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Create chacha20.c

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Evan Su 2021-03-22 09:14:10 -04:00 committed by GitHub
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/* ===================================================================
*
* Copyright (c) 2014, Legrandin <helderijs@gmail.com>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS 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
* COPYRIGHT HOLDER OR 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.
* ===================================================================
*/
#include "common.h"
#include "endianess.h"
FAKE_INIT(chacha20)
#define KEY_SIZE 32
typedef struct {
/** Initial state for the next iteration **/
uint32_t h[16];
size_t nonceSize; /** in bytes **/
/** How many bytes at the beginning of the key stream
* have already been used.
*/
unsigned usedKeyStream;
uint8_t keyStream[sizeof(uint32_t)*16];
} stream_state;
#define ROTL(q, n) (((q) << (n)) | ((q) >> (32 - (n))))
#define QR(a, b, c, d) {\
a+=b; d^=a; d=ROTL(d,16); \
c+=d; b^=c; b=ROTL(b,12); \
a+=b; d^=a; d=ROTL(d,8); \
c+=d; b^=c; b=ROTL(b,7); \
}
EXPORT_SYM int chacha20_init(stream_state **pState,
const uint8_t *key,
size_t keySize,
const uint8_t *nonce,
size_t nonceSize)
{
stream_state *hs;
unsigned i;
if (NULL == pState || NULL == nonce)
return ERR_NULL;
if (NULL == key || keySize != KEY_SIZE)
return ERR_KEY_SIZE;
if (nonceSize != 8 && nonceSize != 12 && nonceSize != 16)
return ERR_NONCE_SIZE;
*pState = hs = (stream_state*) calloc(1, sizeof(stream_state));
if (NULL == hs)
return ERR_MEMORY;
hs->h[0] = 0x61707865;
hs->h[1] = 0x3320646e;
hs->h[2] = 0x79622d32;
hs->h[3] = 0x6b206574;
/** Move 256-bit/32-byte key into h[4..11] **/
for (i=0; i<32/4; i++) {
hs->h[4+i] = LOAD_U32_LITTLE(key + 4*i);
}
switch (nonceSize) {
case 8: {
/*
cccccccc cccccccc cccccccc cccccccc
kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk
kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk
bbbbbbbb BBBBBBBB nnnnnnnn nnnnnnnn
c=constant k=key b=blockcount(low) B=blockcount(high) n=nonce
*/
/** h[12] remains 0 (offset) **/
/** h[13] remains 0 (offset) **/
hs->h[14] = LOAD_U32_LITTLE(nonce + 0);
hs->h[15] = LOAD_U32_LITTLE(nonce + 4);
break;
}
case 12: {
/*
cccccccc cccccccc cccccccc cccccccc
kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk
kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk
bbbbbbbb nnnnnnnn nnnnnnnn nnnnnnnn
c=constant k=key b=blockcount n=nonce
*/
/** h[12] remains 0 (offset) **/
hs->h[13] = LOAD_U32_LITTLE(nonce + 0);
hs->h[14] = LOAD_U32_LITTLE(nonce + 4);
hs->h[15] = LOAD_U32_LITTLE(nonce + 8);
break;
}
case 16: {
/*
cccccccc cccccccc cccccccc cccccccc
kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk
kkkkkkkk kkkkkkkk kkkkkkkk kkkkkkkk
nnnnnnnn nnnnnnnn nnnnnnnn nnnnnnnn
c=constant k=key n=nonce
*/
hs->h[12] = LOAD_U32_LITTLE(nonce + 0);
hs->h[13] = LOAD_U32_LITTLE(nonce + 4);
hs->h[14] = LOAD_U32_LITTLE(nonce + 8);
hs->h[15] = LOAD_U32_LITTLE(nonce + 12);
break;
}
default:
return ERR_NONCE_SIZE;
}
hs->nonceSize = nonceSize;
hs->usedKeyStream = sizeof hs->keyStream;
return 0;
}
EXPORT_SYM int chacha20_destroy(stream_state *state)
{
if (NULL == state)
return ERR_NULL;
free(state);
return 0;
}
static int chacha20_core(stream_state *state, uint32_t h[16])
{
unsigned i;
memcpy(h, state->h, sizeof state->h);
for (i=0; i<10; i++) {
/** Column round **/
QR(h[0], h[4], h[ 8], h[12]);
QR(h[1], h[5], h[ 9], h[13]);
QR(h[2], h[6], h[10], h[14]);
QR(h[3], h[7], h[11], h[15]);
/** Diagonal round **/
QR(h[0], h[5], h[10], h[15]);
QR(h[1], h[6], h[11], h[12]);
QR(h[2], h[7], h[ 8], h[13]);
QR(h[3], h[4], h[ 9], h[14]);
}
for (i=0; i<16; i++) {
uint32_t sum;
sum = h[i] + state->h[i];
STORE_U32_LITTLE(state->keyStream + 4*i, sum);
}
state->usedKeyStream = 0;
switch (state->nonceSize) {
case 8: {
/** Nonce is 64 bits, counter is two words **/
if (++state->h[12] == 0) {
if (++state->h[13] == 0) {
return ERR_MAX_DATA;
}
}
break;
}
case 12: {
/** Nonce is 96 bits, counter is one word **/
if (++state->h[12] == 0) {
return ERR_MAX_DATA;
}
break;
}
case 16: {
/** Nonce is 192 bits, there is no counter as this is intended
* to be run once only (HChaCha20) **/
break;
}
}
return 0;
}
EXPORT_SYM int chacha20_encrypt(stream_state *state,
const uint8_t in[],
uint8_t out[],
size_t len)
{
if (NULL == state || NULL == in || NULL == out)
return ERR_NULL;
if ((state->nonceSize != 8) && (state->nonceSize != 12))
return ERR_NONCE_SIZE;
while (len>0) {
unsigned keyStreamToUse;
unsigned i;
uint32_t h[16];
if (state->usedKeyStream == sizeof state->keyStream) {
int result;
result = chacha20_core(state, h);
if (result)
return result;
}
keyStreamToUse = (unsigned)MIN(len, sizeof state->keyStream - state->usedKeyStream);
for (i=0; i<keyStreamToUse; i++)
*out++ = *in++ ^ state->keyStream[i + state->usedKeyStream];
len -= keyStreamToUse;
state->usedKeyStream += keyStreamToUse;
}
return 0;
}
EXPORT_SYM int chacha20_seek(stream_state *state,
unsigned long block_high,
unsigned long block_low,
unsigned offset)
{
int result;
uint32_t h[16];
if (NULL == state)
return ERR_NULL;
if ((state->nonceSize != 8) && (state->nonceSize != 12))
return ERR_NONCE_SIZE;
if (offset >= sizeof state->keyStream)
return ERR_MAX_OFFSET;
if (state->nonceSize == 8) {
/** Nonce is 64 bits, counter is two words **/
state->h[12] = (uint32_t)block_low;
state->h[13] = (uint32_t)block_high;
} else {
/** Nonce is 96 bits, counter is one word **/
if (block_high > 0) {
return ERR_MAX_OFFSET;
}
state->h[12] = (uint32_t)block_low;
}
result = chacha20_core(state, h);
if (result)
return result;
state->usedKeyStream = offset;
return 0;
}
/*
* Based on https://tools.ietf.org/html/draft-arciszewski-xchacha-03
*/
EXPORT_SYM int hchacha20(const uint8_t key[KEY_SIZE],
const uint8_t nonce16[16], /* First 16 bytes of the 24 byte nonce */
uint8_t subkey[KEY_SIZE])
{
stream_state *pState;
uint32_t h[16];
if (NULL == key || NULL == nonce16 || NULL == subkey) {
return ERR_NULL;
}
chacha20_init(&pState, key, KEY_SIZE, nonce16, 16);
if (NULL == pState)
return ERR_MEMORY;
chacha20_core(pState, h);
/* We only keep first and last row from the new state */
STORE_U32_LITTLE(subkey + 0, h[0]);
STORE_U32_LITTLE(subkey + 4, h[1]);
STORE_U32_LITTLE(subkey + 8, h[2]);
STORE_U32_LITTLE(subkey + 12, h[3]);
STORE_U32_LITTLE(subkey + 16, h[12]);
STORE_U32_LITTLE(subkey + 20, h[13]);
STORE_U32_LITTLE(subkey + 24, h[14]);
STORE_U32_LITTLE(subkey + 28, h[15]);
chacha20_destroy(pState);
return 0;
}
#ifdef PROFILE
int main(void)
{
const unsigned data_size = 1024*1024;
const uint8_t key[32] = "12345678901234561234567890123456";
const uint8_t nonce[8] = "12345678";
stream_state *state;
uint8_t *data;
data = malloc(data_size);
for (int i=0; i<data_size; i++) {
data[i] = (uint8_t) i;
}
chacha20_init(&state, key, 32, nonce, 8);
for (int i=0; i<1024; i++)
chacha20_encrypt(state, data, data, data_size);
chacha20_destroy(state);
free(data);
}
#endif