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netif/ppp/randm.c@30:cb9095482c25, 2015-04-07 (annotated)

Committer:
klauss
Date:
Tue Apr 07 14:27:01 2015 +0000
Revision:
30:cb9095482c25
Parent:
0:51ac1d130fd4 
wip

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 0:51ac1d130fd4 1 /*****************************************************************************
mbed_official 0:51ac1d130fd4 2 * randm.c - Random number generator program file.
mbed_official 0:51ac1d130fd4 3 *
mbed_official 0:51ac1d130fd4 4 * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
mbed_official 0:51ac1d130fd4 5 * Copyright (c) 1998 by Global Election Systems Inc.
mbed_official 0:51ac1d130fd4 6 *
mbed_official 0:51ac1d130fd4 7 * The authors hereby grant permission to use, copy, modify, distribute,
mbed_official 0:51ac1d130fd4 8 * and license this software and its documentation for any purpose, provided
mbed_official 0:51ac1d130fd4 9 * that existing copyright notices are retained in all copies and that this
mbed_official 0:51ac1d130fd4 10 * notice and the following disclaimer are included verbatim in any
mbed_official 0:51ac1d130fd4 11 * distributions. No written agreement, license, or royalty fee is required
mbed_official 0:51ac1d130fd4 12 * for any of the authorized uses.
mbed_official 0:51ac1d130fd4 13 *
mbed_official 0:51ac1d130fd4 14 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
mbed_official 0:51ac1d130fd4 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
mbed_official 0:51ac1d130fd4 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
mbed_official 0:51ac1d130fd4 17 * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
mbed_official 0:51ac1d130fd4 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
mbed_official 0:51ac1d130fd4 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
mbed_official 0:51ac1d130fd4 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
mbed_official 0:51ac1d130fd4 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
mbed_official 0:51ac1d130fd4 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
mbed_official 0:51ac1d130fd4 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
mbed_official 0:51ac1d130fd4 24 *
mbed_official 0:51ac1d130fd4 25 ******************************************************************************
mbed_official 0:51ac1d130fd4 26 * REVISION HISTORY
mbed_official 0:51ac1d130fd4 27 *
mbed_official 0:51ac1d130fd4 28 * 03-01-01 Marc Boucher <marc@mbsi.ca>
mbed_official 0:51ac1d130fd4 29 * Ported to lwIP.
mbed_official 0:51ac1d130fd4 30 * 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
mbed_official 0:51ac1d130fd4 31 * Extracted from avos.
mbed_official 0:51ac1d130fd4 32 *****************************************************************************/
mbed_official 0:51ac1d130fd4 33
mbed_official 0:51ac1d130fd4 34 #include "lwip/opt.h"
mbed_official 0:51ac1d130fd4 35
mbed_official 0:51ac1d130fd4 36 #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
mbed_official 0:51ac1d130fd4 37
mbed_official 0:51ac1d130fd4 38 #include "md5.h"
mbed_official 0:51ac1d130fd4 39 #include "randm.h"
mbed_official 0:51ac1d130fd4 40
mbed_official 0:51ac1d130fd4 41 #include "ppp.h"
mbed_official 0:51ac1d130fd4 42 #include "pppdebug.h"
mbed_official 0:51ac1d130fd4 43
mbed_official 0:51ac1d130fd4 44 #include <string.h>
mbed_official 0:51ac1d130fd4 45
mbed_official 0:51ac1d130fd4 46 #if MD5_SUPPORT /* this module depends on MD5 */
mbed_official 0:51ac1d130fd4 47 #define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
mbed_official 0:51ac1d130fd4 48
mbed_official 0:51ac1d130fd4 49 /*****************************/
mbed_official 0:51ac1d130fd4 50 /*** LOCAL DATA STRUCTURES ***/
mbed_official 0:51ac1d130fd4 51 /*****************************/
mbed_official 0:51ac1d130fd4 52 static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
mbed_official 0:51ac1d130fd4 53 static long randCount = 0; /* Pseudo-random incrementer */
mbed_official 0:51ac1d130fd4 54
mbed_official 0:51ac1d130fd4 55
mbed_official 0:51ac1d130fd4 56 /***********************************/
mbed_official 0:51ac1d130fd4 57 /*** PUBLIC FUNCTION DEFINITIONS ***/
mbed_official 0:51ac1d130fd4 58 /***********************************/
mbed_official 0:51ac1d130fd4 59 /*
mbed_official 0:51ac1d130fd4 60 * Initialize the random number generator.
mbed_official 0:51ac1d130fd4 61 *
mbed_official 0:51ac1d130fd4 62 * Since this is to be called on power up, we don't have much
mbed_official 0:51ac1d130fd4 63 * system randomess to work with. Here all we use is the
mbed_official 0:51ac1d130fd4 64 * real-time clock. We'll accumulate more randomness as soon
mbed_official 0:51ac1d130fd4 65 * as things start happening.
mbed_official 0:51ac1d130fd4 66 */
mbed_official 0:51ac1d130fd4 67 void
mbed_official 0:51ac1d130fd4 68 avRandomInit()
mbed_official 0:51ac1d130fd4 69 {
mbed_official 0:51ac1d130fd4 70 avChurnRand(NULL, 0);
mbed_official 0:51ac1d130fd4 71 }
mbed_official 0:51ac1d130fd4 72
mbed_official 0:51ac1d130fd4 73 /*
mbed_official 0:51ac1d130fd4 74 * Churn the randomness pool on a random event. Call this early and often
mbed_official 0:51ac1d130fd4 75 * on random and semi-random system events to build randomness in time for
mbed_official 0:51ac1d130fd4 76 * usage. For randomly timed events, pass a null pointer and a zero length
mbed_official 0:51ac1d130fd4 77 * and this will use the system timer and other sources to add randomness.
mbed_official 0:51ac1d130fd4 78 * If new random data is available, pass a pointer to that and it will be
mbed_official 0:51ac1d130fd4 79 * included.
mbed_official 0:51ac1d130fd4 80 *
mbed_official 0:51ac1d130fd4 81 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
mbed_official 0:51ac1d130fd4 82 */
mbed_official 0:51ac1d130fd4 83 void
mbed_official 0:51ac1d130fd4 84 avChurnRand(char *randData, u32_t randLen)
mbed_official 0:51ac1d130fd4 85 {
mbed_official 0:51ac1d130fd4 86 MD5_CTX md5;
mbed_official 0:51ac1d130fd4 87
mbed_official 0:51ac1d130fd4 88 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
mbed_official 0:51ac1d130fd4 89 MD5Init(&md5);
mbed_official 0:51ac1d130fd4 90 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
mbed_official 0:51ac1d130fd4 91 if (randData) {
mbed_official 0:51ac1d130fd4 92 MD5Update(&md5, (u_char *)randData, randLen);
mbed_official 0:51ac1d130fd4 93 } else {
mbed_official 0:51ac1d130fd4 94 struct {
mbed_official 0:51ac1d130fd4 95 /* INCLUDE fields for any system sources of randomness */
mbed_official 0:51ac1d130fd4 96 char foobar;
mbed_official 0:51ac1d130fd4 97 } sysData;
mbed_official 0:51ac1d130fd4 98
mbed_official 0:51ac1d130fd4 99 /* Load sysData fields here. */
mbed_official 0:51ac1d130fd4 100 MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
mbed_official 0:51ac1d130fd4 101 }
mbed_official 0:51ac1d130fd4 102 MD5Final((u_char *)randPool, &md5);
mbed_official 0:51ac1d130fd4 103 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
mbed_official 0:51ac1d130fd4 104 }
mbed_official 0:51ac1d130fd4 105
mbed_official 0:51ac1d130fd4 106 /*
mbed_official 0:51ac1d130fd4 107 * Use the random pool to generate random data. This degrades to pseudo
mbed_official 0:51ac1d130fd4 108 * random when used faster than randomness is supplied using churnRand().
mbed_official 0:51ac1d130fd4 109 * Note: It's important that there be sufficient randomness in randPool
mbed_official 0:51ac1d130fd4 110 * before this is called for otherwise the range of the result may be
mbed_official 0:51ac1d130fd4 111 * narrow enough to make a search feasible.
mbed_official 0:51ac1d130fd4 112 *
mbed_official 0:51ac1d130fd4 113 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
mbed_official 0:51ac1d130fd4 114 *
mbed_official 0:51ac1d130fd4 115 * XXX Why does he not just call churnRand() for each block? Probably
mbed_official 0:51ac1d130fd4 116 * so that you don't ever publish the seed which could possibly help
mbed_official 0:51ac1d130fd4 117 * predict future values.
mbed_official 0:51ac1d130fd4 118 * XXX Why don't we preserve md5 between blocks and just update it with
mbed_official 0:51ac1d130fd4 119 * randCount each time? Probably there is a weakness but I wish that
mbed_official 0:51ac1d130fd4 120 * it was documented.
mbed_official 0:51ac1d130fd4 121 */
mbed_official 0:51ac1d130fd4 122 void
mbed_official 0:51ac1d130fd4 123 avGenRand(char *buf, u32_t bufLen)
mbed_official 0:51ac1d130fd4 124 {
mbed_official 0:51ac1d130fd4 125 MD5_CTX md5;
mbed_official 0:51ac1d130fd4 126 u_char tmp[16];
mbed_official 0:51ac1d130fd4 127 u32_t n;
mbed_official 0:51ac1d130fd4 128
mbed_official 0:51ac1d130fd4 129 while (bufLen > 0) {
mbed_official 0:51ac1d130fd4 130 n = LWIP_MIN(bufLen, RANDPOOLSZ);
mbed_official 0:51ac1d130fd4 131 MD5Init(&md5);
mbed_official 0:51ac1d130fd4 132 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
mbed_official 0:51ac1d130fd4 133 MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
mbed_official 0:51ac1d130fd4 134 MD5Final(tmp, &md5);
mbed_official 0:51ac1d130fd4 135 randCount++;
mbed_official 0:51ac1d130fd4 136 MEMCPY(buf, tmp, n);
mbed_official 0:51ac1d130fd4 137 buf += n;
mbed_official 0:51ac1d130fd4 138 bufLen -= n;
mbed_official 0:51ac1d130fd4 139 }
mbed_official 0:51ac1d130fd4 140 }
mbed_official 0:51ac1d130fd4 141
mbed_official 0:51ac1d130fd4 142 /*
mbed_official 0:51ac1d130fd4 143 * Return a new random number.
mbed_official 0:51ac1d130fd4 144 */
mbed_official 0:51ac1d130fd4 145 u32_t
mbed_official 0:51ac1d130fd4 146 avRandom()
mbed_official 0:51ac1d130fd4 147 {
mbed_official 0:51ac1d130fd4 148 u32_t newRand;
mbed_official 0:51ac1d130fd4 149
mbed_official 0:51ac1d130fd4 150 avGenRand((char *)&newRand, sizeof(newRand));
mbed_official 0:51ac1d130fd4 151
mbed_official 0:51ac1d130fd4 152 return newRand;
mbed_official 0:51ac1d130fd4 153 }
mbed_official 0:51ac1d130fd4 154
mbed_official 0:51ac1d130fd4 155 #else /* MD5_SUPPORT */
mbed_official 0:51ac1d130fd4 156
mbed_official 0:51ac1d130fd4 157 /*****************************/
mbed_official 0:51ac1d130fd4 158 /*** LOCAL DATA STRUCTURES ***/
mbed_official 0:51ac1d130fd4 159 /*****************************/
mbed_official 0:51ac1d130fd4 160 static int avRandomized = 0; /* Set when truely randomized. */
mbed_official 0:51ac1d130fd4 161 static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
mbed_official 0:51ac1d130fd4 162
mbed_official 0:51ac1d130fd4 163
mbed_official 0:51ac1d130fd4 164 /***********************************/
mbed_official 0:51ac1d130fd4 165 /*** PUBLIC FUNCTION DEFINITIONS ***/
mbed_official 0:51ac1d130fd4 166 /***********************************/
mbed_official 0:51ac1d130fd4 167 /*
mbed_official 0:51ac1d130fd4 168 * Initialize the random number generator.
mbed_official 0:51ac1d130fd4 169 *
mbed_official 0:51ac1d130fd4 170 * Here we attempt to compute a random number seed but even if
mbed_official 0:51ac1d130fd4 171 * it isn't random, we'll randomize it later.
mbed_official 0:51ac1d130fd4 172 *
mbed_official 0:51ac1d130fd4 173 * The current method uses the fields from the real time clock,
mbed_official 0:51ac1d130fd4 174 * the idle process counter, the millisecond counter, and the
mbed_official 0:51ac1d130fd4 175 * hardware timer tick counter. When this is invoked
mbed_official 0:51ac1d130fd4 176 * in startup(), then the idle counter and timer values may
mbed_official 0:51ac1d130fd4 177 * repeat after each boot and the real time clock may not be
mbed_official 0:51ac1d130fd4 178 * operational. Thus we call it again on the first random
mbed_official 0:51ac1d130fd4 179 * event.
mbed_official 0:51ac1d130fd4 180 */
mbed_official 0:51ac1d130fd4 181 void
mbed_official 0:51ac1d130fd4 182 avRandomInit()
mbed_official 0:51ac1d130fd4 183 {
mbed_official 0:51ac1d130fd4 184 #if 0
mbed_official 0:51ac1d130fd4 185 /* Get a pointer into the last 4 bytes of clockBuf. */
mbed_official 0:51ac1d130fd4 186 u32_t *lptr1 = (u32_t *)((char *)&clockBuf[3]);
mbed_official 0:51ac1d130fd4 187
mbed_official 0:51ac1d130fd4 188 /*
mbed_official 0:51ac1d130fd4 189 * Initialize our seed using the real-time clock, the idle
mbed_official 0:51ac1d130fd4 190 * counter, the millisecond timer, and the hardware timer
mbed_official 0:51ac1d130fd4 191 * tick counter. The real-time clock and the hardware
mbed_official 0:51ac1d130fd4 192 * tick counter are the best sources of randomness but
mbed_official 0:51ac1d130fd4 193 * since the tick counter is only 16 bit (and truncated
mbed_official 0:51ac1d130fd4 194 * at that), the idle counter and millisecond timer
mbed_official 0:51ac1d130fd4 195 * (which may be small values) are added to help
mbed_official 0:51ac1d130fd4 196 * randomize the lower 16 bits of the seed.
mbed_official 0:51ac1d130fd4 197 */
mbed_official 0:51ac1d130fd4 198 readClk();
mbed_official 0:51ac1d130fd4 199 avRandomSeed += *(u32_t *)clockBuf + *lptr1 + OSIdleCtr
mbed_official 0:51ac1d130fd4 200 + ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
mbed_official 0:51ac1d130fd4 201 #else
mbed_official 0:51ac1d130fd4 202 avRandomSeed += sys_jiffies(); /* XXX */
mbed_official 0:51ac1d130fd4 203 #endif
mbed_official 0:51ac1d130fd4 204
mbed_official 0:51ac1d130fd4 205 /* Initialize the Borland random number generator. */
mbed_official 0:51ac1d130fd4 206 srand((unsigned)avRandomSeed);
mbed_official 0:51ac1d130fd4 207 }
mbed_official 0:51ac1d130fd4 208
mbed_official 0:51ac1d130fd4 209 /*
mbed_official 0:51ac1d130fd4 210 * Randomize our random seed value. Here we use the fact that
mbed_official 0:51ac1d130fd4 211 * this function is called at *truely random* times by the polling
mbed_official 0:51ac1d130fd4 212 * and network functions. Here we only get 16 bits of new random
mbed_official 0:51ac1d130fd4 213 * value but we use the previous value to randomize the other 16
mbed_official 0:51ac1d130fd4 214 * bits.
mbed_official 0:51ac1d130fd4 215 */
mbed_official 0:51ac1d130fd4 216 void
mbed_official 0:51ac1d130fd4 217 avRandomize(void)
mbed_official 0:51ac1d130fd4 218 {
mbed_official 0:51ac1d130fd4 219 static u32_t last_jiffies;
mbed_official 0:51ac1d130fd4 220
mbed_official 0:51ac1d130fd4 221 if (!avRandomized) {
mbed_official 0:51ac1d130fd4 222 avRandomized = !0;
mbed_official 0:51ac1d130fd4 223 avRandomInit();
mbed_official 0:51ac1d130fd4 224 /* The initialization function also updates the seed. */
mbed_official 0:51ac1d130fd4 225 } else {
mbed_official 0:51ac1d130fd4 226 /* avRandomSeed += (avRandomSeed << 16) + TM1; */
mbed_official 0:51ac1d130fd4 227 avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
mbed_official 0:51ac1d130fd4 228 }
mbed_official 0:51ac1d130fd4 229 last_jiffies = sys_jiffies();
mbed_official 0:51ac1d130fd4 230 }
mbed_official 0:51ac1d130fd4 231
mbed_official 0:51ac1d130fd4 232 /*
mbed_official 0:51ac1d130fd4 233 * Return a new random number.
mbed_official 0:51ac1d130fd4 234 * Here we use the Borland rand() function to supply a pseudo random
mbed_official 0:51ac1d130fd4 235 * number which we make truely random by combining it with our own
mbed_official 0:51ac1d130fd4 236 * seed which is randomized by truely random events.
mbed_official 0:51ac1d130fd4 237 * Thus the numbers will be truely random unless there have been no
mbed_official 0:51ac1d130fd4 238 * operator or network events in which case it will be pseudo random
mbed_official 0:51ac1d130fd4 239 * seeded by the real time clock.
mbed_official 0:51ac1d130fd4 240 */
mbed_official 0:51ac1d130fd4 241 u32_t
mbed_official 0:51ac1d130fd4 242 avRandom()
mbed_official 0:51ac1d130fd4 243 {
mbed_official 0:51ac1d130fd4 244 return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
mbed_official 0:51ac1d130fd4 245 }
mbed_official 0:51ac1d130fd4 246
mbed_official 0:51ac1d130fd4 247 #endif /* MD5_SUPPORT */
mbed_official 0:51ac1d130fd4 248
mbed_official 0:51ac1d130fd4 249 #endif /* PPP_SUPPORT */