孙 毅明 / Mbed 2 deprecated 123

创建mbed

Dependencies:   EthernetInterface SDFileSystem mbed-rtos mbed

EthernetInterface/lwip/netif/ppp/randm.c@1:6465a3f5c58a, 2018-03-06 (annotated)

Committer:
sunyiming
Date:
Tue Mar 06 08:53:46 2018 +0000
Revision:
1:6465a3f5c58a
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Who changed what in which revision?

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sunyiming 1:6465a3f5c58a 1 /*****************************************************************************
sunyiming 1:6465a3f5c58a 2 * randm.c - Random number generator program file.
sunyiming 1:6465a3f5c58a 3 *
sunyiming 1:6465a3f5c58a 4 * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
sunyiming 1:6465a3f5c58a 5 * Copyright (c) 1998 by Global Election Systems Inc.
sunyiming 1:6465a3f5c58a 6 *
sunyiming 1:6465a3f5c58a 7 * The authors hereby grant permission to use, copy, modify, distribute,
sunyiming 1:6465a3f5c58a 8 * and license this software and its documentation for any purpose, provided
sunyiming 1:6465a3f5c58a 9 * that existing copyright notices are retained in all copies and that this
sunyiming 1:6465a3f5c58a 10 * notice and the following disclaimer are included verbatim in any
sunyiming 1:6465a3f5c58a 11 * distributions. No written agreement, license, or royalty fee is required
sunyiming 1:6465a3f5c58a 12 * for any of the authorized uses.
sunyiming 1:6465a3f5c58a 13 *
sunyiming 1:6465a3f5c58a 14 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
sunyiming 1:6465a3f5c58a 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
sunyiming 1:6465a3f5c58a 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
sunyiming 1:6465a3f5c58a 17 * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
sunyiming 1:6465a3f5c58a 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
sunyiming 1:6465a3f5c58a 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
sunyiming 1:6465a3f5c58a 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
sunyiming 1:6465a3f5c58a 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
sunyiming 1:6465a3f5c58a 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
sunyiming 1:6465a3f5c58a 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
sunyiming 1:6465a3f5c58a 24 *
sunyiming 1:6465a3f5c58a 25 ******************************************************************************
sunyiming 1:6465a3f5c58a 26 * REVISION HISTORY
sunyiming 1:6465a3f5c58a 27 *
sunyiming 1:6465a3f5c58a 28 * 03-01-01 Marc Boucher <marc@mbsi.ca>
sunyiming 1:6465a3f5c58a 29 * Ported to lwIP.
sunyiming 1:6465a3f5c58a 30 * 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
sunyiming 1:6465a3f5c58a 31 * Extracted from avos.
sunyiming 1:6465a3f5c58a 32 *****************************************************************************/
sunyiming 1:6465a3f5c58a 33
sunyiming 1:6465a3f5c58a 34 #include "lwip/opt.h"
sunyiming 1:6465a3f5c58a 35
sunyiming 1:6465a3f5c58a 36 #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
sunyiming 1:6465a3f5c58a 37
sunyiming 1:6465a3f5c58a 38 #include "md5.h"
sunyiming 1:6465a3f5c58a 39 #include "randm.h"
sunyiming 1:6465a3f5c58a 40
sunyiming 1:6465a3f5c58a 41 #include "ppp.h"
sunyiming 1:6465a3f5c58a 42 #include "pppdebug.h"
sunyiming 1:6465a3f5c58a 43
sunyiming 1:6465a3f5c58a 44 #include <string.h>
sunyiming 1:6465a3f5c58a 45
sunyiming 1:6465a3f5c58a 46 #if MD5_SUPPORT /* this module depends on MD5 */
sunyiming 1:6465a3f5c58a 47 #define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
sunyiming 1:6465a3f5c58a 48
sunyiming 1:6465a3f5c58a 49 /*****************************/
sunyiming 1:6465a3f5c58a 50 /*** LOCAL DATA STRUCTURES ***/
sunyiming 1:6465a3f5c58a 51 /*****************************/
sunyiming 1:6465a3f5c58a 52 static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
sunyiming 1:6465a3f5c58a 53 static long randCount = 0; /* Pseudo-random incrementer */
sunyiming 1:6465a3f5c58a 54
sunyiming 1:6465a3f5c58a 55
sunyiming 1:6465a3f5c58a 56 /***********************************/
sunyiming 1:6465a3f5c58a 57 /*** PUBLIC FUNCTION DEFINITIONS ***/
sunyiming 1:6465a3f5c58a 58 /***********************************/
sunyiming 1:6465a3f5c58a 59 /*
sunyiming 1:6465a3f5c58a 60 * Initialize the random number generator.
sunyiming 1:6465a3f5c58a 61 *
sunyiming 1:6465a3f5c58a 62 * Since this is to be called on power up, we don't have much
sunyiming 1:6465a3f5c58a 63 * system randomess to work with. Here all we use is the
sunyiming 1:6465a3f5c58a 64 * real-time clock. We'll accumulate more randomness as soon
sunyiming 1:6465a3f5c58a 65 * as things start happening.
sunyiming 1:6465a3f5c58a 66 */
sunyiming 1:6465a3f5c58a 67 void
sunyiming 1:6465a3f5c58a 68 avRandomInit()
sunyiming 1:6465a3f5c58a 69 {
sunyiming 1:6465a3f5c58a 70 avChurnRand(NULL, 0);
sunyiming 1:6465a3f5c58a 71 }
sunyiming 1:6465a3f5c58a 72
sunyiming 1:6465a3f5c58a 73 /*
sunyiming 1:6465a3f5c58a 74 * Churn the randomness pool on a random event. Call this early and often
sunyiming 1:6465a3f5c58a 75 * on random and semi-random system events to build randomness in time for
sunyiming 1:6465a3f5c58a 76 * usage. For randomly timed events, pass a null pointer and a zero length
sunyiming 1:6465a3f5c58a 77 * and this will use the system timer and other sources to add randomness.
sunyiming 1:6465a3f5c58a 78 * If new random data is available, pass a pointer to that and it will be
sunyiming 1:6465a3f5c58a 79 * included.
sunyiming 1:6465a3f5c58a 80 *
sunyiming 1:6465a3f5c58a 81 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
sunyiming 1:6465a3f5c58a 82 */
sunyiming 1:6465a3f5c58a 83 void
sunyiming 1:6465a3f5c58a 84 avChurnRand(char *randData, u32_t randLen)
sunyiming 1:6465a3f5c58a 85 {
sunyiming 1:6465a3f5c58a 86 MD5_CTX md5;
sunyiming 1:6465a3f5c58a 87
sunyiming 1:6465a3f5c58a 88 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
sunyiming 1:6465a3f5c58a 89 MD5Init(&md5);
sunyiming 1:6465a3f5c58a 90 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
sunyiming 1:6465a3f5c58a 91 if (randData) {
sunyiming 1:6465a3f5c58a 92 MD5Update(&md5, (u_char *)randData, randLen);
sunyiming 1:6465a3f5c58a 93 } else {
sunyiming 1:6465a3f5c58a 94 struct {
sunyiming 1:6465a3f5c58a 95 /* INCLUDE fields for any system sources of randomness */
sunyiming 1:6465a3f5c58a 96 char foobar;
sunyiming 1:6465a3f5c58a 97 } sysData;
sunyiming 1:6465a3f5c58a 98
sunyiming 1:6465a3f5c58a 99 /* Load sysData fields here. */
sunyiming 1:6465a3f5c58a 100 MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
sunyiming 1:6465a3f5c58a 101 }
sunyiming 1:6465a3f5c58a 102 MD5Final((u_char *)randPool, &md5);
sunyiming 1:6465a3f5c58a 103 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
sunyiming 1:6465a3f5c58a 104 }
sunyiming 1:6465a3f5c58a 105
sunyiming 1:6465a3f5c58a 106 /*
sunyiming 1:6465a3f5c58a 107 * Use the random pool to generate random data. This degrades to pseudo
sunyiming 1:6465a3f5c58a 108 * random when used faster than randomness is supplied using churnRand().
sunyiming 1:6465a3f5c58a 109 * Note: It's important that there be sufficient randomness in randPool
sunyiming 1:6465a3f5c58a 110 * before this is called for otherwise the range of the result may be
sunyiming 1:6465a3f5c58a 111 * narrow enough to make a search feasible.
sunyiming 1:6465a3f5c58a 112 *
sunyiming 1:6465a3f5c58a 113 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
sunyiming 1:6465a3f5c58a 114 *
sunyiming 1:6465a3f5c58a 115 * XXX Why does he not just call churnRand() for each block? Probably
sunyiming 1:6465a3f5c58a 116 * so that you don't ever publish the seed which could possibly help
sunyiming 1:6465a3f5c58a 117 * predict future values.
sunyiming 1:6465a3f5c58a 118 * XXX Why don't we preserve md5 between blocks and just update it with
sunyiming 1:6465a3f5c58a 119 * randCount each time? Probably there is a weakness but I wish that
sunyiming 1:6465a3f5c58a 120 * it was documented.
sunyiming 1:6465a3f5c58a 121 */
sunyiming 1:6465a3f5c58a 122 void
sunyiming 1:6465a3f5c58a 123 avGenRand(char *buf, u32_t bufLen)
sunyiming 1:6465a3f5c58a 124 {
sunyiming 1:6465a3f5c58a 125 MD5_CTX md5;
sunyiming 1:6465a3f5c58a 126 u_char tmp[16];
sunyiming 1:6465a3f5c58a 127 u32_t n;
sunyiming 1:6465a3f5c58a 128
sunyiming 1:6465a3f5c58a 129 while (bufLen > 0) {
sunyiming 1:6465a3f5c58a 130 n = LWIP_MIN(bufLen, RANDPOOLSZ);
sunyiming 1:6465a3f5c58a 131 MD5Init(&md5);
sunyiming 1:6465a3f5c58a 132 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
sunyiming 1:6465a3f5c58a 133 MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
sunyiming 1:6465a3f5c58a 134 MD5Final(tmp, &md5);
sunyiming 1:6465a3f5c58a 135 randCount++;
sunyiming 1:6465a3f5c58a 136 MEMCPY(buf, tmp, n);
sunyiming 1:6465a3f5c58a 137 buf += n;
sunyiming 1:6465a3f5c58a 138 bufLen -= n;
sunyiming 1:6465a3f5c58a 139 }
sunyiming 1:6465a3f5c58a 140 }
sunyiming 1:6465a3f5c58a 141
sunyiming 1:6465a3f5c58a 142 /*
sunyiming 1:6465a3f5c58a 143 * Return a new random number.
sunyiming 1:6465a3f5c58a 144 */
sunyiming 1:6465a3f5c58a 145 u32_t
sunyiming 1:6465a3f5c58a 146 avRandom()
sunyiming 1:6465a3f5c58a 147 {
sunyiming 1:6465a3f5c58a 148 u32_t newRand;
sunyiming 1:6465a3f5c58a 149
sunyiming 1:6465a3f5c58a 150 avGenRand((char *)&newRand, sizeof(newRand));
sunyiming 1:6465a3f5c58a 151
sunyiming 1:6465a3f5c58a 152 return newRand;
sunyiming 1:6465a3f5c58a 153 }
sunyiming 1:6465a3f5c58a 154
sunyiming 1:6465a3f5c58a 155 #else /* MD5_SUPPORT */
sunyiming 1:6465a3f5c58a 156
sunyiming 1:6465a3f5c58a 157 /*****************************/
sunyiming 1:6465a3f5c58a 158 /*** LOCAL DATA STRUCTURES ***/
sunyiming 1:6465a3f5c58a 159 /*****************************/
sunyiming 1:6465a3f5c58a 160 static int avRandomized = 0; /* Set when truely randomized. */
sunyiming 1:6465a3f5c58a 161 static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
sunyiming 1:6465a3f5c58a 162
sunyiming 1:6465a3f5c58a 163
sunyiming 1:6465a3f5c58a 164 /***********************************/
sunyiming 1:6465a3f5c58a 165 /*** PUBLIC FUNCTION DEFINITIONS ***/
sunyiming 1:6465a3f5c58a 166 /***********************************/
sunyiming 1:6465a3f5c58a 167 /*
sunyiming 1:6465a3f5c58a 168 * Initialize the random number generator.
sunyiming 1:6465a3f5c58a 169 *
sunyiming 1:6465a3f5c58a 170 * Here we attempt to compute a random number seed but even if
sunyiming 1:6465a3f5c58a 171 * it isn't random, we'll randomize it later.
sunyiming 1:6465a3f5c58a 172 *
sunyiming 1:6465a3f5c58a 173 * The current method uses the fields from the real time clock,
sunyiming 1:6465a3f5c58a 174 * the idle process counter, the millisecond counter, and the
sunyiming 1:6465a3f5c58a 175 * hardware timer tick counter. When this is invoked
sunyiming 1:6465a3f5c58a 176 * in startup(), then the idle counter and timer values may
sunyiming 1:6465a3f5c58a 177 * repeat after each boot and the real time clock may not be
sunyiming 1:6465a3f5c58a 178 * operational. Thus we call it again on the first random
sunyiming 1:6465a3f5c58a 179 * event.
sunyiming 1:6465a3f5c58a 180 */
sunyiming 1:6465a3f5c58a 181 void
sunyiming 1:6465a3f5c58a 182 avRandomInit()
sunyiming 1:6465a3f5c58a 183 {
sunyiming 1:6465a3f5c58a 184 #if 0
sunyiming 1:6465a3f5c58a 185 /* Get a pointer into the last 4 bytes of clockBuf. */
sunyiming 1:6465a3f5c58a 186 u32_t *lptr1 = (u32_t *)((char *)&clockBuf[3]);
sunyiming 1:6465a3f5c58a 187
sunyiming 1:6465a3f5c58a 188 /*
sunyiming 1:6465a3f5c58a 189 * Initialize our seed using the real-time clock, the idle
sunyiming 1:6465a3f5c58a 190 * counter, the millisecond timer, and the hardware timer
sunyiming 1:6465a3f5c58a 191 * tick counter. The real-time clock and the hardware
sunyiming 1:6465a3f5c58a 192 * tick counter are the best sources of randomness but
sunyiming 1:6465a3f5c58a 193 * since the tick counter is only 16 bit (and truncated
sunyiming 1:6465a3f5c58a 194 * at that), the idle counter and millisecond timer
sunyiming 1:6465a3f5c58a 195 * (which may be small values) are added to help
sunyiming 1:6465a3f5c58a 196 * randomize the lower 16 bits of the seed.
sunyiming 1:6465a3f5c58a 197 */
sunyiming 1:6465a3f5c58a 198 readClk();
sunyiming 1:6465a3f5c58a 199 avRandomSeed += *(u32_t *)clockBuf + *lptr1 + OSIdleCtr
sunyiming 1:6465a3f5c58a 200 + ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
sunyiming 1:6465a3f5c58a 201 #else
sunyiming 1:6465a3f5c58a 202 avRandomSeed += sys_jiffies(); /* XXX */
sunyiming 1:6465a3f5c58a 203 #endif
sunyiming 1:6465a3f5c58a 204
sunyiming 1:6465a3f5c58a 205 /* Initialize the Borland random number generator. */
sunyiming 1:6465a3f5c58a 206 srand((unsigned)avRandomSeed);
sunyiming 1:6465a3f5c58a 207 }
sunyiming 1:6465a3f5c58a 208
sunyiming 1:6465a3f5c58a 209 /*
sunyiming 1:6465a3f5c58a 210 * Randomize our random seed value. Here we use the fact that
sunyiming 1:6465a3f5c58a 211 * this function is called at *truely random* times by the polling
sunyiming 1:6465a3f5c58a 212 * and network functions. Here we only get 16 bits of new random
sunyiming 1:6465a3f5c58a 213 * value but we use the previous value to randomize the other 16
sunyiming 1:6465a3f5c58a 214 * bits.
sunyiming 1:6465a3f5c58a 215 */
sunyiming 1:6465a3f5c58a 216 void
sunyiming 1:6465a3f5c58a 217 avRandomize(void)
sunyiming 1:6465a3f5c58a 218 {
sunyiming 1:6465a3f5c58a 219 static u32_t last_jiffies;
sunyiming 1:6465a3f5c58a 220
sunyiming 1:6465a3f5c58a 221 if (!avRandomized) {
sunyiming 1:6465a3f5c58a 222 avRandomized = !0;
sunyiming 1:6465a3f5c58a 223 avRandomInit();
sunyiming 1:6465a3f5c58a 224 /* The initialization function also updates the seed. */
sunyiming 1:6465a3f5c58a 225 } else {
sunyiming 1:6465a3f5c58a 226 /* avRandomSeed += (avRandomSeed << 16) + TM1; */
sunyiming 1:6465a3f5c58a 227 avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
sunyiming 1:6465a3f5c58a 228 }
sunyiming 1:6465a3f5c58a 229 last_jiffies = sys_jiffies();
sunyiming 1:6465a3f5c58a 230 }
sunyiming 1:6465a3f5c58a 231
sunyiming 1:6465a3f5c58a 232 /*
sunyiming 1:6465a3f5c58a 233 * Return a new random number.
sunyiming 1:6465a3f5c58a 234 * Here we use the Borland rand() function to supply a pseudo random
sunyiming 1:6465a3f5c58a 235 * number which we make truely random by combining it with our own
sunyiming 1:6465a3f5c58a 236 * seed which is randomized by truely random events.
sunyiming 1:6465a3f5c58a 237 * Thus the numbers will be truely random unless there have been no
sunyiming 1:6465a3f5c58a 238 * operator or network events in which case it will be pseudo random
sunyiming 1:6465a3f5c58a 239 * seeded by the real time clock.
sunyiming 1:6465a3f5c58a 240 */
sunyiming 1:6465a3f5c58a 241 u32_t
sunyiming 1:6465a3f5c58a 242 avRandom()
sunyiming 1:6465a3f5c58a 243 {
sunyiming 1:6465a3f5c58a 244 return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
sunyiming 1:6465a3f5c58a 245 }
sunyiming 1:6465a3f5c58a 246
sunyiming 1:6465a3f5c58a 247 #endif /* MD5_SUPPORT */
sunyiming 1:6465a3f5c58a 248
sunyiming 1:6465a3f5c58a 249 #endif /* PPP_SUPPORT */