int wots_pkFromSig()

in xmss_wots.c [158:191]

• 27 lines of code
• 5 McCabe index (conditional complexity)

int wots_pkFromSig(unsigned char *pk, const unsigned char *sig, const unsigned char *msg, const wots_params *params, const unsigned char *pub_seed, uint32_t addr[8])
{
  int csum = 0;
  uint32_t i = 0;
  int *basew = calloc(params->len, sizeof(int));
  if (basew == NULL)
    return -1;

  base_w(basew, params->len_1, msg, params);

  for (i=0; i < params->len_1; i++) {
    csum += params->w - 1 - basew[i];
  }

  csum = csum << (8 - ((params->len_2 * params->log_w) % 8));

  int len_2_bytes = ((params->len_2 * params->log_w) + 7) / 8;

  unsigned char csum_bytes[len_2_bytes];
  to_byte(csum_bytes, csum, len_2_bytes);

  int csum_basew[params->len_2];
  base_w(csum_basew, params->len_2, csum_bytes, params);

  for (i = 0; i < params->len_2; i++) {
    basew[params->len_1 + i] = csum_basew[i];
  }
  for (i=0; i < params->len; i++) {
    setChainADRS(addr, i);
    gen_chain(pk+i*params->n, sig+i*params->n, basew[i], params->w-1-basew[i], params, pub_seed, addr);
  }
  free(basew);
  return 0;
}