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