projects / apple / libc.git / blame
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1 | .\" $OpenBSD: arc4random.3,v 1.2 1997/04/27 22:40:25 angelos Exp $ |
| 2 | .\" Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de> | |
| 3 | .\" All rights reserved. | |
| 4 | .\" | |
| 5 | .\" Redistribution and use in source and binary forms, with or without | |
| 6 | .\" modification, are permitted provided that the following conditions | |
| 7 | .\" are met: | |
| 8 | .\" 1. Redistributions of source code must retain the above copyright | |
| 9 | .\" notice, this list of conditions and the following disclaimer. | |
| 10 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
| 11 | .\" notice, this list of conditions and the following disclaimer in the | |
| 12 | .\" documentation and/or other materials provided with the distribution. | |
| 13 | .\" 3. All advertising materials mentioning features or use of this software | |
| 14 | .\" must display the following acknowledgement: | |
| 15 | .\" This product includes software developed by Niels Provos. | |
| 16 | .\" 4. The name of the author may not be used to endorse or promote products | |
| 17 | .\" derived from this software without specific prior written permission. | |
| 18 | .\" | |
| 19 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
| 20 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
| 21 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
| 22 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
| 23 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
| 24 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 25 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| 26 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 27 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
| 28 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 29 | .\" | |
| 30 | .\" Manual page, using -mandoc macros | |
| 31 | .\" $FreeBSD: src/lib/libc/gen/arc4random.3,v 1.12 2001/10/01 16:08:50 ru Exp $ | |
| 32 | .\" | |
| 33 | .Dd April 15, 1997 | |
| 34 | .Dt ARC4RANDOM 3 | |
| 35 | .Os | |
| 36 | .Sh NAME | |
| 37 | .Nm arc4random , | |
| 38 | .Nm arc4random_stir , | |
| 39 | .Nm arc4random_addrandom | |
| 40 | .Nd arc4 random number generator | |
| 41 | .Sh LIBRARY | |
| 42 | .Lb libc | |
| 43 | .Sh SYNOPSIS | |
| 44 | .In stdlib.h | |
| 45 | .Ft u_int32_t | |
| 46 | .Fn arc4random "void" | |
| 47 | .Ft void | |
| 48 | .Fn arc4random_stir "void" | |
| 49 | .Ft void | |
| 50 | .Fn arc4random_addrandom "unsigned char *dat" "int datlen" | |
| 51 | .Sh DESCRIPTION | |
| 52 | The | |
| 53 | .Fn arc4random | |
| 54 | function uses the key stream generator employed by the | |
| 55 | arc4 cipher, which uses 8*8 8 bit S-Boxes. | |
| 56 | The S-Boxes | |
| 57 | can be in about | |
| 58 | .if t 2\u\s71700\s10\d | |
| 59 | .if n (2**1700) | |
| 60 | states. | |
| 61 | .Pp | |
| 62 | The | |
| 63 | .Fn arc4random_stir | |
| 64 | function reads data from | |
| 65 | .Pa /dev/urandom | |
| 66 | and uses it to permute the S-Boxes via | |
| 67 | .Fn arc4random_addrandom . | |
| 68 | .Pp | |
| 69 | There is no need to call | |
| 70 | .Fn arc4random_stir | |
| 71 | before using | |
| 72 | .Fn arc4random , | |
| 73 | since | |
| 74 | .Fn arc4random | |
| 75 | automatically initializes itself. | |
| 76 | .Sh SEE ALSO | |
| 77 | .Xr rand 3 , | |
| 78 | .Xr random 3 , | |
| 79 | .Xr srandomdev 3 | |
| 80 | .Sh HISTORY | |
| 81 | .Pa RC4 | |
| 82 | has been designed by RSA Data Security, Inc. | |
| 83 | It was posted anonymously | |
| 84 | to the USENET and was confirmed to be equivalent by several sources who | |
| 85 | had access to the original cipher. | |
| 86 | Since | |
| 87 | .Pa RC4 | |
| 88 | used to be a trade secret, the cipher is now referred to as | |
| 89 | .Pa ARC4 . |