- markus@cvs.openbsd.org 2001/04/03 19:53:29

[openssh.git] / dh.c

diff --git a/dh.c b/dh.c
index 6c53b0038d0175c7c8ff8be46d6151eba9691f78..03b9fd1b84eaf5ecf554d863ce5a381a932d2f09 100644 (file)
--- a/dh.c
+++ b/dh.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: dh.c,v 1.11 2001/03/29 21:17:39 markus Exp $");
+RCSID("$OpenBSD: dh.c,v 1.12 2001/04/03 19:53:29 markus Exp $");
 
 #include "xmalloc.h"
 
@@ -273,3 +273,22 @@ dh_new_group1(void)
 
        return (dh_new_group_asc(gen, group1));
 }
+
+/*
+ * 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) */
+}