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Dependencies:   mbed

NetServices/lwip/netif/ppp/randm.c@1:f5ac63519541, 2014-03-05 (annotated)

Committer:
Michael J. Spencer
Date:
Wed Mar 05 06:14:02 2014 -0800
Revision:
1:f5ac63519541
Initial commit.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Michael J. Spencer 1:f5ac63519541 1 /*****************************************************************************
Michael J. Spencer 1:f5ac63519541 2 * randm.c - Random number generator program file.
Michael J. Spencer 1:f5ac63519541 3 *
Michael J. Spencer 1:f5ac63519541 4 * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
Michael J. Spencer 1:f5ac63519541 5 * Copyright (c) 1998 by Global Election Systems Inc.
Michael J. Spencer 1:f5ac63519541 6 *
Michael J. Spencer 1:f5ac63519541 7 * The authors hereby grant permission to use, copy, modify, distribute,
Michael J. Spencer 1:f5ac63519541 8 * and license this software and its documentation for any purpose, provided
Michael J. Spencer 1:f5ac63519541 9 * that existing copyright notices are retained in all copies and that this
Michael J. Spencer 1:f5ac63519541 10 * notice and the following disclaimer are included verbatim in any
Michael J. Spencer 1:f5ac63519541 11 * distributions. No written agreement, license, or royalty fee is required
Michael J. Spencer 1:f5ac63519541 12 * for any of the authorized uses.
Michael J. Spencer 1:f5ac63519541 13 *
Michael J. Spencer 1:f5ac63519541 14 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
Michael J. Spencer 1:f5ac63519541 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
Michael J. Spencer 1:f5ac63519541 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
Michael J. Spencer 1:f5ac63519541 17 * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
Michael J. Spencer 1:f5ac63519541 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
Michael J. Spencer 1:f5ac63519541 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
Michael J. Spencer 1:f5ac63519541 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
Michael J. Spencer 1:f5ac63519541 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
Michael J. Spencer 1:f5ac63519541 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
Michael J. Spencer 1:f5ac63519541 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Michael J. Spencer 1:f5ac63519541 24 *
Michael J. Spencer 1:f5ac63519541 25 ******************************************************************************
Michael J. Spencer 1:f5ac63519541 26 * REVISION HISTORY
Michael J. Spencer 1:f5ac63519541 27 *
Michael J. Spencer 1:f5ac63519541 28 * 03-01-01 Marc Boucher <marc@mbsi.ca>
Michael J. Spencer 1:f5ac63519541 29 * Ported to lwIP.
Michael J. Spencer 1:f5ac63519541 30 * 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
Michael J. Spencer 1:f5ac63519541 31 * Extracted from avos.
Michael J. Spencer 1:f5ac63519541 32 *****************************************************************************/
Michael J. Spencer 1:f5ac63519541 33
Michael J. Spencer 1:f5ac63519541 34 #include "lwip/opt.h"
Michael J. Spencer 1:f5ac63519541 35
Michael J. Spencer 1:f5ac63519541 36 #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
Michael J. Spencer 1:f5ac63519541 37
Michael J. Spencer 1:f5ac63519541 38 #include "md5.h"
Michael J. Spencer 1:f5ac63519541 39 #include "randm.h"
Michael J. Spencer 1:f5ac63519541 40
Michael J. Spencer 1:f5ac63519541 41 #include "ppp.h"
Michael J. Spencer 1:f5ac63519541 42 #include "pppdebug.h"
Michael J. Spencer 1:f5ac63519541 43
Michael J. Spencer 1:f5ac63519541 44 #include <string.h>
Michael J. Spencer 1:f5ac63519541 45
Michael J. Spencer 1:f5ac63519541 46 #if MD5_SUPPORT /* this module depends on MD5 */
Michael J. Spencer 1:f5ac63519541 47 #define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
Michael J. Spencer 1:f5ac63519541 48
Michael J. Spencer 1:f5ac63519541 49 /*****************************/
Michael J. Spencer 1:f5ac63519541 50 /*** LOCAL DATA STRUCTURES ***/
Michael J. Spencer 1:f5ac63519541 51 /*****************************/
Michael J. Spencer 1:f5ac63519541 52 static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
Michael J. Spencer 1:f5ac63519541 53 static long randCount = 0; /* Pseudo-random incrementer */
Michael J. Spencer 1:f5ac63519541 54
Michael J. Spencer 1:f5ac63519541 55
Michael J. Spencer 1:f5ac63519541 56 /***********************************/
Michael J. Spencer 1:f5ac63519541 57 /*** PUBLIC FUNCTION DEFINITIONS ***/
Michael J. Spencer 1:f5ac63519541 58 /***********************************/
Michael J. Spencer 1:f5ac63519541 59 /*
Michael J. Spencer 1:f5ac63519541 60 * Initialize the random number generator.
Michael J. Spencer 1:f5ac63519541 61 *
Michael J. Spencer 1:f5ac63519541 62 * Since this is to be called on power up, we don't have much
Michael J. Spencer 1:f5ac63519541 63 * system randomess to work with. Here all we use is the
Michael J. Spencer 1:f5ac63519541 64 * real-time clock. We'll accumulate more randomness as soon
Michael J. Spencer 1:f5ac63519541 65 * as things start happening.
Michael J. Spencer 1:f5ac63519541 66 */
Michael J. Spencer 1:f5ac63519541 67 void
Michael J. Spencer 1:f5ac63519541 68 avRandomInit()
Michael J. Spencer 1:f5ac63519541 69 {
Michael J. Spencer 1:f5ac63519541 70 avChurnRand(NULL, 0);
Michael J. Spencer 1:f5ac63519541 71 }
Michael J. Spencer 1:f5ac63519541 72
Michael J. Spencer 1:f5ac63519541 73 /*
Michael J. Spencer 1:f5ac63519541 74 * Churn the randomness pool on a random event. Call this early and often
Michael J. Spencer 1:f5ac63519541 75 * on random and semi-random system events to build randomness in time for
Michael J. Spencer 1:f5ac63519541 76 * usage. For randomly timed events, pass a null pointer and a zero length
Michael J. Spencer 1:f5ac63519541 77 * and this will use the system timer and other sources to add randomness.
Michael J. Spencer 1:f5ac63519541 78 * If new random data is available, pass a pointer to that and it will be
Michael J. Spencer 1:f5ac63519541 79 * included.
Michael J. Spencer 1:f5ac63519541 80 *
Michael J. Spencer 1:f5ac63519541 81 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
Michael J. Spencer 1:f5ac63519541 82 */
Michael J. Spencer 1:f5ac63519541 83 void
Michael J. Spencer 1:f5ac63519541 84 avChurnRand(char *randData, u32_t randLen)
Michael J. Spencer 1:f5ac63519541 85 {
Michael J. Spencer 1:f5ac63519541 86 MD5_CTX md5;
Michael J. Spencer 1:f5ac63519541 87
Michael J. Spencer 1:f5ac63519541 88 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
Michael J. Spencer 1:f5ac63519541 89 MD5Init(&md5);
Michael J. Spencer 1:f5ac63519541 90 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
Michael J. Spencer 1:f5ac63519541 91 if (randData) {
Michael J. Spencer 1:f5ac63519541 92 MD5Update(&md5, (u_char *)randData, randLen);
Michael J. Spencer 1:f5ac63519541 93 } else {
Michael J. Spencer 1:f5ac63519541 94 struct {
Michael J. Spencer 1:f5ac63519541 95 /* INCLUDE fields for any system sources of randomness */
Michael J. Spencer 1:f5ac63519541 96 char foobar;
Michael J. Spencer 1:f5ac63519541 97 } sysData;
Michael J. Spencer 1:f5ac63519541 98
Michael J. Spencer 1:f5ac63519541 99 /* Load sysData fields here. */
Michael J. Spencer 1:f5ac63519541 100 MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
Michael J. Spencer 1:f5ac63519541 101 }
Michael J. Spencer 1:f5ac63519541 102 MD5Final((u_char *)randPool, &md5);
Michael J. Spencer 1:f5ac63519541 103 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
Michael J. Spencer 1:f5ac63519541 104 }
Michael J. Spencer 1:f5ac63519541 105
Michael J. Spencer 1:f5ac63519541 106 /*
Michael J. Spencer 1:f5ac63519541 107 * Use the random pool to generate random data. This degrades to pseudo
Michael J. Spencer 1:f5ac63519541 108 * random when used faster than randomness is supplied using churnRand().
Michael J. Spencer 1:f5ac63519541 109 * Note: It's important that there be sufficient randomness in randPool
Michael J. Spencer 1:f5ac63519541 110 * before this is called for otherwise the range of the result may be
Michael J. Spencer 1:f5ac63519541 111 * narrow enough to make a search feasible.
Michael J. Spencer 1:f5ac63519541 112 *
Michael J. Spencer 1:f5ac63519541 113 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
Michael J. Spencer 1:f5ac63519541 114 *
Michael J. Spencer 1:f5ac63519541 115 * XXX Why does he not just call churnRand() for each block? Probably
Michael J. Spencer 1:f5ac63519541 116 * so that you don't ever publish the seed which could possibly help
Michael J. Spencer 1:f5ac63519541 117 * predict future values.
Michael J. Spencer 1:f5ac63519541 118 * XXX Why don't we preserve md5 between blocks and just update it with
Michael J. Spencer 1:f5ac63519541 119 * randCount each time? Probably there is a weakness but I wish that
Michael J. Spencer 1:f5ac63519541 120 * it was documented.
Michael J. Spencer 1:f5ac63519541 121 */
Michael J. Spencer 1:f5ac63519541 122 void
Michael J. Spencer 1:f5ac63519541 123 avGenRand(char *buf, u32_t bufLen)
Michael J. Spencer 1:f5ac63519541 124 {
Michael J. Spencer 1:f5ac63519541 125 MD5_CTX md5;
Michael J. Spencer 1:f5ac63519541 126 u_char tmp[16];
Michael J. Spencer 1:f5ac63519541 127 u32_t n;
Michael J. Spencer 1:f5ac63519541 128
Michael J. Spencer 1:f5ac63519541 129 while (bufLen > 0) {
Michael J. Spencer 1:f5ac63519541 130 n = LWIP_MIN(bufLen, RANDPOOLSZ);
Michael J. Spencer 1:f5ac63519541 131 MD5Init(&md5);
Michael J. Spencer 1:f5ac63519541 132 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
Michael J. Spencer 1:f5ac63519541 133 MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
Michael J. Spencer 1:f5ac63519541 134 MD5Final(tmp, &md5);
Michael J. Spencer 1:f5ac63519541 135 randCount++;
Michael J. Spencer 1:f5ac63519541 136 MEMCPY(buf, tmp, n);
Michael J. Spencer 1:f5ac63519541 137 buf += n;
Michael J. Spencer 1:f5ac63519541 138 bufLen -= n;
Michael J. Spencer 1:f5ac63519541 139 }
Michael J. Spencer 1:f5ac63519541 140 }
Michael J. Spencer 1:f5ac63519541 141
Michael J. Spencer 1:f5ac63519541 142 /*
Michael J. Spencer 1:f5ac63519541 143 * Return a new random number.
Michael J. Spencer 1:f5ac63519541 144 */
Michael J. Spencer 1:f5ac63519541 145 u32_t
Michael J. Spencer 1:f5ac63519541 146 avRandom()
Michael J. Spencer 1:f5ac63519541 147 {
Michael J. Spencer 1:f5ac63519541 148 u32_t newRand;
Michael J. Spencer 1:f5ac63519541 149
Michael J. Spencer 1:f5ac63519541 150 avGenRand((char *)&newRand, sizeof(newRand));
Michael J. Spencer 1:f5ac63519541 151
Michael J. Spencer 1:f5ac63519541 152 return newRand;
Michael J. Spencer 1:f5ac63519541 153 }
Michael J. Spencer 1:f5ac63519541 154
Michael J. Spencer 1:f5ac63519541 155 #else /* MD5_SUPPORT */
Michael J. Spencer 1:f5ac63519541 156
Michael J. Spencer 1:f5ac63519541 157 /*****************************/
Michael J. Spencer 1:f5ac63519541 158 /*** LOCAL DATA STRUCTURES ***/
Michael J. Spencer 1:f5ac63519541 159 /*****************************/
Michael J. Spencer 1:f5ac63519541 160 static int avRandomized = 0; /* Set when truely randomized. */
Michael J. Spencer 1:f5ac63519541 161 static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
Michael J. Spencer 1:f5ac63519541 162
Michael J. Spencer 1:f5ac63519541 163
Michael J. Spencer 1:f5ac63519541 164 /***********************************/
Michael J. Spencer 1:f5ac63519541 165 /*** PUBLIC FUNCTION DEFINITIONS ***/
Michael J. Spencer 1:f5ac63519541 166 /***********************************/
Michael J. Spencer 1:f5ac63519541 167 /*
Michael J. Spencer 1:f5ac63519541 168 * Initialize the random number generator.
Michael J. Spencer 1:f5ac63519541 169 *
Michael J. Spencer 1:f5ac63519541 170 * Here we attempt to compute a random number seed but even if
Michael J. Spencer 1:f5ac63519541 171 * it isn't random, we'll randomize it later.
Michael J. Spencer 1:f5ac63519541 172 *
Michael J. Spencer 1:f5ac63519541 173 * The current method uses the fields from the real time clock,
Michael J. Spencer 1:f5ac63519541 174 * the idle process counter, the millisecond counter, and the
Michael J. Spencer 1:f5ac63519541 175 * hardware timer tick counter. When this is invoked
Michael J. Spencer 1:f5ac63519541 176 * in startup(), then the idle counter and timer values may
Michael J. Spencer 1:f5ac63519541 177 * repeat after each boot and the real time clock may not be
Michael J. Spencer 1:f5ac63519541 178 * operational. Thus we call it again on the first random
Michael J. Spencer 1:f5ac63519541 179 * event.
Michael J. Spencer 1:f5ac63519541 180 */
Michael J. Spencer 1:f5ac63519541 181 void
Michael J. Spencer 1:f5ac63519541 182 avRandomInit()
Michael J. Spencer 1:f5ac63519541 183 {
Michael J. Spencer 1:f5ac63519541 184 #if 0
Michael J. Spencer 1:f5ac63519541 185 /* Get a pointer into the last 4 bytes of clockBuf. */
Michael J. Spencer 1:f5ac63519541 186 u32_t *lptr1 = (u32_t *)((char *)&clockBuf[3]);
Michael J. Spencer 1:f5ac63519541 187
Michael J. Spencer 1:f5ac63519541 188 /*
Michael J. Spencer 1:f5ac63519541 189 * Initialize our seed using the real-time clock, the idle
Michael J. Spencer 1:f5ac63519541 190 * counter, the millisecond timer, and the hardware timer
Michael J. Spencer 1:f5ac63519541 191 * tick counter. The real-time clock and the hardware
Michael J. Spencer 1:f5ac63519541 192 * tick counter are the best sources of randomness but
Michael J. Spencer 1:f5ac63519541 193 * since the tick counter is only 16 bit (and truncated
Michael J. Spencer 1:f5ac63519541 194 * at that), the idle counter and millisecond timer
Michael J. Spencer 1:f5ac63519541 195 * (which may be small values) are added to help
Michael J. Spencer 1:f5ac63519541 196 * randomize the lower 16 bits of the seed.
Michael J. Spencer 1:f5ac63519541 197 */
Michael J. Spencer 1:f5ac63519541 198 readClk();
Michael J. Spencer 1:f5ac63519541 199 avRandomSeed += *(u32_t *)clockBuf + *lptr1 + OSIdleCtr
Michael J. Spencer 1:f5ac63519541 200 + ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
Michael J. Spencer 1:f5ac63519541 201 #else
Michael J. Spencer 1:f5ac63519541 202 avRandomSeed += sys_jiffies(); /* XXX */
Michael J. Spencer 1:f5ac63519541 203 #endif
Michael J. Spencer 1:f5ac63519541 204
Michael J. Spencer 1:f5ac63519541 205 /* Initialize the Borland random number generator. */
Michael J. Spencer 1:f5ac63519541 206 srand((unsigned)avRandomSeed);
Michael J. Spencer 1:f5ac63519541 207 }
Michael J. Spencer 1:f5ac63519541 208
Michael J. Spencer 1:f5ac63519541 209 /*
Michael J. Spencer 1:f5ac63519541 210 * Randomize our random seed value. Here we use the fact that
Michael J. Spencer 1:f5ac63519541 211 * this function is called at *truely random* times by the polling
Michael J. Spencer 1:f5ac63519541 212 * and network functions. Here we only get 16 bits of new random
Michael J. Spencer 1:f5ac63519541 213 * value but we use the previous value to randomize the other 16
Michael J. Spencer 1:f5ac63519541 214 * bits.
Michael J. Spencer 1:f5ac63519541 215 */
Michael J. Spencer 1:f5ac63519541 216 void
Michael J. Spencer 1:f5ac63519541 217 avRandomize(void)
Michael J. Spencer 1:f5ac63519541 218 {
Michael J. Spencer 1:f5ac63519541 219 static u32_t last_jiffies;
Michael J. Spencer 1:f5ac63519541 220
Michael J. Spencer 1:f5ac63519541 221 if (!avRandomized) {
Michael J. Spencer 1:f5ac63519541 222 avRandomized = !0;
Michael J. Spencer 1:f5ac63519541 223 avRandomInit();
Michael J. Spencer 1:f5ac63519541 224 /* The initialization function also updates the seed. */
Michael J. Spencer 1:f5ac63519541 225 } else {
Michael J. Spencer 1:f5ac63519541 226 /* avRandomSeed += (avRandomSeed << 16) + TM1; */
Michael J. Spencer 1:f5ac63519541 227 avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
Michael J. Spencer 1:f5ac63519541 228 }
Michael J. Spencer 1:f5ac63519541 229 last_jiffies = sys_jiffies();
Michael J. Spencer 1:f5ac63519541 230 }
Michael J. Spencer 1:f5ac63519541 231
Michael J. Spencer 1:f5ac63519541 232 /*
Michael J. Spencer 1:f5ac63519541 233 * Return a new random number.
Michael J. Spencer 1:f5ac63519541 234 * Here we use the Borland rand() function to supply a pseudo random
Michael J. Spencer 1:f5ac63519541 235 * number which we make truely random by combining it with our own
Michael J. Spencer 1:f5ac63519541 236 * seed which is randomized by truely random events.
Michael J. Spencer 1:f5ac63519541 237 * Thus the numbers will be truely random unless there have been no
Michael J. Spencer 1:f5ac63519541 238 * operator or network events in which case it will be pseudo random
Michael J. Spencer 1:f5ac63519541 239 * seeded by the real time clock.
Michael J. Spencer 1:f5ac63519541 240 */
Michael J. Spencer 1:f5ac63519541 241 u32_t
Michael J. Spencer 1:f5ac63519541 242 avRandom()
Michael J. Spencer 1:f5ac63519541 243 {
Michael J. Spencer 1:f5ac63519541 244 return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
Michael J. Spencer 1:f5ac63519541 245 }
Michael J. Spencer 1:f5ac63519541 246
Michael J. Spencer 1:f5ac63519541 247 #endif /* MD5_SUPPORT */
Michael J. Spencer 1:f5ac63519541 248
Michael J. Spencer 1:f5ac63519541 249 #endif /* PPP_SUPPORT */