X-Git-Url: http://andersk.mit.edu/gitweb/gssapi-openssh.git/blobdiff_plain/cdd66111973295c976f1a0bb57f571eba0513757..a7045e2e7435a176522df49a644f13d47b5291af:/openssh/openbsd-compat/bsd-arc4random.c

diff --git a/openssh/openbsd-compat/bsd-arc4random.c b/openssh/openbsd-compat/bsd-arc4random.c
index 5cbb233..7c0f34d 100644
--- a/openssh/openbsd-compat/bsd-arc4random.c
+++ b/openssh/openbsd-compat/bsd-arc4random.c
@@ -34,7 +34,8 @@ RCSID("$Id$");
 static int rc4_ready = 0;
 static RC4_KEY rc4;
 
-unsigned int arc4random(void)
+unsigned int
+arc4random(void)
 {
 	unsigned int r = 0;
 	static int first_time = 1;
@@ -53,16 +54,25 @@ unsigned int arc4random(void)
 	return(r);
 }
 
-void arc4random_stir(void)
+void
+arc4random_stir(void)
 {
 	unsigned char rand_buf[SEED_SIZE];
+	int i;
 
 	memset(&rc4, 0, sizeof(rc4));
 	if (RAND_bytes(rand_buf, sizeof(rand_buf)) <= 0)
 		fatal("Couldn't obtain random bytes (error %ld)",
 		    ERR_get_error());
 	RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);
-	RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf);
+
+	/*
+	 * Discard early keystream, as per recommendations in:
+	 * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
+	 */
+	for(i = 0; i <= 256; i += sizeof(rand_buf))
+		RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf);
+
 	memset(rand_buf, 0, sizeof(rand_buf));
 
 	rc4_ready = REKEY_BYTES;