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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif
#include <string.h>
#include <stdio.h>
#include "seccomon.h"
#include "secerr.h"
#include "blapit.h"
#include "poly1305.h"
#include "chacha20.h"
#include "chacha20poly1305.h"
/* Poly1305Do writes the Poly1305 authenticator of the given additional data
* and ciphertext to |out|. */
static void
Poly1305Do(unsigned char *out, const unsigned char *ad, unsigned int adLen,
const unsigned char *ciphertext, unsigned int ciphertextLen,
const unsigned char key[32])
{
poly1305_state state;
unsigned int j;
unsigned char lengthBytes[8];
static const unsigned char zeros[15];
unsigned int i;
Poly1305Init(&state, key);
Poly1305Update(&state, ad, adLen);
if (adLen % 16 > 0) {
Poly1305Update(&state, zeros, 16 - adLen % 16);
}
Poly1305Update(&state, ciphertext, ciphertextLen);
if (ciphertextLen % 16 > 0) {
Poly1305Update(&state, zeros, 16 - ciphertextLen % 16);
}
j = adLen;
for (i = 0; i < sizeof(lengthBytes); i++) {
lengthBytes[i] = j;
j >>= 8;
}
Poly1305Update(&state, lengthBytes, sizeof(lengthBytes));
j = ciphertextLen;
for (i = 0; i < sizeof(lengthBytes); i++) {
lengthBytes[i] = j;
j >>= 8;
}
Poly1305Update(&state, lengthBytes, sizeof(lengthBytes));
Poly1305Finish(&state, out);
}
SECStatus
ChaCha20Poly1305_InitContext(ChaCha20Poly1305Context *ctx,
const unsigned char *key, unsigned int keyLen,
unsigned int tagLen)
{
if (keyLen != 32) {
PORT_SetError(SEC_ERROR_BAD_KEY);
return SECFailure;
}
if (tagLen == 0 || tagLen > 16) {
PORT_SetError(SEC_ERROR_INPUT_LEN);
return SECFailure;
}
PORT_Memcpy(ctx->key, key, sizeof(ctx->key));
ctx->tagLen = tagLen;
return SECSuccess;
}
ChaCha20Poly1305Context *
ChaCha20Poly1305_CreateContext(const unsigned char *key, unsigned int keyLen,
unsigned int tagLen)
{
ChaCha20Poly1305Context *ctx;
ctx = PORT_New(ChaCha20Poly1305Context);
if (ctx == NULL) {
return NULL;
}
if (ChaCha20Poly1305_InitContext(ctx, key, keyLen, tagLen) != SECSuccess) {
PORT_Free(ctx);
ctx = NULL;
}
return ctx;
}
void
ChaCha20Poly1305_DestroyContext(ChaCha20Poly1305Context *ctx, PRBool freeit)
{
PORT_Memset(ctx, 0, sizeof(*ctx));
if (freeit) {
PORT_Free(ctx);
}
}
SECStatus
ChaCha20Poly1305_Seal(const ChaCha20Poly1305Context *ctx, unsigned char *output,
unsigned int *outputLen, unsigned int maxOutputLen,
const unsigned char *input, unsigned int inputLen,
const unsigned char *nonce, unsigned int nonceLen,
const unsigned char *ad, unsigned int adLen)
{
unsigned char block[64];
unsigned char tag[16];
if (nonceLen != 12) {
PORT_SetError(SEC_ERROR_INPUT_LEN);
return SECFailure;
}
*outputLen = inputLen + ctx->tagLen;
if (maxOutputLen < *outputLen) {
PORT_SetError(SEC_ERROR_OUTPUT_LEN);
return SECFailure;
}
PORT_Memset(block, 0, sizeof(block));
// Generate a block of keystream. The first 32 bytes will be the poly1305
// key. The remainder of the block is discarded.
ChaCha20XOR(block, block, sizeof(block), ctx->key, nonce, 0);
ChaCha20XOR(output, input, inputLen, ctx->key, nonce, 1);
Poly1305Do(tag, ad, adLen, output, inputLen, block);
PORT_Memcpy(output + inputLen, tag, ctx->tagLen);
return SECSuccess;
}
SECStatus
ChaCha20Poly1305_Open(const ChaCha20Poly1305Context *ctx, unsigned char *output,
unsigned int *outputLen, unsigned int maxOutputLen,
const unsigned char *input, unsigned int inputLen,
const unsigned char *nonce, unsigned int nonceLen,
const unsigned char *ad, unsigned int adLen)
{
unsigned char block[64];
unsigned char tag[16];
if (nonceLen != 12) {
PORT_SetError(SEC_ERROR_INPUT_LEN);
return SECFailure;
}
if (inputLen < ctx->tagLen) {
PORT_SetError(SEC_ERROR_INPUT_LEN);
return SECFailure;
}
unsigned int ciphertextLen = inputLen - ctx->tagLen;
*outputLen = ciphertextLen;
if (maxOutputLen < *outputLen) {
PORT_SetError(SEC_ERROR_OUTPUT_LEN);
return SECFailure;
}
PORT_Memset(block, 0, sizeof(block));
// Generate a block of keystream. The first 32 bytes will be the poly1305
// key. The remainder of the block is discarded.
ChaCha20XOR(block, block, sizeof(block), ctx->key, nonce, 0);
Poly1305Do(tag, ad, adLen, input, ciphertextLen, block);
if (NSS_SecureMemcmp(tag, &input[ciphertextLen], ctx->tagLen) != 0) {
PORT_SetError(SEC_ERROR_BAD_DATA);
return SECFailure;
}
ChaCha20XOR(output, input, ciphertextLen, ctx->key, nonce, 1);
return SECSuccess;
}
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