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#include "inner.h"
#include <assert.h>
/*
* PRNG and interface to the system RNG.
*
* ==========================(LICENSE BEGIN)============================
*
* Copyright (c) 2017-2019 Falcon Project
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* ===========================(LICENSE END)=============================
*
* @author Thomas Pornin <thomas.pornin@nccgroup.com>
*/
/*
* Include relevant system header files. For Win32, this will also need
* linking with advapi32.dll, which we trigger with an appropriate #pragma.
*/
/* see inner.h */
int
PQCLEAN_FALCON1024_CLEAN_get_seed(void *seed, size_t len) {
(void)seed;
if (len == 0) {
return 1;
}
return 0;
}
/* see inner.h */
void
PQCLEAN_FALCON1024_CLEAN_prng_init(prng *p, inner_shake256_context *src) {
/*
* To ensure reproducibility for a given seed, we
* must enforce little-endian interpretation of
* the state words.
*/
uint8_t tmp[56];
uint64_t th, tl;
int i;
inner_shake256_extract(src, tmp, 56);
for (i = 0; i < 14; i ++) {
uint32_t w;
w = (uint32_t)tmp[(i << 2) + 0]
| ((uint32_t)tmp[(i << 2) + 1] << 8)
| ((uint32_t)tmp[(i << 2) + 2] << 16)
| ((uint32_t)tmp[(i << 2) + 3] << 24);
*(uint32_t *)(p->state.d + (i << 2)) = w;
}
tl = *(uint32_t *)(p->state.d + 48);
th = *(uint32_t *)(p->state.d + 52);
*(uint64_t *)(p->state.d + 48) = tl + (th << 32);
PQCLEAN_FALCON1024_CLEAN_prng_refill(p);
}
/*
* PRNG based on ChaCha20.
*
* State consists in key (32 bytes) then IV (16 bytes) and block counter
* (8 bytes). Normally, we should not care about local endianness (this
* is for a PRNG), but for the NIST competition we need reproducible KAT
* vectors that work across architectures, so we enforce little-endian
* interpretation where applicable. Moreover, output words are "spread
* out" over the output buffer with the interleaving pattern that is
* naturally obtained from the AVX2 implementation that runs eight
* ChaCha20 instances in parallel.
*
* The block counter is XORed into the first 8 bytes of the IV.
*/
void
PQCLEAN_FALCON1024_CLEAN_prng_refill(prng *p) {
static const uint32_t CW[] = {
0x61707865, 0x3320646e, 0x79622d32, 0x6b206574
};
uint64_t cc;
size_t u;
/*
* State uses local endianness. Only the output bytes must be
* converted to little endian (if used on a big-endian machine).
*/
cc = *(uint64_t *)(p->state.d + 48);
for (u = 0; u < 8; u ++) {
uint32_t state[16];
size_t v;
int i;
memcpy(&state[0], CW, sizeof CW);
memcpy(&state[4], p->state.d, 48);
state[14] ^= (uint32_t)cc;
state[15] ^= (uint32_t)(cc >> 32);
for (i = 0; i < 10; i ++) {
#define QROUND(a, b, c, d) do { \
state[a] += state[b]; \
state[d] ^= state[a]; \
state[d] = (state[d] << 16) | (state[d] >> 16); \
state[c] += state[d]; \
state[b] ^= state[c]; \
state[b] = (state[b] << 12) | (state[b] >> 20); \
state[a] += state[b]; \
state[d] ^= state[a]; \
state[d] = (state[d] << 8) | (state[d] >> 24); \
state[c] += state[d]; \
state[b] ^= state[c]; \
state[b] = (state[b] << 7) | (state[b] >> 25); \
} while (0)
QROUND( 0, 4, 8, 12);
QROUND( 1, 5, 9, 13);
QROUND( 2, 6, 10, 14);
QROUND( 3, 7, 11, 15);
QROUND( 0, 5, 10, 15);
QROUND( 1, 6, 11, 12);
QROUND( 2, 7, 8, 13);
QROUND( 3, 4, 9, 14);
#undef QROUND
}
for (v = 0; v < 4; v ++) {
state[v] += CW[v];
}
for (v = 4; v < 14; v ++) {
state[v] += ((uint32_t *)p->state.d)[v - 4];
}
state[14] += ((uint32_t *)p->state.d)[10]
^ (uint32_t)cc;
state[15] += ((uint32_t *)p->state.d)[11]
^ (uint32_t)(cc >> 32);
cc ++;
/*
* We mimic the interleaving that is used in the AVX2
* implementation.
*/
for (v = 0; v < 16; v ++) {
p->buf.d[(u << 2) + (v << 5) + 0] =
(uint8_t)state[v];
p->buf.d[(u << 2) + (v << 5) + 1] =
(uint8_t)(state[v] >> 8);
p->buf.d[(u << 2) + (v << 5) + 2] =
(uint8_t)(state[v] >> 16);
p->buf.d[(u << 2) + (v << 5) + 3] =
(uint8_t)(state[v] >> 24);
}
}
*(uint64_t *)(p->state.d + 48) = cc;
p->ptr = 0;
}
/* see inner.h */
void
PQCLEAN_FALCON1024_CLEAN_prng_get_bytes(prng *p, void *dst, size_t len) {
uint8_t *buf;
buf = dst;
while (len > 0) {
size_t clen;
clen = (sizeof p->buf.d) - p->ptr;
if (clen > len) {
clen = len;
}
memcpy(buf, p->buf.d, clen);
buf += clen;
len -= clen;
p->ptr += clen;
if (p->ptr == sizeof p->buf.d) {
PQCLEAN_FALCON1024_CLEAN_prng_refill(p);
}
}
}
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