+
+/*
+ * Estimates the group order for a Diffie-Hellman group that has an
+ * attack complexity approximately the same as O(2**bits). Estimate
+ * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3)))
+ */
+
+int
+dh_estimate(int bits)
+{
+
+ if (bits < 64)
+ return (512); /* O(2**63) */
+ if (bits < 128)
+ return (1024); /* O(2**86) */
+ if (bits < 192)
+ return (2048); /* O(2**116) */
+ return (4096); /* O(2**156) */
+}