From 75d4ae826b5756bc949de18c3fcb5596d31e5367 Mon Sep 17 00:00:00 2001
From: deraadt <>
Date: Mon, 8 Dec 2014 21:45:20 +0000
Subject: [PATCH] Change rand(), random(), drand48(), lrand48(), mrand48(), and
 srand48() to returning strong random by default, source from arc4random(3).
 Parameters to the seeding functions are ignored, and the subsystems remain in
 strong random mode.  If you wish the standardized deterministic mode, call
 srand_deterministic(), srandom_determistic(), srand48_deterministic(),
 seed48_deterministic() or lcong48_deterministic() instead. The re-entrant
 functions rand_r(), erand48(), nrand48(), jrand48() are unaffected by this
 change and remain in deterministic mode (for now).

Verified as a good roadmap forward by auditing 8800 pieces of software.
Roughly 60 pieces of software will need adaptation to request the
deterministic mode.

Violates POSIX and C89, which violate best practice in this century.
ok guenther tedu millert
---
 src/include/stdlib.h             |   7 +-
 src/lib/libc/stdlib/Makefile.inc |  10 +--
 src/lib/libc/stdlib/drand48.c    |  10 ++-
 src/lib/libc/stdlib/lcong48.c    |  10 ++-
 src/lib/libc/stdlib/lrand48.c    |   4 +-
 src/lib/libc/stdlib/mrand48.c    |   4 +-
 src/lib/libc/stdlib/rand.3       |  76 +++++++++++++--------
 src/lib/libc/stdlib/rand.c       |  15 +++--
 src/lib/libc/stdlib/rand48.3     | 110 +++++++++++++++++++++++--------
 src/lib/libc/stdlib/rand48.h     |   3 +-
 src/lib/libc/stdlib/random.3     | 110 ++++++++++++++++---------------
 src/lib/libc/stdlib/random.c     |  49 ++++----------
 src/lib/libc/stdlib/seed48.c     |  13 +++-
 src/lib/libc/stdlib/srand48.c    |  12 +++-
 14 files changed, 273 insertions(+), 160 deletions(-)

diff --git a/src/include/stdlib.h b/src/include/stdlib.h
index 1f8e4a35..d048e704 100644
--- a/src/include/stdlib.h
+++ b/src/include/stdlib.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: stdlib.h,v 1.61 2014/12/08 20:39:56 tedu Exp $	*/
+/*	$OpenBSD: stdlib.h,v 1.62 2014/12/08 21:45:19 deraadt Exp $	*/
 /*	$NetBSD: stdlib.h,v 1.25 1995/12/27 21:19:08 jtc Exp $	*/
 
 /*-
@@ -131,6 +131,7 @@ void	 qsort(void *, size_t, size_t, int (*)(const void *, const void *));
 int	 rand(void);
 void	*realloc(void *, size_t);
 void	 srand(unsigned);
+void	 srand_deterministic(unsigned);
 double	 strtod(const char *, char **);
 float	 strtof(const char *, char **);
 long	 strtol(const char *, char **, int);
@@ -159,11 +160,14 @@ double	 drand48(void);
 double	 erand48(unsigned short[3]);
 long	 jrand48(unsigned short[3]);
 void	 lcong48(unsigned short[7]);
+void	 lcong48_deterministic(unsigned short[7]);
 long	 lrand48(void);
 long	 mrand48(void);
 long	 nrand48(unsigned short[3]);
 unsigned short *seed48(unsigned short[3]);
+unsigned short *seed48_deterministic(unsigned short[3]);
 void	 srand48(long);
+void	 srand48_deterministic(long);
 
 int	 putenv(char *);
 #endif
@@ -190,6 +194,7 @@ char	*initstate(unsigned int, char *, size_t)
 long	 random(void);
 char	*setstate(char *);
 void	 srandom(unsigned int);
+void	 srandom_deterministic(unsigned int);
 
 char	*realpath(const char *, char *)
 		__attribute__((__bounded__ (__minbytes__,2,1024)));
diff --git a/src/lib/libc/stdlib/Makefile.inc b/src/lib/libc/stdlib/Makefile.inc
index 3a13d9ff..3e99fe11 100644
--- a/src/lib/libc/stdlib/Makefile.inc
+++ b/src/lib/libc/stdlib/Makefile.inc
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile.inc,v 1.56 2014/12/08 20:39:16 tedu Exp $
+#	$OpenBSD: Makefile.inc,v 1.57 2014/12/08 21:45:20 deraadt Exp $
 
 # stdlib sources
 .PATH: ${LIBCSRCDIR}/arch/${MACHINE_CPU}/stdlib ${LIBCSRCDIR}/stdlib
@@ -43,12 +43,14 @@ MLINKS+=malloc.3 free.3 malloc.3 realloc.3 malloc.3 calloc.3
 MLINKS+=malloc.3 reallocarray.3
 MLINKS+=qsort.3 heapsort.3 qsort.3 mergesort.3
 MLINKS+=radixsort.3 sradixsort.3
-MLINKS+=rand.3 srand.3 rand.3 rand_r.3
+MLINKS+=rand.3 srand.3 rand.3 rand_r.3 rand.3 srand_deterministic.3
 MLINKS+=random.3 initstate.3 random.3 setstate.3
-MLINKS+=random.3 srandom.3 random.3 srandomdev.3
+MLINKS+=random.3 srandom.3 random.3 srandomdev.3 random.3 srandom_deterministic.3
 MLINKS+=rand48.3 drand48.3 rand48.3 erand48.3 rand48.3 lrand48.3
 MLINKS+=rand48.3 mrand48.3 rand48.3 nrand48.3 rand48.3 jrand48.3
-MLINKS+=rand48.3 srand48.3 rand48.3 seed48.3 rand48.3 lcong48.3
+MLINKS+=rand48.3 srand48.3 rand48.3 srand48_deterministic.3
+MLINKS+=rand48.3 seed48.3 rand48.3 seed48_deterministic.3
+MLINKS+=rand48.3 lcong48.3 rand48.3 lcong48_deterministic.3
 MLINKS+=ptsname.3 grantpt.3 ptsname.3 unlockpt.3
 MLINKS+=strtod.3 strtof.3 strtod.3 strtold.3
 MLINKS+=strtol.3 strtoll.3 strtol.3 strtoq.3 strtol.3 strtoimax.3
diff --git a/src/lib/libc/stdlib/drand48.c b/src/lib/libc/stdlib/drand48.c
index b6c046c8..bbeedf8a 100644
--- a/src/lib/libc/stdlib/drand48.c
+++ b/src/lib/libc/stdlib/drand48.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: drand48.c,v 1.3 2005/08/08 08:05:36 espie Exp $ */
+/*	$OpenBSD: drand48.c,v 1.4 2014/12/08 21:45:20 deraadt Exp $ */
 /*
  * Copyright (c) 1993 Martin Birgmeier
  * All rights reserved.
@@ -19,5 +19,13 @@ extern unsigned short __rand48_seed[3];
 double
 drand48(void)
 {
+	if (__rand48_deterministic == 0) {
+		short rseed[3];
+
+		arc4random_buf(rseed, sizeof rseed);
+		return ldexp((double) rseed[0], -48) +
+		       ldexp((double) rseed[1], -32) +
+		       ldexp((double) rseed[2], -16);
+	}
 	return erand48(__rand48_seed);
 }
diff --git a/src/lib/libc/stdlib/lcong48.c b/src/lib/libc/stdlib/lcong48.c
index 2cf5c271..09726efb 100644
--- a/src/lib/libc/stdlib/lcong48.c
+++ b/src/lib/libc/stdlib/lcong48.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: lcong48.c,v 1.3 2005/08/08 08:05:36 espie Exp $ */
+/*	$OpenBSD: lcong48.c,v 1.4 2014/12/08 21:45:20 deraadt Exp $ */
 /*
  * Copyright (c) 1993 Martin Birgmeier
  * All rights reserved.
@@ -21,6 +21,14 @@ extern unsigned short __rand48_add;
 void
 lcong48(unsigned short p[7])
 {
+	lcong48_deterministic(p);
+	__rand48_deterministic = 0;
+}
+
+void
+lcong48_deterministic(unsigned short p[7])
+{
+	__rand48_deterministic = 1;
 	__rand48_seed[0] = p[0];
 	__rand48_seed[1] = p[1];
 	__rand48_seed[2] = p[2];
diff --git a/src/lib/libc/stdlib/lrand48.c b/src/lib/libc/stdlib/lrand48.c
index 21beb858..22508594 100644
--- a/src/lib/libc/stdlib/lrand48.c
+++ b/src/lib/libc/stdlib/lrand48.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: lrand48.c,v 1.3 2005/08/08 08:05:36 espie Exp $ */
+/*	$OpenBSD: lrand48.c,v 1.4 2014/12/08 21:45:20 deraadt Exp $ */
 /*
  * Copyright (c) 1993 Martin Birgmeier
  * All rights reserved.
@@ -19,6 +19,8 @@ extern unsigned short __rand48_seed[3];
 long
 lrand48(void)
 {
+	if (__rand48_deterministic == 0)
+		return arc4random() & 0x7fffffff;
 	__dorand48(__rand48_seed);
 	return ((long) __rand48_seed[2] << 15) + ((long) __rand48_seed[1] >> 1);
 }
diff --git a/src/lib/libc/stdlib/mrand48.c b/src/lib/libc/stdlib/mrand48.c
index 977264ab..7bfccbbf 100644
--- a/src/lib/libc/stdlib/mrand48.c
+++ b/src/lib/libc/stdlib/mrand48.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mrand48.c,v 1.3 2005/08/08 08:05:37 espie Exp $ */
+/*	$OpenBSD: mrand48.c,v 1.4 2014/12/08 21:45:20 deraadt Exp $ */
 /*
  * Copyright (c) 1993 Martin Birgmeier
  * All rights reserved.
@@ -19,6 +19,8 @@ extern unsigned short __rand48_seed[3];
 long
 mrand48(void)
 {
+	if (__rand48_deterministic == 0)
+		return arc4random();
 	__dorand48(__rand48_seed);
 	return ((long) __rand48_seed[2] << 16) + (long) __rand48_seed[1];
 }
diff --git a/src/lib/libc/stdlib/rand.3 b/src/lib/libc/stdlib/rand.3
index 5d4bfe7a..c760161b 100644
--- a/src/lib/libc/stdlib/rand.3
+++ b/src/lib/libc/stdlib/rand.3
@@ -29,52 +29,65 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: rand.3,v 1.17 2014/11/25 17:41:12 millert Exp $
+.\"	$OpenBSD: rand.3,v 1.18 2014/12/08 21:45:20 deraadt Exp $
 .\"
-.Dd $Mdocdate: November 25 2014 $
+.Dd $Mdocdate: December 8 2014 $
 .Dt RAND 3
 .Os
 .Sh NAME
 .Nm rand ,
 .Nm rand_r ,
-.Nm srand
+.Nm srand ,
+.Nm srand_deterministic
 .Nd bad pseudo-random number generator
 .Sh SYNOPSIS
 .In stdlib.h
 .Ft void
 .Fn srand "unsigned int seed"
+.Ft void
+.Fn srand_deterministic "unsigned int seed"
 .Ft int
 .Fn rand void
 .Ft int
 .Fn rand_r "unsigned int *seed"
 .Sh DESCRIPTION
 .Bf -symbolic
-These interfaces are obsoleted by
-.Xr random 3 ,
-which is also unsafe.
-Consider using
-.Xr arc4random 3 .
+Standards insist that this interface return deterministic results.
+Unsafe usage is very common, so
+.Ox
+changed the subsystem to return non-deterministic results by default.
 .Ef
 .Pp
-The
+To satisfy portable code,
+.Fn srand
+may be called to initialize the subsystem.
+In
+.Ox
+the
+.Ar seed
+variable is ignored, and strong random number results will be provided from
+.Xr arc4random 3.
+In other systems, the
+.Ar seed
+variable primes a simplistic deterministic algorithm.
+.Pp
+If the standardized behavior is required
+.Fn srand_deterministic
+can be substituted for
+.Fn srand ,
+then subsequent
 .Fn rand
-function computes a sequence of pseudo-random integers in the range
-of 0 to
-.Dv RAND_MAX
-(as defined by the header file
-.In stdlib.h ) .
+calls will return results using the deterministic algorithm.
 .Pp
 The
-.Fn srand
-function sets its argument as the seed for a new sequence of
-pseudo-random numbers to be returned by
-.Fn rand .
-These sequences are repeatable by calling
-.Fn srand
-with the same seed value.
-.Pp
-If no seed value is provided, the functions are automatically
-seeded with a value of 1.
+.Fn rand
+function returns a result in the range of 0 to
+.Dv RAND_MAX .
+By default, this result comes from
+.Xr arc4random 3 .
+If
+.Fn srand_deterministic
+was called, the result will be computed using the deterministic algorithm.
 .Pp
 The
 .Fn rand_r
@@ -83,6 +96,7 @@ is a thread-safe version of
 Storage for the seed must be provided through the
 .Fa seed
 argument, and needs to have been initialized by the caller.
+It always operates using the deterministic algorithm.
 .Sh SEE ALSO
 .Xr arc4random 3 ,
 .Xr rand48 3 ,
@@ -90,15 +104,23 @@ argument, and needs to have been initialized by the caller.
 .Sh STANDARDS
 The
 .Fn rand
-and
-.Fn srand
-functions conform to
+function conforms to
 .St -ansiC .
 .Pp
 The
 .Fn rand_r
 function conforms to
 .St -p1003.1-2008 .
+.Pp
+The
+.Fn srand
+function does not conform to
+.St -ansiC ,
+intentionally.
+.Pp
+The
+.Fn srand_deterministic
+function is an OpenBSD extension.
 .Sh HISTORY
 The functions
 .Fn rand
diff --git a/src/lib/libc/stdlib/rand.c b/src/lib/libc/stdlib/rand.c
index 6860dd4f..618559fd 100644
--- a/src/lib/libc/stdlib/rand.c
+++ b/src/lib/libc/stdlib/rand.c
@@ -30,6 +30,7 @@
 #include <sys/types.h>
 #include <stdlib.h>
 
+static int rand_deterministic;
 static u_int next = 1;
 
 int
@@ -47,6 +48,8 @@ __warn_references(rand_r,
 int
 rand(void)
 {
+	if (rand_deterministic)
+		return (arc4random() % ((u_int)RAND_MAX + 1));
 	return (rand_r(&next));
 }
 
@@ -58,10 +61,12 @@ __warn_references(rand,
 void
 srand(u_int seed)
 {
-	next = seed;
+	rand_deterministic = 0;
 }
 
-#if defined(APIWARN)
-__warn_references(srand,
-    "warning: srand() seed choices are invariably poor");
-#endif
+void
+srand_deterministic(u_int seed)
+{
+	rand_deterministic = 1;
+	next = seed;
+}
diff --git a/src/lib/libc/stdlib/rand48.3 b/src/lib/libc/stdlib/rand48.3
index a4473185..dce8c0dd 100644
--- a/src/lib/libc/stdlib/rand48.3
+++ b/src/lib/libc/stdlib/rand48.3
@@ -9,9 +9,9 @@
 .\" of any kind. I shall in no event be liable for anything that happens
 .\" to anyone/anything when using this software.
 .\"
-.\"	$OpenBSD: rand48.3,v 1.16 2014/11/25 17:26:34 millert Exp $
+.\"	$OpenBSD: rand48.3,v 1.17 2014/12/08 21:45:20 deraadt Exp $
 .\"
-.Dd $Mdocdate: November 25 2014 $
+.Dd $Mdocdate: December 8 2014 $
 .Dt RAND48 3
 .Os
 .Sh NAME
@@ -22,8 +22,11 @@
 .Nm mrand48 ,
 .Nm jrand48 ,
 .Nm srand48 ,
+.Nm srand48_deterministic ,
 .Nm seed48 ,
+.Nm seed48_deterministic ,
 .Nm lcong48
+.Nm lcong48_deterministic
 .Nd pseudo-random number generators and initialization routines
 .Sh SYNOPSIS
 .In stdlib.h
@@ -41,31 +44,56 @@
 .Fn jrand48 "unsigned short xseed[3]"
 .Ft void
 .Fn srand48 "long seed"
+.Ft void
+.Fn srand48_deterministic "long seed"
 .Ft "unsigned short *"
 .Fn seed48 "unsigned short xseed[3]"
+.Ft "unsigned short *"
+.Fn seed48_deterministic "unsigned short xseed[3]"
 .Ft void
 .Fn lcong48 "unsigned short p[7]"
+.Ft void
+.Fn lcong48_deterministic "unsigned short p[7]"
 .Sh DESCRIPTION
 .Bf -symbolic
-This interface is not cryptographically secure, so consider using
-.Xr arc4random 3
-instead.
+Standards insist that this interface return deterministic results.
+Unsafe usage is very common, so
+.Ox
+changed the subsystem to return non-deterministic results by default.
 .Ef
 .Pp
-The
-.Fn rand48
-family of functions generates pseudo-random numbers using a linear
-congruential algorithm working on integers 48 bits in size.
-The particular formula employed is
-r(n+1) = (a * r(n) + c) mod m
-where the default values are
-for the multiplicand a = 0xfdeece66d = 25214903917 and
-the addend c = 0xb = 11.
-The modulus is always fixed at m = 2 ** 48.
-r(n) is called the seed of the random number generator.
+To satisfy portable code,
+.Fn srand48 ,
+.Fn seed48 ,
+or
+.Fn lcong48
+should be called to initialize the subsystem.
+In
+.Ox
+the
+seeding parameters are ignored, and strong random number results will be
+provided from
+.Xr arc4random 3.
+In other systems, the
+parameters prime a simplistic deterministic algorithm.
 .Pp
-For all the six generator routines described next, the first
-computational step is to perform a single iteration of the algorithm.
+If the standardized behavior is required then
+.Fn srand48_deterministic ,
+.Fn seed48_deterministic ,
+and
+.Fn lcong48_deterministic
+can be substituted for
+.Fn srand48 ,
+.Fn seed48 ,
+and
+.Fn lcong48 .
+That will cause subsequent
+calls to
+.Fn drand48 ,
+.Fn lrand48 ,
+and
+.Fn jrand48
+to return results using the deterministic algorithm.
 .Pp
 .Fn drand48
 and
@@ -91,6 +119,21 @@ return values of type long in the range
 [-2**31, 2**31-1].
 The high-order (32) bits of r(n+1) are loaded into the returned value.
 .Pp
+In the deterministic mode, the
+.Fn rand48
+family of functions generates numbers using a linear congruential
+algorithm working on integers 48 bits in size.
+The particular formula employed is
+r(n+1) = (a * r(n) + c) mod m
+where the default values are
+for the multiplicand a = 0xfdeece66d = 25214903917 and
+the addend c = 0xb = 11.
+The modulus is always fixed at m = 2 ** 48.
+r(n) is called the seed of the random number generator.
+.Pp
+For all the six generator routines described next, the first
+computational step is to perform a single iteration of the algorithm.
+.Pp
 .Fn drand48 ,
 .Fn lrand48 ,
 and
@@ -110,7 +153,7 @@ holds the least significant bits.
 .Pp
 All functions share the same multiplicand and addend.
 .Pp
-.Fn srand48
+.Fn srand48_deterministic
 is used to initialize the internal buffer r(n) of
 .Fn drand48 ,
 .Fn lrand48 ,
@@ -121,7 +164,7 @@ of r(n), with the lower 16 bits of r(n) arbitrarily being set to 0x330e.
 Additionally, the constant multiplicand and addend of the algorithm are
 reset to the default values given above.
 .Pp
-.Fn seed48
+.Fn seed48_deterministic
 also initializes the internal buffer r(n) of
 .Fn drand48 ,
 .Fn lrand48 ,
@@ -131,14 +174,14 @@ but here all 48 bits of the seed can be specified in an array of 3 shorts,
 where the zeroth member specifies the lowest bits.
 Again, the constant multiplicand and addend of the algorithm are
 reset to the default values given above.
-.Fn seed48
+.Fn seed48_deterministic
 returns a pointer to an array of 3 shorts which contains the old seed.
 This array is statically allocated, so its contents are lost after
 each new call to
-.Fn seed48 .
+.Fn seed48_deterministic .
 .Pp
 Finally,
-.Fn lcong48
+.Fn lcong48_deterministic
 allows full control over the multiplicand and addend used in
 .Fn drand48 ,
 .Fn erand48 ,
@@ -169,14 +212,27 @@ The
 .Fn drand48 ,
 .Fn erand48 ,
 .Fn jrand48 ,
-.Fn lcong48 ,
 .Fn lrand48 ,
 .Fn mrand48 ,
-.Fn nrand48 ,
-.Fn seed48 ,
 and
-.Fn srand48
+.Fn nrand48 ,
 functions conform to
 .St -p1003.1-2008 .
+.Pp
+The
+.Fn seed48 ,
+.Fn srand48 ,
+and
+.Fn lcong48
+function do not conform to
+.St -ansiC ,
+intentionally.
+.Pp
+The
+.Fn seed48_deterministic ,
+.Fn srand48_deterministic ,
+and
+.Fn lcong48_deterministic
+functions are OpenBSD extensions.
 .Sh AUTHORS
 .An Martin Birgmeier
diff --git a/src/lib/libc/stdlib/rand48.h b/src/lib/libc/stdlib/rand48.h
index afa49f65..ee701747 100644
--- a/src/lib/libc/stdlib/rand48.h
+++ b/src/lib/libc/stdlib/rand48.h
@@ -10,7 +10,7 @@
  * of any kind. I shall in no event be liable for anything that happens
  * to anyone/anything when using this software.
  *
- *	$OpenBSD: rand48.h,v 1.3 2002/02/16 21:27:24 millert Exp $
+ *	$OpenBSD: rand48.h,v 1.4 2014/12/08 21:45:20 deraadt Exp $
  */
 
 #ifndef _RAND48_H_
@@ -20,6 +20,7 @@
 #include <stdlib.h>
 
 void		__dorand48(unsigned short[3]);
+extern int	__rand48_deterministic;
 
 #define	RAND48_SEED_0	(0x330e)
 #define	RAND48_SEED_1	(0xabcd)
diff --git a/src/lib/libc/stdlib/random.3 b/src/lib/libc/stdlib/random.3
index b3bc560a..ad92b603 100644
--- a/src/lib/libc/stdlib/random.3
+++ b/src/lib/libc/stdlib/random.3
@@ -25,14 +25,15 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: random.3,v 1.26 2014/11/25 17:40:38 millert Exp $
+.\"	$OpenBSD: random.3,v 1.27 2014/12/08 21:45:20 deraadt Exp $
 .\"
-.Dd $Mdocdate: November 25 2014 $
+.Dd $Mdocdate: December 8 2014 $
 .Dt RANDOM 3
 .Os
 .Sh NAME
 .Nm random ,
 .Nm srandom ,
+.Nm srandom_deterministic ,
 .Nm srandomdev ,
 .Nm initstate ,
 .Nm setstate
@@ -44,6 +45,8 @@
 .Ft void
 .Fn srandom "unsigned int seed"
 .Ft void
+.Fn srandom_deterministic "unsigned int seed"
+.Ft void
 .Fn srandomdev void
 .Ft char *
 .Fn initstate "unsigned int seed" "char *state" "size_t n"
@@ -51,58 +54,48 @@
 .Fn setstate "char *state"
 .Sh DESCRIPTION
 .Bf -symbolic
-This interface is not cryptographically secure, so consider using
-.Xr arc4random 3
-instead.
+Standards insist that this interface return deterministic results.
+Unsafe usage is very common, so
+.Ox
+changed the subsystem to return non-deterministic results by default.
 .Ef
 .Pp
-The
-.Fn random
-function uses a non-linear additive feedback random number generator employing
-a default table of size 31 long integers to return successive pseudo-random
-numbers in the range from 0 to (2**31)\-1.
-The period of this random number generator is very large, approximately
-16*((2**31)\-1).
-.Pp
-The
-.Fn random
-and
+To satisfy portable code,
 .Fn srandom
-functions have (almost) the same calling sequence and initialization
-properties as
-.Xr rand 3 Ns / Ns Xr srand 3 .
-The difference is that
-.Xr rand
-produces a much less random sequence \(em in fact, the low dozen bits
-generated by rand go through a cyclic pattern.
-All the bits generated by
+or
+.Fn srandomdev
+may be called to initialize the subsystem.
+In
+.Ox
+the
+.Ar seed
+variable is ignored, and strong random number results will be provided from
+.Xr arc4random 3.
+In other systems, the
+.Ar seed
+variable primes a simplistic deterministic algorithm.
+.Pp
+If the standardized behavior is required
+.Fn srandom_deterministic
+can be substituted for
+.Fn srandom ,
+then subsequent
 .Fn random
-are usable.
-For example,
-.Sq Li random()&01
-will produce a random binary
-value.
+calls will return results using the deterministic algorithm.
 .Pp
-Like
-.Xr rand 3 ,
+In non-deterministic (default) mode, the
 .Fn random
-will by default produce a sequence of numbers that can be duplicated
-by calling
-.Fn srandom
-with
-.Ql 1
-as the seed.
+function returns results from
+.Xr arc4random 3
+in the range from 0 to (2**31)\-1.
 .Pp
-The
-.Fn srandomdev
-routine switches to an algorithm using state derived from
-random numbers obtained from the kernel.
-Note that this particular seeding procedure can generate
-states which are impossible to reproduce by calling
-.Fn srandom
-with any value, since the succeeding terms in the
-state buffer are no longer derived from the LC algorithm applied to
-a fixed seed.
+In deterministic mode, the
+.Fn random
+function uses a non-linear additive feedback random number generator employing
+a default table of size 31 long integers to return successive pseudo-random
+numbers in the range from 0 to (2**31)\-1.
+The period of this random number generator is very large, approximately
+16*((2**31)\-1), but the results are a deterministic sequence from the seed.
 .Pp
 The
 .Fn initstate
@@ -151,9 +144,12 @@ and
 is that the size of the state array does not have to be remembered after
 it is initialized.
 .Pp
-With 256 bytes of state information, the period of the random number
-generator is greater than 2**69
-which should be sufficient for most purposes.
+Use of
+.Fn srandom_deterministic ,
+.Fn initstate ,
+or
+.Fn setstate
+forces the subsystem into deterministic mode.
 .Sh DIAGNOSTICS
 If
 .Fn initstate
@@ -169,7 +165,6 @@ messages are printed on the standard error output.
 .Sh STANDARDS
 The
 .Fn random ,
-.Fn srandom ,
 .Fn initstate ,
 and
 .Fn setstate
@@ -177,14 +172,21 @@ functions conform to
 .St -xpg4.2 .
 .Pp
 The
+.Fn srandom
+function does not conform to
+.St -xpg4.2 ,
+intentionally.
+.Pp
+The
 .Fn srandomdev
 function is an extension.
+.Pp
+The
+.Fn srandom_deterministic
+function is an OpenBSD extension.
 .Sh HISTORY
 These
 functions appeared in
 .Bx 4.2 .
 .Sh AUTHORS
 .An Earl T. Cohen
-.Sh BUGS
-The historical implementation used to have very weak seeding.
-As a result, the random sequence did not vary much with the seed.
diff --git a/src/lib/libc/stdlib/random.c b/src/lib/libc/stdlib/random.c
index e4ff07ea..cba088c7 100644
--- a/src/lib/libc/stdlib/random.c
+++ b/src/lib/libc/stdlib/random.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: random.c,v 1.24 2014/10/13 20:54:13 chl Exp $ */
+/*	$OpenBSD: random.c,v 1.25 2014/12/08 21:45:20 deraadt Exp $ */
 /*
  * Copyright (c) 1983 Regents of the University of California.
  * All rights reserved.
@@ -176,7 +176,7 @@ static int rand_type = TYPE_3;
 static int rand_deg = DEG_3;
 static int rand_sep = SEP_3;
 
-static int use_arc4random;
+static int random_deterministic;
 
 _THREAD_PRIVATE_MUTEX(random);
 static long random_l(void);
@@ -203,7 +203,7 @@ srandom_l(unsigned int x)
 	int32_t test;
 	div_t val;
 
-	use_arc4random = 0;
+	random_deterministic = 1;
 	if (rand_type == TYPE_0)
 		state[0] = x;
 	else {
@@ -231,39 +231,23 @@ srandom_l(unsigned int x)
 void
 srandom(unsigned int x)
 {
-	LOCK();
-	srandom_l(x);
-	UNLOCK();
+	random_deterministic = 0;
 }
 
-#if defined(APIWARN)
-__warn_references(srandom,
-    "warning: srandom() seed choices are invariably poor");
-#endif
-
-/*
- * srandomdev:
- *
- * Many programs choose the seed value in a totally predictable manner.
- * This often causes problems.  We seed the generator using random data.
- * Note that this particular seeding procedure can generate states
- * which are impossible to reproduce by calling srandom() with any
- * value, since the succeeding terms in the state buffer are no longer
- * derived from the LC algorithm applied to a fixed seed.
- */
 void
 srandomdev(void)
+{
+	random_deterministic = 0;	/* back to the default */
+}
+
+void
+srandom_deterministic(unsigned int x)
 {
 	LOCK();
-	use_arc4random = 1;
+	srandom_l(x);
 	UNLOCK();
 }
 
-#if defined(APIWARN)
-__warn_references(srandomdev,
-    "warning: srandomdev() usage; consider switching to arc4random()");
-#endif
-
 /*
  * initstate:
  *
@@ -289,7 +273,7 @@ initstate(u_int seed, char *arg_state, size_t n)
 	char *ostate = (char *)(&state[-1]);
 
 	LOCK();
-	use_arc4random = 0;
+	random_deterministic = 1;
 	if (rand_type == TYPE_0)
 		state[-1] = rand_type;
 	else
@@ -354,7 +338,7 @@ setstate(char *arg_state)
 	char *ostate = (char *)(&state[-1]);
 
 	LOCK();
-	use_arc4random = 0;
+	random_deterministic = 1;
 	if (rand_type == TYPE_0)
 		state[-1] = rand_type;
 	else
@@ -405,7 +389,7 @@ random_l(void)
 {
 	int32_t i;
 
-	if (use_arc4random)
+	if (random_deterministic == 0)
 		return arc4random() & 0x7fffffff;
 
 	if (rand_type == TYPE_0)
@@ -431,8 +415,3 @@ random(void)
 	UNLOCK();
 	return r;
 }
-
-#if defined(APIWARN)
-__warn_references(random,
-    "warning: random() isn't random; consider using arc4random()");
-#endif
diff --git a/src/lib/libc/stdlib/seed48.c b/src/lib/libc/stdlib/seed48.c
index 583262f2..7acb4e6d 100644
--- a/src/lib/libc/stdlib/seed48.c
+++ b/src/lib/libc/stdlib/seed48.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: seed48.c,v 1.3 2005/08/08 08:05:37 espie Exp $ */
+/*	$OpenBSD: seed48.c,v 1.4 2014/12/08 21:45:20 deraadt Exp $ */
 /*
  * Copyright (c) 1993 Martin Birgmeier
  * All rights reserved.
@@ -20,9 +20,20 @@ extern unsigned short __rand48_add;
 
 unsigned short *
 seed48(unsigned short xseed[3])
+{
+	unsigned short *res;
+
+	res = seed48_deterministic(xseed);
+	__rand48_deterministic = 0;
+	return res;
+}
+
+unsigned short *
+seed48_deterministic(unsigned short xseed[3])
 {
 	static unsigned short sseed[3];
 
+	__rand48_deterministic = 1;
 	sseed[0] = __rand48_seed[0];
 	sseed[1] = __rand48_seed[1];
 	sseed[2] = __rand48_seed[2];
diff --git a/src/lib/libc/stdlib/srand48.c b/src/lib/libc/stdlib/srand48.c
index f76b6cca..115b9e82 100644
--- a/src/lib/libc/stdlib/srand48.c
+++ b/src/lib/libc/stdlib/srand48.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: srand48.c,v 1.3 2005/08/08 08:05:37 espie Exp $ */
+/*	$OpenBSD: srand48.c,v 1.4 2014/12/08 21:45:20 deraadt Exp $ */
 /*
  * Copyright (c) 1993 Martin Birgmeier
  * All rights reserved.
@@ -18,9 +18,19 @@ extern unsigned short __rand48_seed[3];
 extern unsigned short __rand48_mult[3];
 extern unsigned short __rand48_add;
 
+int     __rand48_deterministic;
+
 void
 srand48(long seed)
 {
+	srand48_deterministic(seed);
+	__rand48_deterministic = 0;
+}
+
+void
+srand48_deterministic(long seed)
+{
+	__rand48_deterministic = 1;
 	__rand48_seed[0] = RAND48_SEED_0;
 	__rand48_seed[1] = (unsigned short) seed;
 	__rand48_seed[2] = (unsigned short) (seed >> 16);