diff options
Diffstat (limited to 'src/lib/libc/crypt/arc4random.3')
| -rw-r--r-- | src/lib/libc/crypt/arc4random.3 | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/src/lib/libc/crypt/arc4random.3 b/src/lib/libc/crypt/arc4random.3 new file mode 100644 index 0000000000..d8e0f8cda6 --- /dev/null +++ b/src/lib/libc/crypt/arc4random.3 | |||
| @@ -0,0 +1,110 @@ | |||
| 1 | .\" $OpenBSD: arc4random.3,v 1.17 2000/12/21 14:07:41 aaron Exp $ | ||
| 2 | .\" | ||
| 3 | .\" Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de> | ||
| 4 | .\" All rights reserved. | ||
| 5 | .\" | ||
| 6 | .\" Redistribution and use in source and binary forms, with or without | ||
| 7 | .\" modification, are permitted provided that the following conditions | ||
| 8 | .\" are met: | ||
| 9 | .\" 1. Redistributions of source code must retain the above copyright | ||
| 10 | .\" notice, this list of conditions and the following disclaimer. | ||
| 11 | .\" 2. Redistributions in binary form must reproduce the above copyright | ||
| 12 | .\" notice, this list of conditions and the following disclaimer in the | ||
| 13 | .\" documentation and/or other materials provided with the distribution. | ||
| 14 | .\" 3. All advertising materials mentioning features or use of this software | ||
| 15 | .\" must display the following acknowledgement: | ||
| 16 | .\" This product includes software developed by Niels Provos. | ||
| 17 | .\" 4. The name of the author may not be used to endorse or promote products | ||
| 18 | .\" derived from this software without specific prior written permission. | ||
| 19 | .\" | ||
| 20 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | ||
| 21 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | ||
| 22 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | ||
| 23 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | ||
| 24 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | ||
| 25 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | ||
| 26 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | ||
| 27 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||
| 28 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | ||
| 29 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
| 30 | .\" | ||
| 31 | .\" Manual page, using -mandoc macros | ||
| 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 SYNOPSIS | ||
| 42 | .Fd #include <stdlib.h> | ||
| 43 | .Ft u_int32_t | ||
| 44 | .Fn arc4random "void" | ||
| 45 | .Ft void | ||
| 46 | .Fn arc4random_stir "void" | ||
| 47 | .Ft void | ||
| 48 | .Fn arc4random_addrandom "u_char *dat" "int datlen" | ||
| 49 | .Sh DESCRIPTION | ||
| 50 | The | ||
| 51 | .Fn arc4random | ||
| 52 | function provides a high quality 32-bit pseudo-random | ||
| 53 | number very quickly. | ||
| 54 | .Fn arc4random | ||
| 55 | seeds itself on a regular basis from the kernel strong random number | ||
| 56 | subsystem described in | ||
| 57 | .Xr random 4 . | ||
| 58 | On each call, an ARC4 generator is used to generate a new result. | ||
| 59 | The | ||
| 60 | .Fn arc4random | ||
| 61 | function uses the ARC4 cipher key stream generator, | ||
| 62 | which uses 8*8 8 bit S-Boxes. | ||
| 63 | The S-Boxes can be in about (2**1700) states. | ||
| 64 | .Pp | ||
| 65 | .Fn arc4random | ||
| 66 | fits into a middle ground not covered by other subsystems such as | ||
| 67 | the strong, slow, and resource expensive random | ||
| 68 | devices described in | ||
| 69 | .Xr random 4 | ||
| 70 | versus the fast but poor quality interfaces described in | ||
| 71 | .Xr rand 3 , | ||
| 72 | .Xr random 3 , | ||
| 73 | and | ||
| 74 | .Xr drand48 3 . | ||
| 75 | .Pp | ||
| 76 | The | ||
| 77 | .Fn arc4random_stir | ||
| 78 | function reads data from | ||
| 79 | .Pa /dev/arandom | ||
| 80 | and uses it to permute the S-Boxes via | ||
| 81 | .Fn arc4random_addrandom . | ||
| 82 | .Pp | ||
| 83 | There is no need to call | ||
| 84 | .Fn arc4random_stir | ||
| 85 | before using | ||
| 86 | .Fn arc4random , | ||
| 87 | since | ||
| 88 | .Fn arc4random | ||
| 89 | automatically initializes itself. | ||
| 90 | .Sh SEE ALSO | ||
| 91 | .Xr rand 3 , | ||
| 92 | .Xr rand48 3 , | ||
| 93 | .Xr random 3 | ||
| 94 | .Sh HISTORY | ||
| 95 | An algorithm called | ||
| 96 | .Pa RC4 | ||
| 97 | was designed by RSA Data Security, Inc. | ||
| 98 | It was considered a trade secret, but not trademarked. | ||
| 99 | Because it was a trade secret, it obviously could not be patented. | ||
| 100 | A clone of this was posted anonymously to USENET and confirmed to | ||
| 101 | be equivalent by several sources who had access to the original cipher. | ||
| 102 | Because of the trade secret situation, RSA Data Security, Inc. can do | ||
| 103 | nothing about the release of the ARC4 algorithm. | ||
| 104 | Since | ||
| 105 | .Pa RC4 | ||
| 106 | used to be a trade secret, the cipher is now referred to as | ||
| 107 | .Pa ARC4 . | ||
| 108 | .Pp | ||
| 109 | These functions first appeared in | ||
| 110 | .Ox 2.1 . | ||