--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/etc/pprime.c	Mon May 31 18:25:22 2004 +0000
@@ -0,0 +1,396 @@
+/* Generates provable primes
+ *
+ * See http://iahu.ca:8080/papers/pp.pdf for more info.
+ *
+ * Tom St Denis, [email protected], http://tom.iahu.ca
+ */
+#include <time.h>
+#include "tommath.h"
+
+int   n_prime;
+FILE *primes;
+
+/* fast square root */
+static  mp_digit
+i_sqrt (mp_word x)
+{
+  mp_word x1, x2;
+
+  x2 = x;
+  do {
+    x1 = x2;
+    x2 = x1 - ((x1 * x1) - x) / (2 * x1);
+  } while (x1 != x2);
+
+  if (x1 * x1 > x) {
+    --x1;
+  }
+
+  return x1;
+}
+
+
+/* generates a prime digit */
+static void gen_prime (void)
+{
+  mp_digit r, x, y, next;
+  FILE *out;
+
+  out = fopen("pprime.dat", "wb");
+
+  /* write first set of primes */
+  r = 3; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 5; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 7; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 11; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 13; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 17; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 19; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 23; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 29; fwrite(&r, 1, sizeof(mp_digit), out);
+  r = 31; fwrite(&r, 1, sizeof(mp_digit), out);
+
+  /* get square root, since if 'r' is composite its factors must be < than this */
+  y = i_sqrt (r);
+  next = (y + 1) * (y + 1);
+
+  for (;;) {
+  do {
+    r += 2;			/* next candidate */
+    r &= MP_MASK;
+    if (r < 31) break;
+
+    /* update sqrt ? */
+    if (next <= r) {
+      ++y;
+      next = (y + 1) * (y + 1);
+    }
+
+    /* loop if divisible by 3,5,7,11,13,17,19,23,29  */
+    if ((r % 3) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 5) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 7) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 11) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 13) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 17) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 19) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 23) == 0) {
+      x = 0;
+      continue;
+    }
+    if ((r % 29) == 0) {
+      x = 0;
+      continue;
+    }
+
+    /* now check if r is divisible by x + k={1,7,11,13,17,19,23,29} */
+    for (x = 30; x <= y; x += 30) {
+      if ((r % (x + 1)) == 0) {
+	x = 0;
+	break;
+      }
+      if ((r % (x + 7)) == 0) {
+	x = 0;
+	break;
+      }
+      if ((r % (x + 11)) == 0) {
+	x = 0;
+	break;
+      }
+      if ((r % (x + 13)) == 0) {
+	x = 0;
+	break;
+      }
+      if ((r % (x + 17)) == 0) {
+	x = 0;
+	break;
+      }
+      if ((r % (x + 19)) == 0) {
+	x = 0;
+	break;
+      }
+      if ((r % (x + 23)) == 0) {
+	x = 0;
+	break;
+      }
+      if ((r % (x + 29)) == 0) {
+	x = 0;
+	break;
+      }
+    }
+  } while (x == 0);
+  if (r > 31) { fwrite(&r, 1, sizeof(mp_digit), out); printf("%9d\r", r); fflush(stdout); }
+  if (r < 31) break;
+  }
+
+  fclose(out);
+}
+
+void load_tab(void)
+{
+   primes = fopen("pprime.dat", "rb");
+   if (primes == NULL) {
+      gen_prime();
+      primes = fopen("pprime.dat", "rb");
+   }
+   fseek(primes, 0, SEEK_END);
+   n_prime = ftell(primes) / sizeof(mp_digit);
+}
+
+mp_digit prime_digit(void)
+{
+   int n;
+   mp_digit d;
+
+   n = abs(rand()) % n_prime;
+   fseek(primes, n * sizeof(mp_digit), SEEK_SET);
+   fread(&d, 1, sizeof(mp_digit), primes);
+   return d;
+}
+
+
+/* makes a prime of at least k bits */
+int
+pprime (int k, int li, mp_int * p, mp_int * q)
+{
+  mp_int  a, b, c, n, x, y, z, v;
+  int     res, ii;
+  static const mp_digit bases[] = { 2, 3, 5, 7, 11, 13, 17, 19 };
+
+  /* single digit ? */
+  if (k <= (int) DIGIT_BIT) {
+    mp_set (p, prime_digit ());
+    return MP_OKAY;
+  }
+
+  if ((res = mp_init (&c)) != MP_OKAY) {
+    return res;
+  }
+
+  if ((res = mp_init (&v)) != MP_OKAY) {
+    goto __C;
+  }
+
+  /* product of first 50 primes */
+  if ((res =
+       mp_read_radix (&v,
+		      "19078266889580195013601891820992757757219839668357012055907516904309700014933909014729740190",
+		      10)) != MP_OKAY) {
+    goto __V;
+  }
+
+  if ((res = mp_init (&a)) != MP_OKAY) {
+    goto __V;
+  }
+
+  /* set the prime */
+  mp_set (&a, prime_digit ());
+
+  if ((res = mp_init (&b)) != MP_OKAY) {
+    goto __A;
+  }
+
+  if ((res = mp_init (&n)) != MP_OKAY) {
+    goto __B;
+  }
+
+  if ((res = mp_init (&x)) != MP_OKAY) {
+    goto __N;
+  }
+
+  if ((res = mp_init (&y)) != MP_OKAY) {
+    goto __X;
+  }
+
+  if ((res = mp_init (&z)) != MP_OKAY) {
+    goto __Y;
+  }
+
+  /* now loop making the single digit */
+  while (mp_count_bits (&a) < k) {
+    fprintf (stderr, "prime has %4d bits left\r", k - mp_count_bits (&a));
+    fflush (stderr);
+  top:
+    mp_set (&b, prime_digit ());
+
+    /* now compute z = a * b * 2 */
+    if ((res = mp_mul (&a, &b, &z)) != MP_OKAY) {	/* z = a * b */
+      goto __Z;
+    }
+
+    if ((res = mp_copy (&z, &c)) != MP_OKAY) {	/* c = a * b */
+      goto __Z;
+    }
+
+    if ((res = mp_mul_2 (&z, &z)) != MP_OKAY) {	/* z = 2 * a * b */
+      goto __Z;
+    }
+
+    /* n = z + 1 */
+    if ((res = mp_add_d (&z, 1, &n)) != MP_OKAY) {	/* n = z + 1 */
+      goto __Z;
+    }
+
+    /* check (n, v) == 1 */
+    if ((res = mp_gcd (&n, &v, &y)) != MP_OKAY) {	/* y = (n, v) */
+      goto __Z;
+    }
+
+    if (mp_cmp_d (&y, 1) != MP_EQ)
+      goto top;
+
+    /* now try base x=bases[ii]  */
+    for (ii = 0; ii < li; ii++) {
+      mp_set (&x, bases[ii]);
+
+      /* compute x^a mod n */
+      if ((res = mp_exptmod (&x, &a, &n, &y)) != MP_OKAY) {	/* y = x^a mod n */
+	goto __Z;
+      }
+
+      /* if y == 1 loop */
+      if (mp_cmp_d (&y, 1) == MP_EQ)
+	continue;
+
+      /* now x^2a mod n */
+      if ((res = mp_sqrmod (&y, &n, &y)) != MP_OKAY) {	/* y = x^2a mod n */
+	goto __Z;
+      }
+
+      if (mp_cmp_d (&y, 1) == MP_EQ)
+	continue;
+
+      /* compute x^b mod n */
+      if ((res = mp_exptmod (&x, &b, &n, &y)) != MP_OKAY) {	/* y = x^b mod n */
+	goto __Z;
+      }
+
+      /* if y == 1 loop */
+      if (mp_cmp_d (&y, 1) == MP_EQ)
+	continue;
+
+      /* now x^2b mod n */
+      if ((res = mp_sqrmod (&y, &n, &y)) != MP_OKAY) {	/* y = x^2b mod n */
+	goto __Z;
+      }
+
+      if (mp_cmp_d (&y, 1) == MP_EQ)
+	continue;
+
+      /* compute x^c mod n == x^ab mod n */
+      if ((res = mp_exptmod (&x, &c, &n, &y)) != MP_OKAY) {	/* y = x^ab mod n */
+	goto __Z;
+      }
+
+      /* if y == 1 loop */
+      if (mp_cmp_d (&y, 1) == MP_EQ)
+	continue;
+
+      /* now compute (x^c mod n)^2 */
+      if ((res = mp_sqrmod (&y, &n, &y)) != MP_OKAY) {	/* y = x^2ab mod n */
+	goto __Z;
+      }
+
+      /* y should be 1 */
+      if (mp_cmp_d (&y, 1) != MP_EQ)
+	continue;
+      break;
+    }
+
+    /* no bases worked? */
+    if (ii == li)
+      goto top;
+
+{
+   char buf[4096];
+
+   mp_toradix(&n, buf, 10);
+   printf("Certificate of primality for:\n%s\n\n", buf);
+   mp_toradix(&a, buf, 10);
+   printf("A == \n%s\n\n", buf);
+   mp_toradix(&b, buf, 10);
+   printf("B == \n%s\n\nG == %d\n", buf, bases[ii]);
+   printf("----------------------------------------------------------------\n");
+}
+
+    /* a = n */
+    mp_copy (&n, &a);
+  }
+
+  /* get q to be the order of the large prime subgroup */
+  mp_sub_d (&n, 1, q);
+  mp_div_2 (q, q);
+  mp_div (q, &b, q, NULL);
+
+  mp_exch (&n, p);
+
+  res = MP_OKAY;
+__Z:mp_clear (&z);
+__Y:mp_clear (&y);
+__X:mp_clear (&x);
+__N:mp_clear (&n);
+__B:mp_clear (&b);
+__A:mp_clear (&a);
+__V:mp_clear (&v);
+__C:mp_clear (&c);
+  return res;
+}
+
+
+int
+main (void)
+{
+  mp_int  p, q;
+  char    buf[4096];
+  int     k, li;
+  clock_t t1;
+
+  srand (time (NULL));
+  load_tab();
+
+  printf ("Enter # of bits: \n");
+  fgets (buf, sizeof (buf), stdin);
+  sscanf (buf, "%d", &k);
+
+  printf ("Enter number of bases to try (1 to 8):\n");
+  fgets (buf, sizeof (buf), stdin);
+  sscanf (buf, "%d", &li);
+
+
+  mp_init (&p);
+  mp_init (&q);
+
+  t1 = clock ();
+  pprime (k, li, &p, &q);
+  t1 = clock () - t1;
+
+  printf ("\n\nTook %ld ticks, %d bits\n", t1, mp_count_bits (&p));
+
+  mp_toradix (&p, buf, 10);
+  printf ("P == %s\n", buf);
+  mp_toradix (&q, buf, 10);
+  printf ("Q == %s\n", buf);
+
+  return 0;
+}