1305 key */
if (ret == 0) {
ret = wc_Chacha_Process(&aead->chacha, authKey, authKey,
CHACHA20_POLY1305_AEAD_KEYSIZE);
}
/* Initialize Poly1305 context */
if (ret == 0) {
ret = wc_Poly1305SetKey(&aead->poly, authKey,
CHACHA20_POLY1305_AEAD_KEYSIZE);
}
/* advance counter by 1 after creating Poly1305 key */
if (ret == 0) {
ret = wc_Chacha_SetIV(&aead->chacha, inIV,
CHACHA20_POLY1305_AEAD_INITIAL_COUNTER + 1);
}
if (ret == 0) {
aead->state = CHACHA20_POLY1305_STATE_READY;
}
return ret;
}
/* optional additional authentication data */
int wc_ChaCha20Poly1305_UpdateAad(ChaChaPoly_Aead* aead,
const byte* inAAD, word32 inAADLen)
{
int ret = 0;
if (aead == NULL || (inAAD == NULL && inAADLen > 0)) {
return BAD_FUNC_ARG;
}
if (aead->state != CHACHA20_POLY1305_STATE_READY &&
aead->state != CHACHA20_POLY1305_STATE_AAD) {
return BAD_STATE_E;
}
if (inAAD && inAADLen > 0) {
ret = wc_Poly1305Update(&aead->poly, inAAD, inAADLen);
if (ret == 0) {
aead->aadLen += inAADLen;
aead->state = CHACHA20_POLY1305_STATE_AAD;
}
}
return ret;
}
/* inData and outData can be same pointer (inline) */
int wc_ChaCha20Poly1305_UpdateData(ChaChaPoly_Aead* aead,
const byte* inData, byte* outData, word32 dataLen)
{
int ret = 0;
if (aead == NULL || inData == NULL || outData == NULL) {
return BAD_FUNC_ARG;
}
if (aead->state != CHACHA20_POLY1305_STATE_READY &&
aead->state != CHACHA20_POLY1305_STATE_AAD &&
aead->state != CHACHA20_POLY1305_STATE_DATA) {
return BAD_STATE_E;
}
/* Pad the AAD */
if (aead->state == CHACHA20_POLY1305_STATE_AAD) {
ret = wc_Poly1305_Pad(&aead->poly, aead->aadLen);
}
/* advance state */
aead->state = CHACHA20_POLY1305_STATE_DATA;
/* Perform ChaCha20 encrypt/decrypt and Poly1305 auth calc */
if (ret == 0) {
if (aead->isEncrypt) {
ret = wc_Chacha_Process(&aead->chacha, outData, inData, dataLen);
if (ret == 0)
ret = wc_Poly1305Update(&aead->poly, outData, dataLen);
}
else {
ret = wc_Poly1305Update(&aead->poly, inData, dataLen);
if (ret == 0)
ret = wc_Chacha_Process(&aead->chacha, outData, inData, dataLen);
}
}
if (ret == 0) {
aead->dataLen += dataLen;
}
return ret;
}
int wc_ChaCha20Poly1305_Final(ChaChaPoly_Aead* aead,
byte outAuthTag[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE])
{
int ret = 0;
if (aead == NULL || outAuthTag == NULL) {
return BAD_FUNC_ARG;
}
if (aead->state != CHACHA20_POLY1305_STATE_AAD &&
aead->state != CHACHA20_POLY1305_STATE_DATA) {
return BAD_STATE_E;
}
/* Pad the AAD - Make sure it is done */
if (aead->state == CHACHA20_POLY1305_STATE_AAD) {
ret = wc_Poly1305_Pad(&aead->poly, aead->aadLen);
}
/* Pad the ciphertext to 16 bytes */
if (ret == 0) {
ret = wc_Poly1305_Pad(&aead->poly, aead->dataLen);
}
/* Add the aad length and plaintext/ciphertext length */
if (ret == 0) {
ret = wc_Poly1305_EncodeSizes(&aead->poly, aead->aadLen,
aead->dataLen);
}
/* Finalize the auth tag */
if (ret == 0) {
ret = wc_Poly1305Final(&aead->poly, outAuthTag);
}
/* reset and cleanup sensitive context */
ForceZero(aead, sizeof(ChaChaPoly_Aead));
return ret;
}
#endif /* HAVE_CHACHA && HAVE_POLY1305 */
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