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-rw-r--r--libtommath/etc/drprime.c59
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;
+}