svn commit: r315225 - in head: lib/libc/gen sys/libkern
Xin LI
delphij at FreeBSD.org
Tue Mar 14 06:00:46 UTC 2017
Author: delphij
Date: Tue Mar 14 06:00:44 2017
New Revision: 315225
URL: https://svnweb.freebsd.org/changeset/base/315225
Log:
Discard first 3072 bytes of RC4 keystream, this is a bandaid
that allows us to work on switching to a more modern PRNG.
Submitted by: Steven Chamberlain <steven pyro eu org>
Approved by: so
Modified:
head/lib/libc/gen/arc4random.c
head/sys/libkern/arc4random.c
Modified: head/lib/libc/gen/arc4random.c
==============================================================================
--- head/lib/libc/gen/arc4random.c Tue Mar 14 02:13:59 2017 (r315224)
+++ head/lib/libc/gen/arc4random.c Tue Mar 14 06:00:44 2017 (r315225)
@@ -160,7 +160,7 @@ arc4_stir(void)
* Discard early keystream, as per recommendations in:
* "(Not So) Random Shuffles of RC4" by Ilya Mironov.
*/
- for (i = 0; i < 1024; i++)
+ for (i = 0; i < 3072; i++)
(void)arc4_getbyte();
arc4_count = 1600000;
}
Modified: head/sys/libkern/arc4random.c
==============================================================================
--- head/sys/libkern/arc4random.c Tue Mar 14 02:13:59 2017 (r315224)
+++ head/sys/libkern/arc4random.c Tue Mar 14 06:00:44 2017 (r315225)
@@ -84,11 +84,11 @@ arc4_randomstir(struct arc4_s* arc4)
/*
* Throw away the first N words of output, as suggested in the
* paper "Weaknesses in the Key Scheduling Algorithm of RC4"
- * by Fluher, Mantin, and Shamir. (N = 256 in our case.)
+ * by Fluher, Mantin, and Shamir. (N = 768 in our case.)
*
* http://dl.acm.org/citation.cfm?id=646557.694759
*/
- for (n = 0; n < 256*4; n++)
+ for (n = 0; n < 768*4; n++)
arc4_randbyte(arc4);
mtx_unlock(&arc4->mtx);
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