packages: sort network related packages into package/network/

[openwrt/staging/jogo.git] / package / network / services / ead / src / tinysrp / t_truerand.c

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 (file)
index 0000000..fa0d6ce
--- /dev/null
+++ b/package/network/services/ead/src/tinysrp/t_truerand.c
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+/*
+ *      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();
+}