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arc4random, arc4random_stir, arc4random_addrandom - arc4 random number



      arc4random, arc4random_stir, arc4random_addrandom - arc4 random number


      Standard C Library (libc, -lc)


      #include <stdlib.h>
      arc4random_addrandom(unsigned char *dat, int datlen);


      The arc4random() function uses the key stream generator employed by the
      arc4 cipher, which uses 8*8 8 bit S-Boxes.  The S-Boxes can be in about
      (2**1700) states.  The arc4random() function returns pseudo-random num‐
      bers in the range of 0 to (2**32)−1, and therefore has twice the range of
      rand(3) and random(3).
      The arc4random_stir() function reads data from /dev/urandom and uses it
      to permute the S-Boxes via arc4random_addrandom().
      There is no need to call arc4random_stir() before using arc4random(),
      since arc4random() automatically initializes itself.


      The following produces a drop-in replacement for the traditional rand()
      and random() functions using arc4random():
            #define foo4random() (arc4random() % ((unsigned)RAND_MAX + 1))
      rand(3), random(3), srandomdev(3)


      RC4 has been designed by RSA Data Security, Inc.  It was posted anony‐
      mously to the USENET and was confirmed to be equivalent by several
      sources who had access to the original cipher.  Since RC4 used to be a
      trade secret, the cipher is now referred to as ARC4.


Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.