/*
 *  primegen.c
 *
 * Generates random integers which are prime with a high degree of
 * probability using the Miller-Rabin probabilistic primality testing
 * algorithm.
 *
 * Usage:
 *    primegen <bits> [<num>]
 *
 *    <bits>   - number of significant bits each prime should have
 *    <num>    - number of primes to generate
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <time.h>

#include "mpi.h"
#include "mplogic.h"
#include "mpprime.h"

#define NUM_TESTS 5  /* Number of Rabin-Miller iterations to test with */

#ifdef DEBUG
#define FPUTC(x,y) fputc(x,y)
#else
#define FPUTC(x,y) 
#endif

int main(int argc, char *argv[])
{
  unsigned char *raw;
  char          *out;
  unsigned long nTries;
  int		rawlen, bits, outlen, ngen, ix, jx;
  int           g_strong = 0;
  mp_int	testval;
  mp_err	res;
  clock_t	start, end;

  /* We'll just use the C library's rand() for now, although this
     won't be good enough for cryptographic purposes */
  if((out = getenv("SEED")) == NULL) {
    srand((unsigned int)time(NULL));
  } else {
    srand((unsigned int)atoi(out));
  }

  if(argc < 2) {
    fprintf(stderr, "Usage: %s <bits> [<count> [strong]]\n", argv[0]);
    return 1;
  }
	
  if((bits = abs(atoi(argv[1]))) < CHAR_BIT) {
    fprintf(stderr, "%s: please request at least %d bits.\n",
	    argv[0], CHAR_BIT);
    return 1;
  }

  /* If optional third argument is given, use that as the number of
     primes to generate; otherwise generate one prime only.
   */
  if(argc < 3) {
    ngen = 1;
  } else {
    ngen = abs(atoi(argv[2]));
  }

  /* If fourth argument is given, and is the word "strong", we'll 
     generate strong (Sophie Germain) primes. 
   */
  if(argc > 3 && strcmp(argv[3], "strong") == 0)
    g_strong = 1;

  /* testval - candidate being tested; nTries - number tried so far */
  if ((res = mp_init(&testval)) != MP_OKAY) {
    fprintf(stderr, "%s: error: %s\n", argv[0], mp_strerror(res));
    return 1;
  }
  
  if(g_strong) {
    printf("Requested %d strong prime value(s) of %d bits.\n", 
	   ngen, bits);
  } else {
    printf("Requested %d prime value(s) of %d bits.\n", ngen, bits);
  }

  rawlen = (bits / CHAR_BIT) + ((bits % CHAR_BIT) ? 1 : 0) + 1;

  if((raw = calloc(rawlen, sizeof(unsigned char))) == NULL) {
    fprintf(stderr, "%s: out of memory, sorry.\n", argv[0]);
    return 1;
  }

  /* This loop is one for each prime we need to generate */
  for(jx = 0; jx < ngen; jx++) {

    raw[0] = 0;  /* sign is positive */

    /*	Pack the initializer with random bytes	*/
    for(ix = 1; ix < rawlen; ix++) 
      raw[ix] = (rand() * rand()) & UCHAR_MAX;

    raw[1] |= 0x80;             /* set high-order bit of test value     */
    raw[rawlen - 1] |= 1;       /* set low-order bit of test value      */

    /* Make an mp_int out of the initializer */
    mp_read_raw(&testval, (char *)raw, rawlen);

    /* Initialize candidate counter */
    nTries = 0;

    start = clock(); /* time generation for this prime */
    do {
      res = mpp_make_prime(&testval, bits, g_strong, &nTries);
      if (res != MP_NO)
	break;
      /* This code works whether digits are 16 or 32 bits */
      res = mp_add_d(&testval, 32 * 1024, &testval);
      res = mp_add_d(&testval, 32 * 1024, &testval);
      FPUTC(',', stderr);
    } while (1);
    end = clock();

    if (res != MP_YES) {
      break;
    }
    FPUTC('\n', stderr);
    puts("The following value is probably prime:");
    outlen = mp_radix_size(&testval, 10);
    out = calloc(outlen, sizeof(unsigned char));
    mp_toradix(&testval, (char *)out, 10);
    printf("10: %s\n", out);
    mp_toradix(&testval, (char *)out, 16);
    printf("16: %s\n\n", out);
    free(out);
    
    printf("Number of candidates tried: %lu\n", nTries);
    printf("This computation took %ld clock ticks (%.2f seconds)\n",
	   (end - start), ((double)(end - start) / CLOCKS_PER_SEC));
    
    FPUTC('\n', stderr);
  } /* end of loop to generate all requested primes */
  
  if(res != MP_OKAY) 
    fprintf(stderr, "%s: error: %s\n", argv[0], mp_strerror(res));

  free(raw);
  mp_clear(&testval);	
  
  return 0;
}