diff options
Diffstat (limited to 'src/arc4random.3')
| -rw-r--r-- | src/arc4random.3 | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/src/arc4random.3 b/src/arc4random.3 index 09c24c6..1043602 100644 --- a/src/arc4random.3 +++ b/src/arc4random.3 @@ -28,13 +28,15 @@ .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" Manual page, using -mandoc macros -.\" $FreeBSD: /repoman/r/ncvs/src/lib/libc/gen/arc4random.3,v 1.16 2003/07/31 06:18:24 das Exp $ +.\" $FreeBSD$ .\" .Dd April 15, 1997 .Dt ARC4RANDOM 3 .Os .Sh NAME .Nm arc4random , +.Nm arc4random_buf , +.Nm arc4random_uniform , .Nm arc4random_stir , .Nm arc4random_addrandom .Nd arc4 random number generator @@ -46,6 +48,10 @@ .Ft u_int32_t .Fn arc4random "void" .Ft void +.Fn arc4random_buf "void *buf" "size_t nbytes" +.Ft u_int32_t +.Fn arc4random_uniform "u_int32_t upper_bound" +.Ft void .Fn arc4random_stir "void" .Ft void .Fn arc4random_addrandom "unsigned char *dat" "int datlen" @@ -69,6 +75,21 @@ and therefore has twice the range of and .Xr random 3 . .Pp +.Fn arc4random_buf +function fills the region +.Fa buf +of length +.Fa nbytes +with ARC4-derived random data. +.Pp +.Fn arc4random_uniform +will return a uniformly distributed random number less than +.Fa upper_bound . +.Fn arc4random_uniform +is recommended over constructions like +.Dq Li arc4random() % upper_bound +as it avoids "modulo bias" when the upper bound is not a power of two. +.Pp The .Fn arc4random_stir function reads data from @@ -79,10 +100,9 @@ and uses it to permute the S-Boxes via There is no need to call .Fn arc4random_stir before using -.Fn arc4random , -since .Fn arc4random -automatically initializes itself. +functions family, since +they automatically initialize themselves. .Sh EXAMPLES The following produces a drop-in replacement for the traditional .Fn rand |