Sam Walsh / F7_Ethernet_F746ZG

Forked from the DieterGraef Library

Fork of F7_Ethernet by Dieter Graef

lwip/netif/ppp/randm.c@0:d26c1b55cfca, 2016-06-19 (annotated)

Committer:
DieterGraef
Date:
Sun Jun 19 16:23:40 2016 +0000
Revision:
0:d26c1b55cfca
Ethernet Library for Nucleo stm32f746ZG and Disco stm32f746NG  works under arm and gcc environment

Who changed what in which revision?

UserRevisionLine numberNew contents of line
DieterGraef 0:d26c1b55cfca 1 /*****************************************************************************
DieterGraef 0:d26c1b55cfca 2 * randm.c - Random number generator program file.
DieterGraef 0:d26c1b55cfca 3 *
DieterGraef 0:d26c1b55cfca 4 * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
DieterGraef 0:d26c1b55cfca 5 * Copyright (c) 1998 by Global Election Systems Inc.
DieterGraef 0:d26c1b55cfca 6 *
DieterGraef 0:d26c1b55cfca 7 * The authors hereby grant permission to use, copy, modify, distribute,
DieterGraef 0:d26c1b55cfca 8 * and license this software and its documentation for any purpose, provided
DieterGraef 0:d26c1b55cfca 9 * that existing copyright notices are retained in all copies and that this
DieterGraef 0:d26c1b55cfca 10 * notice and the following disclaimer are included verbatim in any
DieterGraef 0:d26c1b55cfca 11 * distributions. No written agreement, license, or royalty fee is required
DieterGraef 0:d26c1b55cfca 12 * for any of the authorized uses.
DieterGraef 0:d26c1b55cfca 13 *
DieterGraef 0:d26c1b55cfca 14 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
DieterGraef 0:d26c1b55cfca 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
DieterGraef 0:d26c1b55cfca 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
DieterGraef 0:d26c1b55cfca 17 * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
DieterGraef 0:d26c1b55cfca 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
DieterGraef 0:d26c1b55cfca 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DieterGraef 0:d26c1b55cfca 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
DieterGraef 0:d26c1b55cfca 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
DieterGraef 0:d26c1b55cfca 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
DieterGraef 0:d26c1b55cfca 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
DieterGraef 0:d26c1b55cfca 24 *
DieterGraef 0:d26c1b55cfca 25 ******************************************************************************
DieterGraef 0:d26c1b55cfca 26 * REVISION HISTORY
DieterGraef 0:d26c1b55cfca 27 *
DieterGraef 0:d26c1b55cfca 28 * 03-01-01 Marc Boucher <marc@mbsi.ca>
DieterGraef 0:d26c1b55cfca 29 * Ported to lwIP.
DieterGraef 0:d26c1b55cfca 30 * 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
DieterGraef 0:d26c1b55cfca 31 * Extracted from avos.
DieterGraef 0:d26c1b55cfca 32 *****************************************************************************/
DieterGraef 0:d26c1b55cfca 33
DieterGraef 0:d26c1b55cfca 34 #include "lwip/opt.h"
DieterGraef 0:d26c1b55cfca 35
DieterGraef 0:d26c1b55cfca 36 #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
DieterGraef 0:d26c1b55cfca 37
DieterGraef 0:d26c1b55cfca 38 #include "md5.h"
DieterGraef 0:d26c1b55cfca 39 #include "randm.h"
DieterGraef 0:d26c1b55cfca 40
DieterGraef 0:d26c1b55cfca 41 #include "ppp_impl.h"
DieterGraef 0:d26c1b55cfca 42 #include "pppdebug.h"
DieterGraef 0:d26c1b55cfca 43
DieterGraef 0:d26c1b55cfca 44 #include <string.h>
DieterGraef 0:d26c1b55cfca 45
DieterGraef 0:d26c1b55cfca 46 #if MD5_SUPPORT /* this module depends on MD5 */
DieterGraef 0:d26c1b55cfca 47 #define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
DieterGraef 0:d26c1b55cfca 48
DieterGraef 0:d26c1b55cfca 49 /*****************************/
DieterGraef 0:d26c1b55cfca 50 /*** LOCAL DATA STRUCTURES ***/
DieterGraef 0:d26c1b55cfca 51 /*****************************/
DieterGraef 0:d26c1b55cfca 52 static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
DieterGraef 0:d26c1b55cfca 53 static long randCount = 0; /* Pseudo-random incrementer */
DieterGraef 0:d26c1b55cfca 54
DieterGraef 0:d26c1b55cfca 55
DieterGraef 0:d26c1b55cfca 56 /***********************************/
DieterGraef 0:d26c1b55cfca 57 /*** PUBLIC FUNCTION DEFINITIONS ***/
DieterGraef 0:d26c1b55cfca 58 /***********************************/
DieterGraef 0:d26c1b55cfca 59 /*
DieterGraef 0:d26c1b55cfca 60 * Initialize the random number generator.
DieterGraef 0:d26c1b55cfca 61 *
DieterGraef 0:d26c1b55cfca 62 * Since this is to be called on power up, we don't have much
DieterGraef 0:d26c1b55cfca 63 * system randomess to work with. Here all we use is the
DieterGraef 0:d26c1b55cfca 64 * real-time clock. We'll accumulate more randomness as soon
DieterGraef 0:d26c1b55cfca 65 * as things start happening.
DieterGraef 0:d26c1b55cfca 66 */
DieterGraef 0:d26c1b55cfca 67 void
DieterGraef 0:d26c1b55cfca 68 avRandomInit()
DieterGraef 0:d26c1b55cfca 69 {
DieterGraef 0:d26c1b55cfca 70 avChurnRand(NULL, 0);
DieterGraef 0:d26c1b55cfca 71 }
DieterGraef 0:d26c1b55cfca 72
DieterGraef 0:d26c1b55cfca 73 /*
DieterGraef 0:d26c1b55cfca 74 * Churn the randomness pool on a random event. Call this early and often
DieterGraef 0:d26c1b55cfca 75 * on random and semi-random system events to build randomness in time for
DieterGraef 0:d26c1b55cfca 76 * usage. For randomly timed events, pass a null pointer and a zero length
DieterGraef 0:d26c1b55cfca 77 * and this will use the system timer and other sources to add randomness.
DieterGraef 0:d26c1b55cfca 78 * If new random data is available, pass a pointer to that and it will be
DieterGraef 0:d26c1b55cfca 79 * included.
DieterGraef 0:d26c1b55cfca 80 *
DieterGraef 0:d26c1b55cfca 81 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
DieterGraef 0:d26c1b55cfca 82 */
DieterGraef 0:d26c1b55cfca 83 void
DieterGraef 0:d26c1b55cfca 84 avChurnRand(char *randData, u32_t randLen)
DieterGraef 0:d26c1b55cfca 85 {
DieterGraef 0:d26c1b55cfca 86 MD5_CTX md5;
DieterGraef 0:d26c1b55cfca 87
DieterGraef 0:d26c1b55cfca 88 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
DieterGraef 0:d26c1b55cfca 89 MD5Init(&md5);
DieterGraef 0:d26c1b55cfca 90 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
DieterGraef 0:d26c1b55cfca 91 if (randData) {
DieterGraef 0:d26c1b55cfca 92 MD5Update(&md5, (u_char *)randData, randLen);
DieterGraef 0:d26c1b55cfca 93 } else {
DieterGraef 0:d26c1b55cfca 94 struct {
DieterGraef 0:d26c1b55cfca 95 /* INCLUDE fields for any system sources of randomness */
DieterGraef 0:d26c1b55cfca 96 char foobar;
DieterGraef 0:d26c1b55cfca 97 } sysData;
DieterGraef 0:d26c1b55cfca 98
DieterGraef 0:d26c1b55cfca 99 /* Load sysData fields here. */
DieterGraef 0:d26c1b55cfca 100 MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
DieterGraef 0:d26c1b55cfca 101 }
DieterGraef 0:d26c1b55cfca 102 MD5Final((u_char *)randPool, &md5);
DieterGraef 0:d26c1b55cfca 103 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
DieterGraef 0:d26c1b55cfca 104 }
DieterGraef 0:d26c1b55cfca 105
DieterGraef 0:d26c1b55cfca 106 /*
DieterGraef 0:d26c1b55cfca 107 * Use the random pool to generate random data. This degrades to pseudo
DieterGraef 0:d26c1b55cfca 108 * random when used faster than randomness is supplied using churnRand().
DieterGraef 0:d26c1b55cfca 109 * Note: It's important that there be sufficient randomness in randPool
DieterGraef 0:d26c1b55cfca 110 * before this is called for otherwise the range of the result may be
DieterGraef 0:d26c1b55cfca 111 * narrow enough to make a search feasible.
DieterGraef 0:d26c1b55cfca 112 *
DieterGraef 0:d26c1b55cfca 113 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
DieterGraef 0:d26c1b55cfca 114 *
DieterGraef 0:d26c1b55cfca 115 * XXX Why does he not just call churnRand() for each block? Probably
DieterGraef 0:d26c1b55cfca 116 * so that you don't ever publish the seed which could possibly help
DieterGraef 0:d26c1b55cfca 117 * predict future values.
DieterGraef 0:d26c1b55cfca 118 * XXX Why don't we preserve md5 between blocks and just update it with
DieterGraef 0:d26c1b55cfca 119 * randCount each time? Probably there is a weakness but I wish that
DieterGraef 0:d26c1b55cfca 120 * it was documented.
DieterGraef 0:d26c1b55cfca 121 */
DieterGraef 0:d26c1b55cfca 122 void
DieterGraef 0:d26c1b55cfca 123 avGenRand(char *buf, u32_t bufLen)
DieterGraef 0:d26c1b55cfca 124 {
DieterGraef 0:d26c1b55cfca 125 MD5_CTX md5;
DieterGraef 0:d26c1b55cfca 126 u_char tmp[16];
DieterGraef 0:d26c1b55cfca 127 u32_t n;
DieterGraef 0:d26c1b55cfca 128
DieterGraef 0:d26c1b55cfca 129 while (bufLen > 0) {
DieterGraef 0:d26c1b55cfca 130 n = LWIP_MIN(bufLen, RANDPOOLSZ);
DieterGraef 0:d26c1b55cfca 131 MD5Init(&md5);
DieterGraef 0:d26c1b55cfca 132 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
DieterGraef 0:d26c1b55cfca 133 MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
DieterGraef 0:d26c1b55cfca 134 MD5Final(tmp, &md5);
DieterGraef 0:d26c1b55cfca 135 randCount++;
DieterGraef 0:d26c1b55cfca 136 MEMCPY(buf, tmp, n);
DieterGraef 0:d26c1b55cfca 137 buf += n;
DieterGraef 0:d26c1b55cfca 138 bufLen -= n;
DieterGraef 0:d26c1b55cfca 139 }
DieterGraef 0:d26c1b55cfca 140 }
DieterGraef 0:d26c1b55cfca 141
DieterGraef 0:d26c1b55cfca 142 /*
DieterGraef 0:d26c1b55cfca 143 * Return a new random number.
DieterGraef 0:d26c1b55cfca 144 */
DieterGraef 0:d26c1b55cfca 145 u32_t
DieterGraef 0:d26c1b55cfca 146 avRandom()
DieterGraef 0:d26c1b55cfca 147 {
DieterGraef 0:d26c1b55cfca 148 u32_t newRand;
DieterGraef 0:d26c1b55cfca 149
DieterGraef 0:d26c1b55cfca 150 avGenRand((char *)&newRand, sizeof(newRand));
DieterGraef 0:d26c1b55cfca 151
DieterGraef 0:d26c1b55cfca 152 return newRand;
DieterGraef 0:d26c1b55cfca 153 }
DieterGraef 0:d26c1b55cfca 154
DieterGraef 0:d26c1b55cfca 155 #else /* MD5_SUPPORT */
DieterGraef 0:d26c1b55cfca 156
DieterGraef 0:d26c1b55cfca 157 /*****************************/
DieterGraef 0:d26c1b55cfca 158 /*** LOCAL DATA STRUCTURES ***/
DieterGraef 0:d26c1b55cfca 159 /*****************************/
DieterGraef 0:d26c1b55cfca 160 static int avRandomized = 0; /* Set when truely randomized. */
DieterGraef 0:d26c1b55cfca 161 static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
DieterGraef 0:d26c1b55cfca 162
DieterGraef 0:d26c1b55cfca 163
DieterGraef 0:d26c1b55cfca 164 /***********************************/
DieterGraef 0:d26c1b55cfca 165 /*** PUBLIC FUNCTION DEFINITIONS ***/
DieterGraef 0:d26c1b55cfca 166 /***********************************/
DieterGraef 0:d26c1b55cfca 167 /*
DieterGraef 0:d26c1b55cfca 168 * Initialize the random number generator.
DieterGraef 0:d26c1b55cfca 169 *
DieterGraef 0:d26c1b55cfca 170 * Here we attempt to compute a random number seed but even if
DieterGraef 0:d26c1b55cfca 171 * it isn't random, we'll randomize it later.
DieterGraef 0:d26c1b55cfca 172 *
DieterGraef 0:d26c1b55cfca 173 * The current method uses the fields from the real time clock,
DieterGraef 0:d26c1b55cfca 174 * the idle process counter, the millisecond counter, and the
DieterGraef 0:d26c1b55cfca 175 * hardware timer tick counter. When this is invoked
DieterGraef 0:d26c1b55cfca 176 * in startup(), then the idle counter and timer values may
DieterGraef 0:d26c1b55cfca 177 * repeat after each boot and the real time clock may not be
DieterGraef 0:d26c1b55cfca 178 * operational. Thus we call it again on the first random
DieterGraef 0:d26c1b55cfca 179 * event.
DieterGraef 0:d26c1b55cfca 180 */
DieterGraef 0:d26c1b55cfca 181 void
DieterGraef 0:d26c1b55cfca 182 avRandomInit()
DieterGraef 0:d26c1b55cfca 183 {
DieterGraef 0:d26c1b55cfca 184 #if 0
DieterGraef 0:d26c1b55cfca 185 /* Get a pointer into the last 4 bytes of clockBuf. */
DieterGraef 0:d26c1b55cfca 186 u32_t *lptr1 = (u32_t *)((char *)&clockBuf[3]);
DieterGraef 0:d26c1b55cfca 187
DieterGraef 0:d26c1b55cfca 188 /*
DieterGraef 0:d26c1b55cfca 189 * Initialize our seed using the real-time clock, the idle
DieterGraef 0:d26c1b55cfca 190 * counter, the millisecond timer, and the hardware timer
DieterGraef 0:d26c1b55cfca 191 * tick counter. The real-time clock and the hardware
DieterGraef 0:d26c1b55cfca 192 * tick counter are the best sources of randomness but
DieterGraef 0:d26c1b55cfca 193 * since the tick counter is only 16 bit (and truncated
DieterGraef 0:d26c1b55cfca 194 * at that), the idle counter and millisecond timer
DieterGraef 0:d26c1b55cfca 195 * (which may be small values) are added to help
DieterGraef 0:d26c1b55cfca 196 * randomize the lower 16 bits of the seed.
DieterGraef 0:d26c1b55cfca 197 */
DieterGraef 0:d26c1b55cfca 198 readClk();
DieterGraef 0:d26c1b55cfca 199 avRandomSeed += *(u32_t *)clockBuf + *lptr1 + OSIdleCtr
DieterGraef 0:d26c1b55cfca 200 + ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
DieterGraef 0:d26c1b55cfca 201 #else
DieterGraef 0:d26c1b55cfca 202 avRandomSeed += sys_jiffies(); /* XXX */
DieterGraef 0:d26c1b55cfca 203 #endif
DieterGraef 0:d26c1b55cfca 204
DieterGraef 0:d26c1b55cfca 205 /* Initialize the Borland random number generator. */
DieterGraef 0:d26c1b55cfca 206 srand((unsigned)avRandomSeed);
DieterGraef 0:d26c1b55cfca 207 }
DieterGraef 0:d26c1b55cfca 208
DieterGraef 0:d26c1b55cfca 209 /*
DieterGraef 0:d26c1b55cfca 210 * Randomize our random seed value. Here we use the fact that
DieterGraef 0:d26c1b55cfca 211 * this function is called at *truely random* times by the polling
DieterGraef 0:d26c1b55cfca 212 * and network functions. Here we only get 16 bits of new random
DieterGraef 0:d26c1b55cfca 213 * value but we use the previous value to randomize the other 16
DieterGraef 0:d26c1b55cfca 214 * bits.
DieterGraef 0:d26c1b55cfca 215 */
DieterGraef 0:d26c1b55cfca 216 void
DieterGraef 0:d26c1b55cfca 217 avRandomize(void)
DieterGraef 0:d26c1b55cfca 218 {
DieterGraef 0:d26c1b55cfca 219 static u32_t last_jiffies;
DieterGraef 0:d26c1b55cfca 220
DieterGraef 0:d26c1b55cfca 221 if (!avRandomized) {
DieterGraef 0:d26c1b55cfca 222 avRandomized = !0;
DieterGraef 0:d26c1b55cfca 223 avRandomInit();
DieterGraef 0:d26c1b55cfca 224 /* The initialization function also updates the seed. */
DieterGraef 0:d26c1b55cfca 225 } else {
DieterGraef 0:d26c1b55cfca 226 /* avRandomSeed += (avRandomSeed << 16) + TM1; */
DieterGraef 0:d26c1b55cfca 227 avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
DieterGraef 0:d26c1b55cfca 228 }
DieterGraef 0:d26c1b55cfca 229 last_jiffies = sys_jiffies();
DieterGraef 0:d26c1b55cfca 230 }
DieterGraef 0:d26c1b55cfca 231
DieterGraef 0:d26c1b55cfca 232 /*
DieterGraef 0:d26c1b55cfca 233 * Return a new random number.
DieterGraef 0:d26c1b55cfca 234 * Here we use the Borland rand() function to supply a pseudo random
DieterGraef 0:d26c1b55cfca 235 * number which we make truely random by combining it with our own
DieterGraef 0:d26c1b55cfca 236 * seed which is randomized by truely random events.
DieterGraef 0:d26c1b55cfca 237 * Thus the numbers will be truely random unless there have been no
DieterGraef 0:d26c1b55cfca 238 * operator or network events in which case it will be pseudo random
DieterGraef 0:d26c1b55cfca 239 * seeded by the real time clock.
DieterGraef 0:d26c1b55cfca 240 */
DieterGraef 0:d26c1b55cfca 241 u32_t
DieterGraef 0:d26c1b55cfca 242 avRandom()
DieterGraef 0:d26c1b55cfca 243 {
DieterGraef 0:d26c1b55cfca 244 return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
DieterGraef 0:d26c1b55cfca 245 }
DieterGraef 0:d26c1b55cfca 246
DieterGraef 0:d26c1b55cfca 247 #endif /* MD5_SUPPORT */
DieterGraef 0:d26c1b55cfca 248
DieterGraef 0:d26c1b55cfca 249 #endif /* PPP_SUPPORT */