diff options
| author |   deraadt <deraadt@openbsd.org> | 2021-02-12 17:03:51 +0000 |
|---|---|---|
| committer | deraadt <deraadt@openbsd.org> | 2021-02-12 17:03:51 +0000 |
| commit | 70d9094f4044ec4d667009ef66d835cce8e9a22a (patch) | |
| tree | ff6efc4790783abc990ba4d1aaf2eae109ae76af | |
| parent | pf_remove_divert_state() is an entry point into pf, modifying the pf state (diff) | |
| download | wireguard-openbsd-70d9094f4044ec4d667009ef66d835cce8e9a22a.tar.xz wireguard-openbsd-70d9094f4044ec4d667009ef66d835cce8e9a22a.zip | |
Some people still argue that rand(3) and random(3) have suitable deterministic
use cases, so explain the situation a bit more. Since the 80's, I estimate
around 5 algorithm changes, so any chosen seed is unrepeatable UB.
+The deterministic sequence algorithm changed a number of times since
+original development, is underspecified, and should not be relied upon to
+remain consistent between platforms and over time.
ok jmc kettenis
| -rw-r--r-- | lib/libc/stdlib/rand.3 | 7 | ||||
| -rw-r--r-- | lib/libc/stdlib/random.3 | 7 |
2 files changed, 10 insertions, 4 deletions
diff --git a/lib/libc/stdlib/rand.3 b/lib/libc/stdlib/rand.3 index 2fd88ac8a4b..76278c871ab 100644 --- a/lib/libc/stdlib/rand.3 +++ b/lib/libc/stdlib/rand.3 @@ -29,9 +29,9 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.\" $OpenBSD: rand.3,v 1.19 2014/12/09 21:55:39 jmc Exp $ +.\" $OpenBSD: rand.3,v 1.20 2021/02/12 17:03:51 deraadt Exp $ .\" -.Dd $Mdocdate: December 9 2014 $ +.Dd $Mdocdate: February 12 2021 $ .Dt RAND 3 .Os .Sh NAME @@ -78,6 +78,9 @@ can be substituted for then subsequent .Fn rand calls will return results using the deterministic algorithm. +The deterministic sequence algorithm changed a number of times since +original development, is underspecified, and should not be relied upon to +remain consistent between platforms and over time. .Pp The .Fn rand diff --git a/lib/libc/stdlib/random.3 b/lib/libc/stdlib/random.3 index 020c72805f1..0770d20f09b 100644 --- a/lib/libc/stdlib/random.3 +++ b/lib/libc/stdlib/random.3 @@ -25,9 +25,9 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.\" $OpenBSD: random.3,v 1.28 2014/12/09 21:55:39 jmc Exp $ +.\" $OpenBSD: random.3,v 1.29 2021/02/12 17:03:51 deraadt Exp $ .\" -.Dd $Mdocdate: December 9 2014 $ +.Dd $Mdocdate: February 12 2021 $ .Dt RANDOM 3 .Os .Sh NAME @@ -96,6 +96,9 @@ 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. +The deterministic sequence algorithm changed a number of times since +original development, is underspecified, and should not be relied upon to +remain consistent between platforms and over time. .Pp The .Fn initstate |