Diff: lwip/netif/ppp/randm.c

Revision:

12:8dc6b255af6c

Parent:

11:da4498f591ee

--- a/lwip/netif/ppp/randm.c	Thu Aug 05 15:01:33 2010 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,249 +0,0 @@
-/*****************************************************************************
-* randm.c - Random number generator program file.
-*
-* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
-* Copyright (c) 1998 by Global Election Systems Inc.
-*
-* The authors hereby grant permission to use, copy, modify, distribute,
-* and license this software and its documentation for any purpose, provided
-* that existing copyright notices are retained in all copies and that this
-* notice and the following disclaimer are included verbatim in any 
-* distributions. No written agreement, license, or royalty fee is required
-* for any of the authorized uses.
-*
-* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
-* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
-* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
-* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
-* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
-* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
-* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*
-******************************************************************************
-* REVISION HISTORY
-*
-* 03-01-01 Marc Boucher <marc@mbsi.ca>
-*   Ported to lwIP.
-* 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
-*   Extracted from avos.
-*****************************************************************************/
-
-#include "lwip/opt.h"
-
-#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
-
-#include "md5.h"
-#include "randm.h"
-
-#include "ppp.h"
-#include "pppdebug.h"
-
-#include <string.h>
-
-#if MD5_SUPPORT /* this module depends on MD5 */
-#define RANDPOOLSZ 16   /* Bytes stored in the pool of randomness. */
-
-/*****************************/
-/*** LOCAL DATA STRUCTURES ***/
-/*****************************/
-static char randPool[RANDPOOLSZ];   /* Pool of randomness. */
-static long randCount = 0;      /* Pseudo-random incrementer */
-
-
-/***********************************/
-/*** PUBLIC FUNCTION DEFINITIONS ***/
-/***********************************/
-/*
- * Initialize the random number generator.
- *
- * Since this is to be called on power up, we don't have much
- *  system randomess to work with.  Here all we use is the
- *  real-time clock.  We'll accumulate more randomness as soon
- *  as things start happening.
- */
-void
-avRandomInit()
-{
-  avChurnRand(NULL, 0);
-}
-
-/*
- * Churn the randomness pool on a random event.  Call this early and often
- *  on random and semi-random system events to build randomness in time for
- *  usage.  For randomly timed events, pass a null pointer and a zero length
- *  and this will use the system timer and other sources to add randomness.
- *  If new random data is available, pass a pointer to that and it will be
- *  included.
- *
- * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
- */
-void
-avChurnRand(char *randData, u32_t randLen)
-{
-  MD5_CTX md5;
-
-  /* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
-  MD5Init(&md5);
-  MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
-  if (randData) {
-    MD5Update(&md5, (u_char *)randData, randLen);
-  } else {
-    struct {
-      /* INCLUDE fields for any system sources of randomness */
-      char foobar;
-    } sysData;
-
-    /* Load sysData fields here. */
-    MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
-  }
-  MD5Final((u_char *)randPool, &md5);
-/*  LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
-}
-
-/*
- * Use the random pool to generate random data.  This degrades to pseudo
- *  random when used faster than randomness is supplied using churnRand().
- * Note: It's important that there be sufficient randomness in randPool
- *  before this is called for otherwise the range of the result may be
- *  narrow enough to make a search feasible.
- *
- * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
- *
- * XXX Why does he not just call churnRand() for each block?  Probably
- *  so that you don't ever publish the seed which could possibly help
- *  predict future values.
- * XXX Why don't we preserve md5 between blocks and just update it with
- *  randCount each time?  Probably there is a weakness but I wish that
- *  it was documented.
- */
-void
-avGenRand(char *buf, u32_t bufLen)
-{
-  MD5_CTX md5;
-  u_char tmp[16];
-  u32_t n;
-
-  while (bufLen > 0) {
-    n = LWIP_MIN(bufLen, RANDPOOLSZ);
-    MD5Init(&md5);
-    MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
-    MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
-    MD5Final(tmp, &md5);
-    randCount++;
-    MEMCPY(buf, tmp, n);
-    buf += n;
-    bufLen -= n;
-  }
-}
-
-/*
- * Return a new random number.
- */
-u32_t
-avRandom()
-{
-  u32_t newRand;
-
-  avGenRand((char *)&newRand, sizeof(newRand));
-
-  return newRand;
-}
-
-#else /* MD5_SUPPORT */
-
-/*****************************/
-/*** LOCAL DATA STRUCTURES ***/
-/*****************************/
-static int  avRandomized = 0;       /* Set when truely randomized. */
-static u32_t avRandomSeed = 0;      /* Seed used for random number generation. */
-
-
-/***********************************/
-/*** PUBLIC FUNCTION DEFINITIONS ***/
-/***********************************/
-/*
- * Initialize the random number generator.
- *
- * Here we attempt to compute a random number seed but even if
- * it isn't random, we'll randomize it later.
- *
- * The current method uses the fields from the real time clock,
- * the idle process counter, the millisecond counter, and the
- * hardware timer tick counter.  When this is invoked
- * in startup(), then the idle counter and timer values may
- * repeat after each boot and the real time clock may not be
- * operational.  Thus we call it again on the first random
- * event.
- */
-void
-avRandomInit()
-{
-#if 0
-  /* Get a pointer into the last 4 bytes of clockBuf. */
-  u32_t *lptr1 = (u32_t *)((char *)&clockBuf[3]);
-
-  /*
-   * Initialize our seed using the real-time clock, the idle
-   * counter, the millisecond timer, and the hardware timer
-   * tick counter.  The real-time clock and the hardware
-   * tick counter are the best sources of randomness but
-   * since the tick counter is only 16 bit (and truncated
-   * at that), the idle counter and millisecond timer
-   * (which may be small values) are added to help
-   * randomize the lower 16 bits of the seed.
-   */
-  readClk();
-  avRandomSeed += *(u32_t *)clockBuf + *lptr1 + OSIdleCtr
-           + ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
-#else
-  avRandomSeed += sys_jiffies(); /* XXX */
-#endif
-
-  /* Initialize the Borland random number generator. */
-  srand((unsigned)avRandomSeed);
-}
-
-/*
- * Randomize our random seed value.  Here we use the fact that
- * this function is called at *truely random* times by the polling
- * and network functions.  Here we only get 16 bits of new random
- * value but we use the previous value to randomize the other 16
- * bits.
- */
-void
-avRandomize(void)
-{
-  static u32_t last_jiffies;
-
-  if (!avRandomized) {
-    avRandomized = !0;
-    avRandomInit();
-    /* The initialization function also updates the seed. */
-  } else {
-    /* avRandomSeed += (avRandomSeed << 16) + TM1; */
-    avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
-  }
-  last_jiffies = sys_jiffies();
-}
-
-/*
- * Return a new random number.
- * Here we use the Borland rand() function to supply a pseudo random
- * number which we make truely random by combining it with our own
- * seed which is randomized by truely random events. 
- * Thus the numbers will be truely random unless there have been no
- * operator or network events in which case it will be pseudo random
- * seeded by the real time clock.
- */
-u32_t
-avRandom()
-{
-  return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
-}
-
-#endif /* MD5_SUPPORT */
-
-#endif /* PPP_SUPPORT */