int foundation_rngV1_generate(uint8_t newkey[CHACHA_KEY_SIZE], uint8_t *dst, uint8_t key[CHACHA_KEY_SIZE], FsCountOf bytes)
{
const int rounds = 20;
uint8_t nonce[CHACHA_NONCE_SIZE] = { 0 };
uint8_t buf[CHACHA_OUTPUT_SIZE]; /* for partial buffer */
if (!bytes)
return 0;
for (; bytes >= CHACHA_OUTPUT_SIZE; bytes -= CHACHA_OUTPUT_SIZE, dst += CHACHA_OUTPUT_SIZE) {
chacha_core(rounds, dst, key, nonce);
if (++nonce[0] == 0)
nonce[1]++;
}
assert(bytes < CHACHA_OUTPUT_SIZE);
chacha_core(rounds, buf, key, nonce);
int remaining = CHACHA_OUTPUT_SIZE - bytes;
if (remaining >= CHACHA_KEY_SIZE) {
memcpy(dst, buf, bytes);
memcpy(newkey, buf + bytes, CHACHA_KEY_SIZE);
} else {
memcpy(dst, buf, bytes);
if (++nonce[0] == 0)
nonce[1]++;
chacha_core(rounds, buf, key, nonce);
memcpy(newkey, buf, CHACHA_KEY_SIZE);
}
memset(buf, 0, CHACHA_OUTPUT_SIZE);
return 0;
}
void cryptonite_chacha_combine(uint8_t *dst, cryptonite_chacha_context *ctx, const uint8_t *src, uint32_t bytes)
{
block out;
cryptonite_chacha_state *st;
int i;
if (!bytes)
return;
/* xor the previous buffer first (if any) */
if (ctx->prev_len > 0) {
int to_copy = (ctx->prev_len < bytes) ? ctx->prev_len : bytes;
for (i = 0; i < to_copy; i++)
dst[i] = src[i] ^ ctx->prev[ctx->prev_ofs+i];
memset(ctx->prev + ctx->prev_ofs, 0, to_copy);
ctx->prev_len -= to_copy;
ctx->prev_ofs += to_copy;
src += to_copy;
dst += to_copy;
bytes -= to_copy;
}
if (bytes == 0)
return;
st = &ctx->st;
/* xor new 64-bytes chunks and store the left over if any */
for (; bytes >= 64; bytes -= 64, src += 64, dst += 64) {
/* generate new chunk and update state */
chacha_core(ctx->nb_rounds, &out, st);
st->d[12] += 1;
if (st->d[12] == 0)
st->d[13] += 1;
for (i = 0; i < 64; ++i)
dst[i] = src[i] ^ out.b[i];
}
if (bytes > 0) {
/* generate new chunk and update state */
chacha_core(ctx->nb_rounds, &out, st);
st->d[12] += 1;
if (st->d[12] == 0)
st->d[13] += 1;
/* xor as much as needed */
for (i = 0; i < bytes; i++)
dst[i] = src[i] ^ out.b[i];
/* copy the left over in the buffer */
ctx->prev_len = 64 - bytes;
ctx->prev_ofs = i;
for (; i < 64; i++) {
ctx->prev[i] = out.b[i];
}
}
}
void cryptonite_chacha_random(uint32_t rounds, uint8_t *dst, cryptonite_chacha_state *st, uint32_t bytes)
{
block out;
if (!bytes)
return;
for (; bytes >= 16; bytes -= 16, dst += 16) {
chacha_core(rounds, &out, st);
memcpy(dst, out.b + 40, 16);
cryptonite_chacha_init_core(st, 32, out.b, 8, out.b + 32);
}
if (bytes) {
chacha_core(rounds, &out, st);
memcpy(dst, out.b + 40, bytes);
cryptonite_chacha_init_core(st, 32, out.b, 8, out.b + 32);
}
}
