mirror of
https://github.com/henrydcase/pqc.git
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304 lines
9.0 KiB
C
304 lines
9.0 KiB
C
#include "rng.h"
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h> // void srand(unsigned int seed); int rand(void); RAND_MAX
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#include <string.h> // void *memset(void *s, int c, size_t n);
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#define __USE_POSIX199309
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#include <time.h> // struct timespec; clock_gettime(...); CLOCK_REALTIME
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#include "aes256.h"
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#include "qc_ldpc_parameters.h"
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/******************************************************************************/
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/*----------------------------------------------------------------------------*/
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/* start PSEUDO-RAND GENERATOR ROUTINES for rnd.h */
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/*----------------------------------------------------------------------------*/
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void initialize_pseudo_random_generator_seed(int ac, char *av[]) {
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if (ac == 2) {
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srand(atoi(av[1]));
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} else {
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struct timespec seedValue;
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clock_gettime(CLOCK_REALTIME, &seedValue);
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srand(seedValue.tv_nsec);
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} // end else-if
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unsigned char pseudo_entropy[48];
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for (int i = 0; i < 48; i++) {
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pseudo_entropy[i] = rand() & 0xff;
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}
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randombytes_init(pseudo_entropy,
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NULL,
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0 /*unused in NIST function*/);
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} // end initilize_pseudo_random_sequence_seed
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/*----------------------------------------------------------------------------*/
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/* Initializes a dedicated DRBG context to avoid conflicts with the global one
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* declared by NIST for KATs. Provides the output of the DRBG in output, for
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* the given length */
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/*----------------------------------------------------------------------------*/
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/* end PSEUDO-RAND GENERATOR ROUTINES for rnd.h */
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/*----------------------------------------------------------------------------*/
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AES256_CTR_DRBG_struct DRBG_ctx;
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void AES256_ECB(unsigned char *key, unsigned char *ctr,
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unsigned char *buffer);
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/*
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seedexpander_init()
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ctx - stores the current state of an instance of the seed expander
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seed - a 32 byte random value
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diversifier - an 8 byte diversifier
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maxlen - maximum number of bytes (less than 2**32) generated under this seed and diversifier
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*/
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int
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seedexpander_init(AES_XOF_struct *ctx,
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unsigned char *seed,
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unsigned char *diversifier,
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unsigned long maxlen) {
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if ( maxlen >= 0x100000000 ) {
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return RNG_BAD_MAXLEN;
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}
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ctx->length_remaining = maxlen;
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memset(ctx->key, 0, 32);
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int max_accessible_seed_len = TRNG_BYTE_LENGTH < 32 ? 32 : TRNG_BYTE_LENGTH;
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memcpy(ctx->key, seed, max_accessible_seed_len);
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memcpy(ctx->ctr, diversifier, 8);
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ctx->ctr[11] = maxlen % 256;
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maxlen >>= 8;
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ctx->ctr[10] = maxlen % 256;
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maxlen >>= 8;
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ctx->ctr[9] = maxlen % 256;
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maxlen >>= 8;
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ctx->ctr[8] = maxlen % 256;
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memset(ctx->ctr + 12, 0x00, 4);
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ctx->buffer_pos = 16;
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memset(ctx->buffer, 0x00, 16);
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return RNG_SUCCESS;
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}
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/*
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seedexpander()
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ctx - stores the current state of an instance of the seed expander
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x - returns the XOF data
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xlen - number of bytes to return
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*/
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int
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seedexpander(AES_XOF_struct *ctx, unsigned char *x, unsigned long xlen) {
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unsigned long offset;
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if ( x == NULL ) {
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return RNG_BAD_OUTBUF;
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}
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if ( xlen >= ctx->length_remaining ) {
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return RNG_BAD_REQ_LEN;
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}
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ctx->length_remaining -= xlen;
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offset = 0;
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while ( xlen > 0 ) {
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if ( xlen <= (16 - ctx->buffer_pos) ) { // buffer has what we need
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memcpy(x + offset, ctx->buffer + ctx->buffer_pos, xlen);
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ctx->buffer_pos += xlen;
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return RNG_SUCCESS;
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}
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// take what's in the buffer
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memcpy(x + offset, ctx->buffer + ctx->buffer_pos, 16 - ctx->buffer_pos);
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xlen -= 16 - ctx->buffer_pos;
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offset += 16 - ctx->buffer_pos;
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AES256_ECB(ctx->key, ctx->ctr, ctx->buffer);
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ctx->buffer_pos = 0;
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//increment the counter
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for (int i = 15; i >= 12; i--) {
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if ( ctx->ctr[i] == 0xff ) {
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ctx->ctr[i] = 0x00;
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} else {
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ctx->ctr[i]++;
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break;
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}
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}
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}
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return RNG_SUCCESS;
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}
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// Use whatever AES implementation you have. This uses AES from openSSL library
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// key - 256-bit AES key
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// ptx - a 128-bit plaintext value
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// ctx - a 128-bit ciphertext value
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void
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AES256_ECB(unsigned char *key, unsigned char *ptx, unsigned char *ctx) {
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uint32_t round_key[4 * (NROUNDS + 1)] = {0x00};
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rijndaelKeySetupEnc(round_key, key, KEYLEN_b);
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rijndaelEncrypt(round_key, NROUNDS, ptx, ctx);
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}
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void
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randombytes_init(unsigned char *entropy_input,
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unsigned char *personalization_string,
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int security_strength) {
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unsigned char seed_material[48];
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memcpy(seed_material, entropy_input, 48);
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if (personalization_string)
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for (int i = 0; i < 48; i++) {
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seed_material[i] ^= personalization_string[i];
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}
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memset(DRBG_ctx.Key, 0x00, 32);
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memset(DRBG_ctx.V, 0x00, 16);
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AES256_CTR_DRBG_Update(seed_material, DRBG_ctx.Key, DRBG_ctx.V);
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DRBG_ctx.reseed_counter = 1;
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}
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int
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randombytes(unsigned char *x, unsigned long long xlen) {
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unsigned char block[16];
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int i = 0;
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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 ( DRBG_ctx.V[j] == 0xff ) {
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DRBG_ctx.V[j] = 0x00;
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} else {
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DRBG_ctx.V[j]++;
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break;
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}
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}
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AES256_ECB(DRBG_ctx.Key, DRBG_ctx.V, block);
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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_CTR_DRBG_Update(NULL, DRBG_ctx.Key, DRBG_ctx.V);
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DRBG_ctx.reseed_counter++;
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return RNG_SUCCESS;
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}
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void
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AES256_CTR_DRBG_Update(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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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(Key, V, temp + 16 * i);
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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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memcpy(Key, temp, 32);
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memcpy(V, temp + 32, 16);
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}
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void deterministic_random_byte_generator(unsigned char *const output,
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const unsigned long long output_len,
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const unsigned char *const seed,
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const unsigned long long seed_length
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) {
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/* DRBG context initialization */
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AES256_CTR_DRBG_struct ctx;
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unsigned char seed_material[48];
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memset(seed_material, 0x00, 48);
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memcpy(seed_material, seed, seed_length);
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memset(ctx.Key, 0x00, 32);
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memset(ctx.V, 0x00, 16);
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AES256_CTR_DRBG_Update(seed_material, ctx.Key, ctx.V);
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ctx.reseed_counter = 1;
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/* Actual DRBG computation as from the randombytes(unsigned char *x,
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* unsigned long long xlen) from NIST */
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unsigned char block[16];
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int i = 0, length_remaining;
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length_remaining = output_len;
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while ( length_remaining > 0 ) {
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//increment V
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for (int j = 15; j >= 0; j--) {
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if ( ctx.V[j] == 0xff ) {
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ctx.V[j] = 0x00;
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} else {
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ctx.V[j]++;
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break;
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}
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}
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AES256_ECB(ctx.Key, ctx.V, block);
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if ( length_remaining > 15 ) {
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memcpy(output + i, block, 16);
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i += 16;
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length_remaining -= 16;
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} else {
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memcpy(output + i, block, length_remaining);
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length_remaining = 0;
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}
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}
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AES256_CTR_DRBG_Update(NULL, ctx.Key, ctx.V);
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ctx.reseed_counter++;
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} // end deterministic_random_byte_generator
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void seedexpander_from_trng(AES_XOF_struct *ctx,
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const unsigned char *trng_entropy
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/* TRNG_BYTE_LENGTH wide buffer */) {
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/*the NIST seedexpander will however access 32B from this buffer */
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unsigned int prng_buffer_size = TRNG_BYTE_LENGTH < 32 ? 32 : TRNG_BYTE_LENGTH;
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unsigned char prng_buffer[TRNG_BYTE_LENGTH < 32 ? 32 : TRNG_BYTE_LENGTH] = { 0x00 };
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memcpy(prng_buffer,
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trng_entropy,
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TRNG_BYTE_LENGTH < prng_buffer_size ? TRNG_BYTE_LENGTH : prng_buffer_size);
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/* if extra entropy is provided, add it to the diversifier */
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#if TRNG_BYTE_LENGTH == 40
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unsigned char *diversifier = ((unsigned char *)trng_entropy) + 32;
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#else
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unsigned char diversifier[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
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#endif
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/* the required seed expansion will be quite small, set the max number of
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* bytes conservatively to 10 MiB*/
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seedexpander_init(ctx, prng_buffer, diversifier, 10 * 1024 * 1024);
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}
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