Use arc4random_buf() when requesting more than a single word of output

Use arc4random_uniform() when the desired random number upper bound
is not a power of two

ok deraadt@ millert@

22 files changed, 70 insertions, 93 deletions

diff --git a/games/fortune/fortune/fortune.c b/games/fortune/fortune/fortune.c
index 18366533250..798137ca547 100644
--- a/games/fortune/fortune/fortune.c
+++ b/games/fortune/fortune/fortune.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fortune.c,v 1.26 2008/03/17 09:17:56 sobrado Exp $	*/
+/*	$OpenBSD: fortune.c,v 1.27 2008/04/13 00:22:16 djm Exp $	*/
 /*	$NetBSD: fortune.c,v 1.8 1995/03/23 08:28:40 cgd Exp $	*/
 
 /*-
@@ -43,7 +43,7 @@ static char copyright[] =
 #if 0
 static char sccsid[] = "@(#)fortune.c	8.1 (Berkeley) 5/31/93";
 #else
-static char rcsid[] = "$OpenBSD: fortune.c,v 1.26 2008/03/17 09:17:56 sobrado Exp $";
+static char rcsid[] = "$OpenBSD: fortune.c,v 1.27 2008/04/13 00:22:16 djm Exp $";
 #endif
 #endif /* not lint */
 
@@ -909,7 +909,7 @@ get_fort(void)
 	if (File_list->next == NULL || File_list->percent == NO_PROB)
 		fp = File_list;
 	else {
-		choice = arc4random() % 100;
+		choice = arc4random_uniform(100);
 		DPRINTF(1, (stderr, "choice = %d\n", choice));
 		for (fp = File_list; fp->percent != NO_PROB; fp = fp->next)
 			if (choice < fp->percent)
@@ -929,7 +929,7 @@ get_fort(void)
 	else {
 		if (fp->next != NULL) {
 			sum_noprobs(fp);
-			choice = arc4random() % Noprob_tbl.str_numstr;
+			choice = arc4random_uniform(Noprob_tbl.str_numstr);
 			DPRINTF(1, (stderr, "choice = %d (of %d) \n", choice,
 				    Noprob_tbl.str_numstr));
 			while (choice >= fp->tbl.str_numstr) {
@@ -971,7 +971,7 @@ pick_child(FILEDESC *parent)
 	int		choice;
 
 	if (Equal_probs) {
-		choice = arc4random() % parent->num_children;
+		choice = arc4random_uniform(parent->num_children);
 		DPRINTF(1, (stderr, "    choice = %d (of %d)\n",
 			    choice, parent->num_children));
 		for (fp = parent->child; choice--; fp = fp->next)
@@ -981,7 +981,7 @@ pick_child(FILEDESC *parent)
 	}
 	else {
 		get_tbl(parent);
-		choice = arc4random() % parent->tbl.str_numstr;
+		choice = arc4random_uniform(parent->tbl.str_numstr);
 		DPRINTF(1, (stderr, "    choice = %d (of %d)\n",
 			    choice, parent->tbl.str_numstr));
 		for (fp = parent->child; choice >= fp->tbl.str_numstr;
@@ -1065,7 +1065,7 @@ get_pos(FILEDESC *fp)
 #ifdef	OK_TO_WRITE_DISK
 		if ((fd = open(fp->posfile, 0)) < 0 ||
 		    read(fd, &fp->pos, sizeof fp->pos) != sizeof fp->pos)
-			fp->pos = arc4random() % fp->tbl.str_numstr;
+			fp->pos = arc4random_uniform(fp->tbl.str_numstr);
 		else if (ntohl(fp->pos) >= fp->tbl.str_numstr)
 			fp->pos %= fp->tbl.str_numstr;
 		else
@@ -1073,7 +1073,7 @@ get_pos(FILEDESC *fp)
 		if (fd >= 0)
 			(void) close(fd);
 #else
-		fp->pos = arc4random() % fp->tbl.str_numstr;
+		fp->pos = arc4random_uniform(fp->tbl.str_numstr);
 #endif /* OK_TO_WRITE_DISK */
 	}
 	if (++(fp->pos) >= fp->tbl.str_numstr)
diff --git a/games/random/random.c b/games/random/random.c
index e534b46e7cb..cb8ee26af4f 100644
--- a/games/random/random.c
+++ b/games/random/random.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: random.c,v 1.10 2004/07/10 07:26:24 deraadt Exp $	*/
+/*	$OpenBSD: random.c,v 1.11 2008/04/13 00:22:16 djm Exp $	*/
 /*	$NetBSD: random.c,v 1.3 1995/04/22 07:44:05 cgd Exp $	*/
 
 /*
@@ -43,7 +43,7 @@ static char copyright[] =
 #if 0
 static char sccsid[] = "@(#)random.c	8.5 (Berkeley) 4/5/94";
 #else
-static char rcsid[] = "$OpenBSD: random.c,v 1.10 2004/07/10 07:26:24 deraadt Exp $";
+static char rcsid[] = "$OpenBSD: random.c,v 1.11 2008/04/13 00:22:16 djm Exp $";
 #endif
 #endif /* not lint */
 
@@ -105,7 +105,7 @@ main(int argc, char *argv[])
 
 	/* Compute a random exit status between 0 and denom - 1. */
 	if (random_exit)
-		return (arc4random() % (u_int32_t)denom);
+		return (arc4random_uniform(denom));
 
 	/*
 	 * Act as a filter, randomly choosing lines of the standard input
@@ -120,7 +120,7 @@ main(int argc, char *argv[])
 	 * 0 (which has a 1 / denom chance of being true), we select the
 	 * line.
 	 */
-	selected = (int)(arc4random() % (u_int32_t)denom) == 0;
+	selected = arc4random_uniform(denom) == 0;
 	while ((ch = getchar()) != EOF) {
 		if (selected)
 			(void)putchar(ch);
@@ -130,7 +130,7 @@ main(int argc, char *argv[])
 				err(2, "stdout");
 
 			/* Now see if the next line is to be printed. */
-			selected = (int)(arc4random() % (u_int32_t)denom) == 0;
+			selected = arc4random_uniform(denom) == 0;
 		}
 	}
 	if (ferror(stdin))
diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
index 8348b7ede18..c4869527adb 100644
--- a/lib/libc/stdlib/malloc.c
+++ b/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: malloc.c,v 1.88 2008/02/20 18:31:34 otto Exp $	*/
+/*	$OpenBSD: malloc.c,v 1.89 2008/04/13 00:22:16 djm Exp $	*/
 
 /*
  * ----------------------------------------------------------------------------
@@ -1140,7 +1140,7 @@ malloc_bytes(size_t size)
 
 	if (malloc_guard) {
 		/* Walk to a random position. */
-		i = arc4random() % bp->free;
+		i = arc4random_uniform(bp->free);
 		while (i > 0) {
 			u += u;
 			k++;
diff --git a/libexec/ftpd/ftpd.c b/libexec/ftpd/ftpd.c
index 21579c44ab1..3a7c224010f 100644
--- a/libexec/ftpd/ftpd.c
+++ b/libexec/ftpd/ftpd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ftpd.c,v 1.181 2007/09/02 15:19:20 deraadt Exp $	*/
+/*	$OpenBSD: ftpd.c,v 1.182 2008/04/13 00:22:16 djm Exp $	*/
 /*	$NetBSD: ftpd.c,v 1.15 1995/06/03 22:46:47 mycroft Exp $	*/
 
 /*
@@ -70,7 +70,7 @@ static const char copyright[] =
 static const char sccsid[] = "@(#)ftpd.c	8.4 (Berkeley) 4/16/94";
 #else
 static const char rcsid[] =
-    "$OpenBSD: ftpd.c,v 1.181 2007/09/02 15:19:20 deraadt Exp $";
+    "$OpenBSD: ftpd.c,v 1.182 2008/04/13 00:22:16 djm Exp $";
 #endif
 #endif /* not lint */
 
@@ -920,7 +920,7 @@ pass(char *passwd)
 			useconds_t us;
 
 			/* Sleep between 1 and 3 seconds to emulate a crypt. */
-			us = arc4random() % 3000000;
+			us = arc4random_uniform(3000000);
 			usleep(us);
 			if (as != NULL) {
 				auth_close(as);
diff --git a/libexec/identd/parse.c b/libexec/identd/parse.c
index dd4c3e11a8a..768b2ec9f3b 100644
--- a/libexec/identd/parse.c
+++ b/libexec/identd/parse.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.c,v 1.45 2007/09/26 02:50:36 ray Exp $	*/
+/*	$OpenBSD: parse.c,v 1.46 2008/04/13 00:22:17 djm Exp $	*/
 
 /*
  * This program is in the public domain and may be used freely by anyone
@@ -105,9 +105,9 @@ gentoken(char *buf, int len)
 		return;
 	for (p = buf; len > 1; p++, len--) {
 		if (p == buf)
-			*p = token0cnv[arc4random() % (sizeof token0cnv-1)];
+			*p = token0cnv[arc4random_uniform(sizeof(token0cnv)-1)];
 		else
-			*p = tokencnv[arc4random() % (sizeof tokencnv-1)];
+			*p = tokencnv[arc4random_uniform(sizeof(tokencnv)-1)];
 	}
 	*p = '\0';
 }
diff --git a/libexec/tftp-proxy/tftp-proxy.c b/libexec/tftp-proxy/tftp-proxy.c
index 52db0d683c7..d2d2875717a 100644
--- a/libexec/tftp-proxy/tftp-proxy.c
+++ b/libexec/tftp-proxy/tftp-proxy.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tftp-proxy.c,v 1.5 2008/03/24 16:11:00 deraadt Exp $
+/* $OpenBSD: tftp-proxy.c,v 1.6 2008/04/13 00:22:17 djm Exp $
  *
  * Copyright (c) 2005 DLS Internet Services
  * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
@@ -383,8 +383,8 @@ sock_ntop(struct sockaddr *sa)
 u_int16_t
 pick_proxy_port(void)
 {
-	return (IPPORT_HIFIRSTAUTO + (arc4random() %
-	    (IPPORT_HILASTAUTO - IPPORT_HIFIRSTAUTO)));
+	return (IPPORT_HIFIRSTAUTO +
+	    arc4random_uniform(IPPORT_HILASTAUTO - IPPORT_HIFIRSTAUTO));
 }
 
 static void
diff --git a/regress/lib/libc/malloc/malloc0test/malloc0test.c b/regress/lib/libc/malloc/malloc0test/malloc0test.c
index eb00954f928..06ff0996eef 100644
--- a/regress/lib/libc/malloc/malloc0test/malloc0test.c
+++ b/regress/lib/libc/malloc/malloc0test/malloc0test.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: malloc0test.c,v 1.4 2004/08/04 12:02:57 otto Exp $	*/
+/*	$OpenBSD: malloc0test.c,v 1.5 2008/04/13 00:22:17 djm Exp $	*/
 /*
  * Public domain.  2001, Theo de Raadt
  */
@@ -92,7 +92,7 @@ usage:
 		limit = LONG_MAX;
 
 	for (count = 0; count < limit; count++) {
-		size = arc4random() % SIZE;
+		size = arc4random_uniform(SIZE);
 		blob = malloc(size);
 		if (blob == NULL) {
 			fprintf(stderr, "success: out of memory\n");
diff --git a/regress/sys/kern/signal-stress/signal-stress.c b/regress/sys/kern/signal-stress/signal-stress.c
index 9f40e0bb680..61aa23bcd66 100644
--- a/regress/sys/kern/signal-stress/signal-stress.c
+++ b/regress/sys/kern/signal-stress/signal-stress.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: signal-stress.c,v 1.2 2004/08/05 15:06:59 art Exp $	*/
+/*	$OpenBSD: signal-stress.c,v 1.3 2008/04/13 00:22:17 djm Exp $	*/
 /*
  *	Written by Artur Grabowski <art@openbsd.org> 2004 Public Domain.
  */
@@ -140,14 +140,14 @@ main()
 	 * Now all children are ready for action.
 	 * Send the first signals and wait until they all exit.
 	 */
-	kill(pids[arc4random() % nprocs], SIGUSR1);
-	kill(pids[arc4random() % nprocs], SIGUSR2);
+	kill(pids[arc4random_uniform(nprocs)], SIGUSR1);
+	kill(pids[arc4random_uniform(nprocs)], SIGUSR2);
 
 	/*
 	 * The signal game is running, now insert noise in the process.
 	 */
 	for (i = 0; i < nprocs; i++) {
-		pid_t pid = pids[arc4random() % nprocs];
+		pid_t pid = pids[arc4random_uniform(nprocs)];
 		kill(pid, SIGSTOP);
 		wait_stopped(pid);
 		kill(pid, SIGCONT);
diff --git a/regress/sys/sys/tree/rb/rb-test.c b/regress/sys/sys/tree/rb/rb-test.c
index f3be4cc0b68..409cc22393a 100644
--- a/regress/sys/sys/tree/rb/rb-test.c
+++ b/regress/sys/sys/tree/rb/rb-test.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rb-test.c,v 1.3 2003/07/31 21:48:10 deraadt Exp $	*/
+/*	$OpenBSD: rb-test.c,v 1.4 2008/04/13 00:22:17 djm Exp $	*/
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * All rights reserved.
@@ -67,7 +67,7 @@ main(int argc, char **argv)
 		tmp = malloc(sizeof(struct node));
 		if (tmp == NULL) err(1, "malloc");
 		do {
-			tmp->key = arc4random() % (MAX-MIN);
+			tmp->key = arc4random_uniform(MAX-MIN);
 			tmp->key += MIN;
 		} while (RB_FIND(tree, &root, tmp) != NULL);
 		if (i == 0)
diff --git a/regress/sys/sys/tree/splay/splay-test.c b/regress/sys/sys/tree/splay/splay-test.c
index 29718302b49..56084a0c71e 100644
--- a/regress/sys/sys/tree/splay/splay-test.c
+++ b/regress/sys/sys/tree/splay/splay-test.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: splay-test.c,v 1.3 2003/07/31 21:48:10 deraadt Exp $	*/
+/*	$OpenBSD: splay-test.c,v 1.4 2008/04/13 00:22:17 djm Exp $	*/
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * All rights reserved.
@@ -67,7 +67,7 @@ main(int argc, char **argv)
 		tmp = malloc(sizeof(struct node));
 		if (tmp == NULL) err(1, "malloc");
 		do {
-			tmp->key = arc4random() % (MAX-MIN);
+			tmp->key = arc4random_uniform(MAX-MIN);
 			tmp->key += MIN;
 		} while (SPLAY_FIND(tree, &root, tmp) != NULL);
 		if (i == 0)
diff --git a/sbin/routed/main.c b/sbin/routed/main.c
index e57c8960ec4..e5b002c3ece 100644
--- a/sbin/routed/main.c
+++ b/sbin/routed/main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: main.c,v 1.19 2005/03/23 18:06:07 jmc Exp $	*/
+/*	$OpenBSD: main.c,v 1.20 2008/04/13 00:22:17 djm Exp $	*/
 
 /*
  * Copyright (c) 1983, 1988, 1993
@@ -35,7 +35,7 @@ char copyright[] =
 #if !defined(lint)
 static char sccsid[] = "@(#)main.c	8.1 (Berkeley) 6/5/93";
 #else
-static char rcsid[] = "$OpenBSD: main.c,v 1.19 2005/03/23 18:06:07 jmc Exp $";
+static char rcsid[] = "$OpenBSD: main.c,v 1.20 2008/04/13 00:22:17 djm Exp $";
 #endif
 
 #include "defs.h"
@@ -766,8 +766,8 @@ intvl_random(struct timeval *tp,	/* put value here */
 {
 	tp->tv_sec = (time_t)(hi == lo
 			      ? lo
-			      : (lo + arc4random() % ((1 + hi - lo))));
-	tp->tv_usec = arc4random() % 1000000;
+			      : (lo + arc4random_uniform(1 + hi - lo)));
+	tp->tv_usec = arc4random_uniform(1000000);
 }
 
 
diff --git a/usr.bin/awk/run.c b/usr.bin/awk/run.c
index cdce6a398e3..3dccfff73a1 100644
--- a/usr.bin/awk/run.c
+++ b/usr.bin/awk/run.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: run.c,v 1.27 2008/02/27 17:19:34 deraadt Exp $	*/
+/*	$OpenBSD: run.c,v 1.28 2008/04/13 00:22:17 djm Exp $	*/
 /****************************************************************
 Copyright (C) Lucent Technologies 1997
 All Rights Reserved
@@ -1515,7 +1515,7 @@ Cell *bltin(Node **a, int n)	/* builtin functions. a[0] is type, a[1] is arg lis
 		break;
 	case FRAND:
 		if (use_arc4)
-			u = (Awkfloat) (arc4random() % RAND_MAX) / RAND_MAX;
+			u = (Awkfloat)arc4random() / 0xffffffff;
 		else
 			u = (Awkfloat) (random() % RAND_MAX) / RAND_MAX;
 		break;
diff --git a/usr.bin/calendar/day.c b/usr.bin/calendar/day.c
index dc97bfb8bc1..1a0f5953c3b 100644
--- a/usr.bin/calendar/day.c
+++ b/usr.bin/calendar/day.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: day.c,v 1.20 2005/11/16 16:45:11 deraadt Exp $	*/
+/*	$OpenBSD: day.c,v 1.21 2008/04/13 00:22:17 djm Exp $	*/
 
 /*
  * Copyright (c) 1989, 1993, 1994
@@ -39,7 +39,7 @@ static const char copyright[] =
 #if 0
 static const char sccsid[] = "@(#)calendar.c  8.3 (Berkeley) 3/25/94";
 #else
-static const char rcsid[] = "$OpenBSD: day.c,v 1.20 2005/11/16 16:45:11 deraadt Exp $";
+static const char rcsid[] = "$OpenBSD: day.c,v 1.21 2008/04/13 00:22:17 djm Exp $";
 #endif
 #endif /* not lint */
 
@@ -301,7 +301,7 @@ isnow(char *endp, int bodun)
 
 	/* adjust bodun rate */
 	if (bodun && !bodun_always)
-		bodun = !(arc4random() % 3);
+		bodun = !arc4random_uniform(3);
 		
 	/* Easter or Easter depending days */
 	if (flags & F_SPECIAL)
diff --git a/usr.bin/mg/theo.c b/usr.bin/mg/theo.c
index 0d452ee1999..85e5357f3d1 100644
--- a/usr.bin/mg/theo.c
+++ b/usr.bin/mg/theo.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: theo.c,v 1.101 2007/08/28 17:57:16 jasper Exp $	*/
+/*	$OpenBSD: theo.c,v 1.102 2008/04/13 00:22:17 djm Exp $	*/
 /*
  * Copyright (c) 2002 Artur Grabowski <art@openbsd.org>
  * All rights reserved.
@@ -158,7 +158,7 @@ theo_analyze(int f, int n)
 	const char	*str;
 	int		 len;
 
-	str = talk[arc4random() % ntalk];
+	str = talk[arc4random_uniform(ntalk)];
 	len = strlen(str);
 
 	newline(FFRAND, 2);
diff --git a/usr.bin/ssh/dh.c b/usr.bin/ssh/dh.c
index c658f745ef0..db8f0166df2 100644
--- a/usr.bin/ssh/dh.c
+++ b/usr.bin/ssh/dh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dh.c,v 1.45 2007/09/27 00:15:57 ray Exp $ */
+/* $OpenBSD: dh.c,v 1.46 2008/04/13 00:22:17 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  *
@@ -150,7 +150,7 @@ choose_dh(int min, int wantbits, int max)
 	}
 
 	linenum = 0;
-	which = arc4random() % bestcount;
+	which = arc4random_uniform(bestcount);
 	while (fgets(line, sizeof(line), f)) {
 		if (!parse_prime(linenum, line, &dhg))
 			continue;
diff --git a/usr.bin/ssh/sshd.c b/usr.bin/ssh/sshd.c
index 1a032d8a65a..2e52fff7c9d 100644
--- a/usr.bin/ssh/sshd.c
+++ b/usr.bin/ssh/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.355 2008/02/14 13:10:31 mbalmer Exp $ */
+/* $OpenBSD: sshd.c,v 1.356 2008/04/13 00:22:17 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -348,9 +348,6 @@ grace_alarm_handler(int sig)
 static void
 generate_ephemeral_server_key(void)
 {
-	u_int32_t rnd = 0;
-	int i;
-
 	verbose("Generating %s%d bit RSA key.",
 	    sensitive_data.server_key ? "new " : "", options.server_key_bits);
 	if (sensitive_data.server_key != NULL)
@@ -359,12 +356,7 @@ generate_ephemeral_server_key(void)
 	    options.server_key_bits);
 	verbose("RSA key generation complete.");
 
-	for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
-		if (i % 4 == 0)
-			rnd = arc4random();
-		sensitive_data.ssh1_cookie[i] = rnd & 0xff;
-		rnd >>= 8;
-	}
+	arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
 	arc4random_stir();
 }
 
@@ -566,14 +558,12 @@ privsep_preauth_child(void)
 	u_int32_t rnd[256];
 	gid_t gidset[1];
 	struct passwd *pw;
-	u_int i;
 
 	/* Enable challenge-response authentication for privilege separation */
 	privsep_challenge_enable();
 
 	arc4random_stir();
-	for (i = 0; i < 256; i++)
-		rnd[i] = arc4random();
+	arc4random_buf(rnd, sizeof(rnd));
 	RAND_seed(rnd, sizeof(rnd));
 
 	/* Demote the private keys to public keys. */
@@ -653,7 +643,6 @@ static void
 privsep_postauth(Authctxt *authctxt)
 {
 	u_int32_t rnd[256];
-	u_int i;
 
 	if (authctxt->pw->pw_uid == 0 || options.use_login) {
 		/* File descriptor passing is broken or root login */
@@ -683,8 +672,7 @@ privsep_postauth(Authctxt *authctxt)
 	demote_sensitive_data();
 
 	arc4random_stir();
-	for (i = 0; i < 256; i++)
-		rnd[i] = arc4random();
+	arc4random_buf(rnd, sizeof(rnd));
 	RAND_seed(rnd, sizeof(rnd));
 
 	/* Drop privileges */
@@ -786,7 +774,7 @@ drop_connection(int startups)
 	p *= startups - options.max_startups_begin;
 	p /= options.max_startups - options.max_startups_begin;
 	p += options.max_startups_rate;
-	r = arc4random() % 100;
+	r = arc4random_uniform(100);
 
 	debug("drop_connection: p %d, r %d", p, r);
 	return (r < p) ? 1 : 0;
@@ -1808,7 +1796,6 @@ do_ssh1_kex(void)
 	u_char session_key[SSH_SESSION_KEY_LENGTH];
 	u_char cookie[8];
 	u_int cipher_type, auth_mask, protocol_flags;
-	u_int32_t rnd = 0;
 
 	/*
 	 * Generate check bytes that the client must send back in the user
@@ -1819,12 +1806,7 @@ do_ssh1_kex(void)
 	 * cookie.  This only affects rhosts authentication, and this is one
 	 * of the reasons why it is inherently insecure.
 	 */
-	for (i = 0; i < 8; i++) {
-		if (i % 4 == 0)
-			rnd = arc4random();
-		cookie[i] = rnd & 0xff;
-		rnd >>= 8;
-	}
+	arc4random_buf(cookie, sizeof(cookie));
 
 	/*
 	 * Send our public key.  We include in the packet 64 bits of random
diff --git a/usr.sbin/ftp-proxy/ftp-proxy.c b/usr.sbin/ftp-proxy/ftp-proxy.c
index 1a3bdf55fbd..cf697b56614 100644
--- a/usr.sbin/ftp-proxy/ftp-proxy.c
+++ b/usr.sbin/ftp-proxy/ftp-proxy.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ftp-proxy.c,v 1.16 2008/02/26 18:52:53 henning Exp $ */
+/*	$OpenBSD: ftp-proxy.c,v 1.17 2008/04/13 00:22:17 djm Exp $ */
 
 /*
  * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
@@ -834,8 +834,8 @@ u_int16_t
 pick_proxy_port(void)
 {
 	/* Random should be good enough for avoiding port collisions. */
-	return (IPPORT_HIFIRSTAUTO + (arc4random() %
-	    (IPPORT_HILASTAUTO - IPPORT_HIFIRSTAUTO)));
+	return (IPPORT_HIFIRSTAUTO +
+	    arc4random_uniform(IPPORT_HILASTAUTO - IPPORT_HIFIRSTAUTO));
 }
 
 void
diff --git a/usr.sbin/httpd/src/modules/standard/mod_rewrite.c b/usr.sbin/httpd/src/modules/standard/mod_rewrite.c
index a7cdffea2ce..2609cc03729 100644
--- a/usr.sbin/httpd/src/modules/standard/mod_rewrite.c
+++ b/usr.sbin/httpd/src/modules/standard/mod_rewrite.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mod_rewrite.c,v 1.25 2006/07/28 13:52:30 henning Exp $ */
+/*	$OpenBSD: mod_rewrite.c,v 1.26 2008/04/13 00:22:17 djm Exp $ */
 
 /* ====================================================================
  * The Apache Software License, Version 1.1
@@ -3171,13 +3171,7 @@ static char *rewrite_mapfunc_unescape(request_rec *r, char *key)
 
 static int rewrite_rand(int l, int h)
 {
-    /* Get [0,1) and then scale to the appropriate range. Note that using
-     * a floating point value ensures that we use all bits of the arc4random()
-     * result. Doing an integer modulus would yield a non-uniformly distibuted
-     * result, because MAX_UINT may not be divisble by the size of the
-     * interval.
-     */
-    return (int)(arc4random() / ((double)0xffffffffU + 1) * (h - l + 1) + l);
+    return arc4random_uniform(1 + h - l) + l;
 }
 
 static char *select_random_value_part(request_rec *r, char *value)
diff --git a/usr.sbin/ntpd/ntp.c b/usr.sbin/ntpd/ntp.c
index 28234875813..7026a9ba548 100644
--- a/usr.sbin/ntpd/ntp.c
+++ b/usr.sbin/ntpd/ntp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.103 2008/01/28 11:45:59 mpf Exp $ */
+/*	$OpenBSD: ntp.c,v 1.104 2008/04/13 00:22:17 djm Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -659,7 +659,7 @@ scale_interval(time_t requested)
 	time_t interval, r;
 
 	interval = requested * conf->scale;
-	r = arc4random() % MAX(5, interval / 10);
+	r = arc4random_uniform(MAX(5, interval / 10));
 	return (interval + r);
 }
 
@@ -669,7 +669,7 @@ error_interval(void)
 	time_t interval, r;
 
 	interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN;
-	r = arc4random() % (interval / 10);
+	r = arc4random_uniform(interval / 10);
 	return (interval + r);
 }
 
diff --git a/usr.sbin/ripd/message.c b/usr.sbin/ripd/message.c
index 091d162d640..02060cf3105 100644
--- a/usr.sbin/ripd/message.c
+++ b/usr.sbin/ripd/message.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: message.c,v 1.9 2007/10/24 20:52:50 claudio Exp $ */
+/*	$OpenBSD: message.c,v 1.10 2008/04/13 00:22:17 djm Exp $ */
 
 /*
  * Copyright (c) 2006 Michele Marchetto <mydecay@openbeer.it>
@@ -47,7 +47,7 @@ report_timer(int fd, short event, void *arg)
 
 	/* restart report timer */
 	timerclear(&tv);
-	tv.tv_sec = KEEPALIVE + arc4random() % OFFSET;
+	tv.tv_sec = KEEPALIVE + arc4random_uniform(OFFSET);
 	evtimer_add(&oeconf->report_timer, &tv);
 }
 
@@ -57,7 +57,7 @@ start_report_timer(void)
 	struct timeval	 tv;
 
 	timerclear(&tv);
-	tv.tv_sec = KEEPALIVE + arc4random() % OFFSET;
+	tv.tv_sec = KEEPALIVE + arc4random_uniform(OFFSET);
 	return (evtimer_add(&oeconf->report_timer, &tv));
 }
 
diff --git a/usr.sbin/rtadvd/rtadvd.c b/usr.sbin/rtadvd/rtadvd.c
index fa597f56df4..b258ca92fad 100644
--- a/usr.sbin/rtadvd/rtadvd.c
+++ b/usr.sbin/rtadvd/rtadvd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtadvd.c,v 1.30 2008/03/24 16:11:05 deraadt Exp $	*/
+/*	$OpenBSD: rtadvd.c,v 1.31 2008/04/13 00:22:17 djm Exp $	*/
 /*	$KAME: rtadvd.c,v 1.66 2002/05/29 14:18:36 itojun Exp $	*/
 
 /*
@@ -802,7 +802,7 @@ rs_input(int len, struct nd_router_solicit *rs,
 		 * delay and send the advertisement at the
 		 * already-scheduled time. RFC-2461 6.2.6
 		 */
-		delay = arc4random() % MAX_RA_DELAY_TIME;
+		delay = arc4random_uniform(MAX_RA_DELAY_TIME);
 		interval.tv_sec = 0;
 		interval.tv_usec = delay;
 		rest = rtadvd_timer_rest(ra->timer);
@@ -1568,7 +1568,7 @@ ra_timer_update(void *data, struct timeval *tm)
 	 * MaxRtrAdvInterval (RFC2461 6.2.4).
 	 */
 	interval = rai->mininterval; 
-	interval += arc4random() % (rai->maxinterval - rai->mininterval);
+	interval += arc4random_uniform(rai->maxinterval - rai->mininterval);
 
 	/*
 	 * For the first few advertisements (up to
diff --git a/usr.sbin/rtsold/rtsold.c b/usr.sbin/rtsold/rtsold.c
index 4db48bfcdb6..a711cd27741 100644
--- a/usr.sbin/rtsold/rtsold.c
+++ b/usr.sbin/rtsold/rtsold.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtsold.c,v 1.40 2008/01/05 17:03:09 chl Exp $	*/
+/*	$OpenBSD: rtsold.c,v 1.41 2008/04/13 00:22:17 djm Exp $	*/
 /*	$KAME: rtsold.c,v 1.75 2004/01/03 00:00:07 itojun Exp $	*/
 
 /*
@@ -577,7 +577,8 @@ rtsol_timer_update(struct ifinfo *ifinfo)
 			ifinfo->timer = tm_max;	/* stop timer(valid?) */
 		break;
 	case IFS_DELAY:
-		interval = arc4random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
+		interval = arc4random_uniform(MAX_RTR_SOLICITATION_DELAY *
+		    MILLION);
 		ifinfo->timer.tv_sec = interval / MILLION;
 		ifinfo->timer.tv_usec = interval % MILLION;
 		break;