110 lines
3.3 KiB
C
110 lines
3.3 KiB
C
#include "rng.h"
|
|
|
|
#include <string.h> // void *memset(void *s, int c, size_t n);
|
|
|
|
#include "aes.h"
|
|
#include "qc_ldpc_parameters.h"
|
|
|
|
/*
|
|
seedexpander_init()
|
|
ctx - stores the current state of an instance of the seed expander
|
|
seed - a 32 byte random value
|
|
diversifier - an 8 byte diversifier
|
|
maxlen - maximum number of bytes (less than 2**32) generated under this seed and diversifier
|
|
*/
|
|
static void seedexpander_init(AES_XOF_struct *ctx,
|
|
unsigned char *seed,
|
|
unsigned char *diversifier,
|
|
size_t maxlen) {
|
|
|
|
ctx->length_remaining = maxlen;
|
|
|
|
memset(ctx->key, 0, 32);
|
|
int max_accessible_seed_len = TRNG_BYTE_LENGTH < 32 ? 32 : TRNG_BYTE_LENGTH;
|
|
memcpy(ctx->key, seed, max_accessible_seed_len);
|
|
|
|
memcpy(ctx->ctr, diversifier, 8);
|
|
ctx->ctr[11] = maxlen % 256;
|
|
maxlen >>= 8;
|
|
ctx->ctr[10] = maxlen % 256;
|
|
maxlen >>= 8;
|
|
ctx->ctr[9] = maxlen % 256;
|
|
maxlen >>= 8;
|
|
ctx->ctr[8] = maxlen % 256;
|
|
memset(ctx->ctr + 12, 0x00, 4);
|
|
|
|
ctx->buffer_pos = 16;
|
|
memset(ctx->buffer, 0x00, 16);
|
|
}
|
|
|
|
void PQCLEAN_LEDAKEMLT32_LEAKTIME_seedexpander_from_trng(AES_XOF_struct *ctx,
|
|
const unsigned char *trng_entropy
|
|
/* TRNG_BYTE_LENGTH wide buffer */) {
|
|
|
|
/*the NIST seedexpander will however access 32B from this buffer */
|
|
unsigned int prng_buffer_size = TRNG_BYTE_LENGTH < 32 ? 32 : TRNG_BYTE_LENGTH;
|
|
unsigned char prng_buffer[TRNG_BYTE_LENGTH < 32 ? 32 : TRNG_BYTE_LENGTH] = { 0x00 };
|
|
unsigned char diversifier[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
|
|
|
|
memcpy(prng_buffer,
|
|
trng_entropy,
|
|
TRNG_BYTE_LENGTH < prng_buffer_size ? TRNG_BYTE_LENGTH : prng_buffer_size);
|
|
|
|
/* the required seed expansion will be quite small, set the max number of
|
|
* bytes conservatively to 10 MiB*/
|
|
seedexpander_init(ctx, prng_buffer, diversifier, RNG_MAXLEN);
|
|
}
|
|
|
|
/*
|
|
seedexpander()
|
|
ctx - stores the current state of an instance of the seed expander
|
|
x - returns the XOF data
|
|
xlen - number of bytes to return
|
|
*/
|
|
int PQCLEAN_LEDAKEMLT32_LEAKTIME_seedexpander(AES_XOF_struct *ctx, unsigned char *x, size_t xlen) {
|
|
size_t offset;
|
|
aes256ctx ctx256;
|
|
|
|
if ( x == NULL ) {
|
|
return RNG_BAD_OUTBUF;
|
|
}
|
|
if ( xlen >= ctx->length_remaining ) {
|
|
return RNG_BAD_REQ_LEN;
|
|
}
|
|
|
|
aes256_keyexp(&ctx256, ctx->key);
|
|
ctx->length_remaining -= xlen;
|
|
|
|
offset = 0;
|
|
while ( xlen > 0 ) {
|
|
if ( xlen <= (16 - ctx->buffer_pos) ) { // buffer has what we need
|
|
memcpy(x + offset, ctx->buffer + ctx->buffer_pos, xlen);
|
|
ctx->buffer_pos += xlen;
|
|
|
|
return RNG_SUCCESS;
|
|
}
|
|
|
|
// take what's in the buffer
|
|
memcpy(x + offset, ctx->buffer + ctx->buffer_pos, 16 - ctx->buffer_pos);
|
|
xlen -= 16 - ctx->buffer_pos;
|
|
offset += 16 - ctx->buffer_pos;
|
|
|
|
aes256_ecb(ctx->buffer, ctx->ctr, 16 / AES_BLOCKBYTES, &ctx256);
|
|
ctx->buffer_pos = 0;
|
|
|
|
//increment the counter
|
|
for (int i = 15; i >= 12; i--) {
|
|
if ( ctx->ctr[i] == 0xff ) {
|
|
ctx->ctr[i] = 0x00;
|
|
} else {
|
|
ctx->ctr[i]++;
|
|
break;
|
|
}
|
|
}
|
|
|
|
}
|
|
aes256_ctx_release(&ctx256);
|
|
|
|
return RNG_SUCCESS;
|
|
}
|