1 files changed, 59 insertions, 0 deletions
diff --git a/libtommath/etc/drprime.c b/libtommath/etc/drprime.c
new file mode 100644
index 0000000..0d0fdb9
--- /dev/null
+++ b/libtommath/etc/drprime.c
@@ -0,0 +1,59 @@
+/* Makes safe primes of a DR nature */
+#include <tommath.h>
+
+int sizes[] = { 1+256/DIGIT_BIT, 1+512/DIGIT_BIT, 1+768/DIGIT_BIT, 1+1024/DIGIT_BIT, 1+2048/DIGIT_BIT, 1+4096/DIGIT_BIT };
+int main(void)
+{
+   int res, x, y;
+   char buf[4096];
+   FILE *out;
+   mp_int a, b;
+   
+   mp_init(&a);
+   mp_init(&b);
+   
+   out = fopen("drprimes.txt", "w");
+   for (x = 0; x < (int)(sizeof(sizes)/sizeof(sizes[0])); x++) {
+   top:
+       printf("Seeking a %d-bit safe prime\n", sizes[x] * DIGIT_BIT);
+       mp_grow(&a, sizes[x]);
+       mp_zero(&a);
+       for (y = 1; y < sizes[x]; y++) {
+           a.dp[y] = MP_MASK;
+       }
+       
+       /* make a DR modulus */
+       a.dp[0] = -1;
+       a.used = sizes[x];
+       
+       /* now loop */
+       res = 0;
+       for (;;) { 
+          a.dp[0] += 4;
+          if (a.dp[0] >= MP_MASK) break;
+          mp_prime_is_prime(&a, 1, &res);
+          if (res == 0) continue;
+          printf("."); fflush(stdout);
+          mp_sub_d(&a, 1, &b);
+          mp_div_2(&b, &b);
+          mp_prime_is_prime(&b, 3, &res);  
+          if (res == 0) continue;
+          mp_prime_is_prime(&a, 3, &res);
+          if (res == 1) break;
+	}
+        
+        if (res != 1) {
+           printf("Error not DR modulus\n"); sizes[x] += 1; goto top;
+        } else {
+           mp_toradix(&a, buf, 10);
+           printf("\n\np == %s\n\n", buf);
+           fprintf(out, "%d-bit prime:\np == %s\n\n", mp_count_bits(&a), buf); fflush(out);
+        }           
+   }
+   fclose(out);
+   
+   mp_clear(&a);
+   mp_clear(&b);
+   
+   return 0;
+}