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ARC4RANDOM(3) FreeBSD Library Functions Manual ARC4RANDOM(3) NAME arc4random, arc4random_stir, arc4random_addrandom -- arc4 random number generator LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <stdlib.h> u_int32_t arc4random(void); void arc4random_stir(void); void arc4random_addrandom(unsigned char *dat, int datlen); DESCRIPTION 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. EXAMPLES The following produces a drop-in replacement for the traditional rand() and random() functions using arc4random(): #define foo4random() (arc4random() % ((unsigned)RAND_MAX + 1)) SEE ALSO rand(3), random(3), srandomdev(3) HISTORY 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. FreeBSD 11.1 April 15, 1997 FreeBSD 11.1
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | HISTORY
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