diff options
author | nbd <nbd@3c298f89-4303-0410-b956-a3cf2f4a3e73> | 2012-10-10 12:32:29 +0000 |
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committer | nbd <nbd@3c298f89-4303-0410-b956-a3cf2f4a3e73> | 2012-10-10 12:32:29 +0000 |
commit | 9c8997d54dc9df184bfcedeabf0b3c85cf5e6753 (patch) | |
tree | 46b83031a0da1b4458317413c00d13c252c72afa /package/network/services/ead/src/tinysrp/t_truerand.c | |
parent | eecf5b17520f6b3b6ffb45ac7dca298d93b27501 (diff) |
packages: sort network related packages into package/network/
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@33688 3c298f89-4303-0410-b956-a3cf2f4a3e73
Diffstat (limited to 'package/network/services/ead/src/tinysrp/t_truerand.c')
-rw-r--r-- | package/network/services/ead/src/tinysrp/t_truerand.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/package/network/services/ead/src/tinysrp/t_truerand.c b/package/network/services/ead/src/tinysrp/t_truerand.c new file mode 100644 index 000000000..fa0d6ce60 --- /dev/null +++ b/package/network/services/ead/src/tinysrp/t_truerand.c @@ -0,0 +1,151 @@ +/* + * Physically random numbers (very nearly uniform) + * D. P. Mitchell + * Modified by Matt Blaze 7/95 + */ +/* + * The authors of this software are Don Mitchell and Matt Blaze. + * Copyright (c) 1995 by AT&T. + * Permission to use, copy, and modify this software without fee + * is hereby granted, provided that this entire notice is included in + * all copies of any software which is or includes a copy or + * modification of this software and in all copies of the supporting + * documentation for such software. + * + * This software may be subject to United States export controls. + * + * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED + * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR AT&T MAKE ANY + * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY + * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. + */ + +/* + * WARNING: depending on the particular platform, raw_truerand() + * output may be biased or correlated. In general, you can expect + * about 16 bits of "pseudo-entropy" out of each 32 bit word returned + * by truerand(), but it may not be uniformly diffused. You should + * raw_therefore run the output through some post-whitening function + * (like MD5 or DES or whatever) before using it to generate key + * material. (RSAREF's random package does this for you when you feed + * raw_truerand() bits to the seed input function.) + * + * The application interface, for 8, 16, and 32 bit properly "whitened" + * random numbers, can be found in trand8(), trand16(), and trand32(). + * Use those instead of calling raw_truerand() directly. + * + * The basic idea here is that between clock "skew" and various + * hard-to-predict OS event arrivals, counting a tight loop will yield + * a little (maybe a third of a bit or so) of "good" randomness per + * interval clock tick. This seems to work well even on unloaded + * machines. If there is a human operator at the machine, you should + * augment truerand with other measure, like keyboard event timing. + * On server machines (e.g., when you need to generate a + * Diffie-Hellman secret) truerand alone may be good enough. + * + * Test these assumptions on your own platform before fielding a + * system based on this software or these techniques. + * + * This software seems to work well (at 10 or so bits per + * raw_truerand() call) on a Sun Sparc-20 under SunOS 4.1.3 and on a + * P100 under BSDI 2.0. You're on your own elsewhere. + * + */ + +#include "t_defines.h" + +#include <signal.h> +#include <setjmp.h> +#include <sys/time.h> +#include <math.h> +#include <stdio.h> + +#ifdef OLD_TRUERAND +static jmp_buf env; +#endif +static unsigned volatile count +#ifndef OLD_TRUERAND + , done = 0 +#endif +; + +static unsigned ocount; +static unsigned buffer; + +static void +tick() +{ + struct itimerval it, oit; + + it.it_interval.tv_sec = 0; + it.it_interval.tv_usec = 0; + it.it_value.tv_sec = 0; + it.it_value.tv_usec = 16665; + if (setitimer(ITIMER_REAL, &it, &oit) < 0) + perror("tick"); +} + +static void +interrupt() +{ + if (count) { +#ifdef OLD_TRUERAND + longjmp(env, 1); +#else + ++done; + return; +#endif + } + + (void) signal(SIGALRM, interrupt); + tick(); +} + +static unsigned long +roulette() +{ +#ifdef OLD_TRUERAND + if (setjmp(env)) { + count ^= (count>>3) ^ (count>>6) ^ ocount; + count &= 0x7; + ocount=count; + buffer = (buffer<<3) ^ count; + return buffer; + } +#else + done = 0; +#endif + (void) signal(SIGALRM, interrupt); + count = 0; + tick(); +#ifdef OLD_TRUERAND + for (;;) +#else + while(done == 0) +#endif + count++; /* about 1 MHz on VAX 11/780 */ +#ifndef OLD_TRUERAND + count ^= (count>>3) ^ (count>>6) ^ ocount; + count &= 0x7; + ocount=count; + buffer = (buffer<<3) ^ count; + return buffer; +#endif +} + +unsigned long +raw_truerand() +{ + count=0; + (void) roulette(); + (void) roulette(); + (void) roulette(); + (void) roulette(); + (void) roulette(); + (void) roulette(); + (void) roulette(); + (void) roulette(); + (void) roulette(); + (void) roulette(); + return roulette(); +} |