98 lines
2.7 KiB
C
98 lines
2.7 KiB
C
/// @file utils_prng.c
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/// @brief The implementation of PRNG related functions.
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///
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#include "utils_prng.h"
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#include "aes.h"
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#include "randombytes.h"
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#include "utils_hash.h"
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#include <stdlib.h>
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#include <string.h>
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static void prng_update(const unsigned char *provided_data,
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unsigned char *Key,
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unsigned char *V) {
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unsigned char temp[48];
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aes256ctx ctx;
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aes256_ecb_keyexp(&ctx, Key);
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for (int i = 0; i < 3; i++) {
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//increment V
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for (int j = 15; j >= 0; j--) {
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if (V[j] == 0xff) {
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V[j] = 0x00;
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} else {
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V[j]++;
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break;
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}
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}
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aes256_ecb(temp + 16 * i, V, 1, &ctx);
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}
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if (provided_data != NULL) {
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for (int i = 0; i < 48; i++) {
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temp[i] ^= provided_data[i];
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}
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}
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aes256_ctx_release(&ctx);
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memcpy(Key, temp, 32);
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memcpy(V, temp + 32, 16);
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}
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static void randombytes_init_with_state(prng_t *state,
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unsigned char *entropy_input_48bytes) {
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memset(state->Key, 0x00, 32);
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memset(state->V, 0x00, 16);
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prng_update(entropy_input_48bytes, state->Key, state->V);
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}
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static int randombytes_with_state(prng_t *state,
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unsigned char *x,
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size_t xlen) {
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unsigned char block[16];
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int i = 0;
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aes256ctx ctx;
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aes256_ecb_keyexp(&ctx, state->Key);
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while (xlen > 0) {
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//increment V
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for (int j = 15; j >= 0; j--) {
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if (state->V[j] == 0xff) {
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state->V[j] = 0x00;
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} else {
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state->V[j]++;
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break;
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}
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}
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aes256_ecb(block, state->V, 1, &ctx);
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if (xlen > 15) {
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memcpy(x + i, block, 16);
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i += 16;
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xlen -= 16;
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} else {
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memcpy(x + i, block, xlen);
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xlen = 0;
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}
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}
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aes256_ctx_release(&ctx);
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prng_update(NULL, state->Key, state->V);
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return 0;
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}
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int PQCLEAN_RAINBOWVCIRCUMZENITHAL_CLEAN_prng_set(prng_t *ctx, const void *prng_seed, unsigned long prng_seedlen) {
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unsigned char seed[48];
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if (prng_seedlen >= 48) {
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memcpy(seed, prng_seed, 48);
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} else {
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memcpy(seed, prng_seed, prng_seedlen);
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PQCLEAN_RAINBOWVCIRCUMZENITHAL_CLEAN_hash_msg(seed + prng_seedlen, 48 - (unsigned)prng_seedlen, (const unsigned char *)prng_seed, prng_seedlen);
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}
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randombytes_init_with_state(ctx, seed);
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return 0;
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}
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int PQCLEAN_RAINBOWVCIRCUMZENITHAL_CLEAN_prng_gen(prng_t *ctx, unsigned char *out, unsigned long outlen) {
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return randombytes_with_state(ctx, out, outlen);
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}
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