uint32_t
arc4random(
void
)
)
function provides a high quality 32-bit pseudo-random
number very quickly.
arc4random(
)
seeds itself on a regular basis from the kernel strong random number
subsystem described in
rnd(4).
On each call, an ARC4 generator is used to generate a new result.
The
arc4random(
)
function uses the ARC4 cipher key stream generator,
which uses 8*8 8 bit S-Boxes.
The S-Boxes can be in about (2**1700) states.
arc4random()
fits into a middle ground not covered by other subsystems such as
the strong, slow, and resource expensive random
devices described in
rnd(4)
versus the fast but poor quality interfaces such as
random(
).
RC4
was designed by RSA Data Security, Inc.
It was considered a trade secret, but not trademarked.
Because it was a trade secret, it obviously could not be patented.
A clone of this was posted anonymously to USENET and confirmed to
be equivalent by several sources who had access to the original cipher.
Because of the trade secret situation, RSA Data Security, Inc. can do
nothing about the release of the ARC4 algorithm.
Since
RC4
used to be a trade secret, the cipher is now referred to as
ARC4
.
These functions first appeared in OpenBSD2.1.