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reworked magic/randm

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This commit is contained in:
Sylvain Rochet 2012-05-17 22:42:07 +02:00
parent bcba806ef0
commit 1a1deb5d58
2 changed files with 80 additions and 141 deletions
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168
src/netif/ppp/magic.c
View File

@ -74,7 +74,6 @@
#include "lwip/opt.h" #include "lwip/opt.h"
#define PPP_SUPPORT 1
#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */ #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
#include "md5.h" #include "md5.h"
@ -82,50 +81,21 @@
#include "pppd.h" #include "pppd.h"
#include "pppmy.h" #include "pppmy.h"
/*
* magic_init - Initialize the magic number generator.
*
* Attempts to compute a random number seed which will not repeat.
* The current method uses the current hostid, current process ID
* and current time, currently.
*/
void magic_init() {
avRandomInit();
}
/* #if MD5_SUPPORT /* Using MD5 for better randomness if MD5 support is enabled */
* magic - Returns the next magic number.
*/
u_int32_t magic() {
return (u_int32_t)avRandom();
}
#if MD5_SUPPORT /* this module depends on MD5 */ #define MAGIC_RANDPOOLSIZE 16 /* Bytes stored in the pool of randomness. */
#define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
/*****************************/ /*****************************/
/*** LOCAL DATA STRUCTURES ***/ /*** LOCAL DATA STRUCTURES ***/
/*****************************/ /*****************************/
static char randPool[RANDPOOLSZ]; /* Pool of randomness. */ static char magic_randpool[MAGIC_RANDPOOLSIZE]; /* Pool of randomness. */
static long randCount = 0; /* Pseudo-random incrementer */ static long magic_randcount = 0; /* Pseudo-random incrementer */
/***********************************/ /***********************************/
/*** PUBLIC FUNCTION DEFINITIONS ***/ /*** 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 * Churn the randomness pool on a random event. Call this early and often
@ -137,33 +107,47 @@ avRandomInit()
* *
* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
*/ */
void void magic_churnrand(char *rand_data, u32_t rand_len) {
avChurnRand(char *randData, u32_t randLen)
{
MD5_CTX md5; MD5_CTX md5;
/* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */ /* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", rand_len, rand_data)); */
MD5_Init(&md5); MD5_Init(&md5);
MD5_Update(&md5, (u_char *)randPool, sizeof(randPool)); MD5_Update(&md5, (u_char *)magic_randpool, sizeof(magic_randpool));
if (randData) { if (rand_data) {
MD5_Update(&md5, (u_char *)randData, randLen); MD5_Update(&md5, (u_char *)rand_data, rand_len);
} else { } else {
struct { struct {
/* INCLUDE fields for any system sources of randomness */ /* INCLUDE fields for any system sources of randomness */
char foobar; char foobar;
} sysData; } sys_data;
/* Load sysData fields here. */ /* Load sys_data fields here. */
MD5_Update(&md5, (u_char *)&sysData, sizeof(sysData)); MD5_Update(&md5, (u_char *)&sys_data, sizeof(sys_data));
} }
MD5_Final((u_char *)randPool, &md5); MD5_Final((u_char *)magic_randpool, &md5);
/* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */ /* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
} }
/* /*
* Initialize the random number generator.
*/
void magic_init() {
magic_churnrand(NULL, 0);
}
/*
* Randomize our random seed value.
*/
void magic_randomize(void) {
magic_churnrand(NULL, 0);
}
/*
* random_bytes - Fill a buffer with random bytes.
*
* Use the random pool to generate random data. This degrades to pseudo * Use the random pool to generate random data. This degrades to pseudo
* random when used faster than randomness is supplied using churnRand(). * random when used faster than randomness is supplied using churnRand().
* Note: It's important that there be sufficient randomness in randPool * Note: It's important that there be sufficient randomness in magic_randpool
* before this is called for otherwise the range of the result may be * before this is called for otherwise the range of the result may be
* narrow enough to make a search feasible. * narrow enough to make a search feasible.
* *
@ -173,49 +157,36 @@ avChurnRand(char *randData, u32_t randLen)
* so that you don't ever publish the seed which could possibly help * so that you don't ever publish the seed which could possibly help
* predict future values. * predict future values.
* XXX Why don't we preserve md5 between blocks and just update it with * 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 * magic_randcount each time? Probably there is a weakness but I wish that
* it was documented. * it was documented.
*/ */
void void random_bytes(unsigned char *buf, u32_t buf_len) {
avGenRand(char *buf, u32_t bufLen)
{
MD5_CTX md5; MD5_CTX md5;
u_char tmp[16]; u_char tmp[16];
u32_t n; u32_t n;
while (bufLen > 0) { while (buf_len > 0) {
n = LWIP_MIN(bufLen, RANDPOOLSZ); n = LWIP_MIN(buf_len, MAGIC_RANDPOOLSIZE);
MD5_Init(&md5); MD5_Init(&md5);
MD5_Update(&md5, (u_char *)randPool, sizeof(randPool)); MD5_Update(&md5, (u_char *)magic_randpool, sizeof(magic_randpool));
MD5_Update(&md5, (u_char *)&randCount, sizeof(randCount)); MD5_Update(&md5, (u_char *)&magic_randcount, sizeof(magic_randcount));
MD5_Final(tmp, &md5); MD5_Final(tmp, &md5);
randCount++; magic_randcount++;
MEMCPY(buf, tmp, n); MEMCPY(buf, tmp, n);
buf += n; buf += n;
bufLen -= n; buf_len -= n;
} }
} }
/* /*
* Return a new random number. * Return a new random number.
*/ */
u32_t u32_t magic() {
avRandom() u32_t new_rand;
{
u32_t newRand;
avGenRand((char *)&newRand, sizeof(newRand)); random_bytes((char *)&new_rand, sizeof(new_rand));
return newRand; return new_rand;
}
/*
* random_bytes - Fill a buffer with random bytes.
*/
void
random_bytes(unsigned char *buf, int len)
{
avGenRand(buf, len);
} }
#else /* MD5_SUPPORT */ #else /* MD5_SUPPORT */
@ -223,13 +194,14 @@ random_bytes(unsigned char *buf, int len)
/*****************************/ /*****************************/
/*** LOCAL DATA STRUCTURES ***/ /*** LOCAL DATA STRUCTURES ***/
/*****************************/ /*****************************/
static int avRandomized = 0; /* Set when truely randomized. */ static int magic_randomized = 0; /* Set when truely randomized. */
static u32_t avRandomSeed = 0; /* Seed used for random number generation. */ static u32_t magic_randomseed = 0; /* Seed used for random number generation. */
/***********************************/ /***********************************/
/*** PUBLIC FUNCTION DEFINITIONS ***/ /*** PUBLIC FUNCTION DEFINITIONS ***/
/***********************************/ /***********************************/
/* /*
* Initialize the random number generator. * Initialize the random number generator.
* *
@ -244,59 +216,39 @@ static u32_t avRandomSeed = 0; /* Seed used for random number generation. *
* operational. Thus we call it again on the first random * operational. Thus we call it again on the first random
* event. * event.
*/ */
void void magic_init() {
avRandomInit() magic_randomseed += sys_jiffies();
{
#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. */ /* Initialize the Borland random number generator. */
srand((unsigned)avRandomSeed); srand((unsigned)magic_randomseed);
} }
/* /*
* magic_init - Initialize the magic number generator.
*
* Randomize our random seed value. Here we use the fact that * Randomize our random seed value. Here we use the fact that
* this function is called at *truely random* times by the polling * this function is called at *truely random* times by the polling
* and network functions. Here we only get 16 bits of new random * and network functions. Here we only get 16 bits of new random
* value but we use the previous value to randomize the other 16 * value but we use the previous value to randomize the other 16
* bits. * bits.
*/ */
void void magic_randomize(void) {
avRandomize(void)
{
static u32_t last_jiffies; static u32_t last_jiffies;
if (!avRandomized) { if (!magic_randomized) {
avRandomized = !0; magic_randomized = !0;
avRandomInit(); magic_randominit();
/* The initialization function also updates the seed. */ /* The initialization function also updates the seed. */
} else { } else {
/* avRandomSeed += (avRandomSeed << 16) + TM1; */ /* magic_randomseed += (magic_randomseed << 16) + TM1; */
avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */ magic_randomseed += (sys_jiffies() - last_jiffies); /* XXX */
} }
last_jiffies = sys_jiffies(); last_jiffies = sys_jiffies();
} }
/* /*
* Return a new random number. * Return a new random number.
*
* Here we use the Borland rand() function to supply a pseudo random * Here we use the Borland rand() function to supply a pseudo random
* number which we make truely random by combining it with our own * number which we make truely random by combining it with our own
* seed which is randomized by truely random events. * seed which is randomized by truely random events.
@ -304,10 +256,8 @@ avRandomize(void)
* operator or network events in which case it will be pseudo random * operator or network events in which case it will be pseudo random
* seeded by the real time clock. * seeded by the real time clock.
*/ */
u32_t u32_t magic() {
avRandom() return ((((u32_t)rand() << 16) + rand()) + magic_randomseed);
{
return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
} }
#endif /* MD5_SUPPORT */ #endif /* MD5_SUPPORT */

53
src/netif/ppp/magic.h
View File

@ -74,38 +74,37 @@
* Extracted from avos. * Extracted from avos.
*****************************************************************************/ *****************************************************************************/
#ifndef RANDM_H #ifndef MAGIC_H
#define RANDM_H #define MAGIC_H
#include "lwip/opt.h"
#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
/*********************** /***********************
*** PUBLIC FUNCTIONS *** *** PUBLIC FUNCTIONS ***
***********************/ ***********************/
/* /*
* Initialize the random number generator. * Initialize the random number generator.
*/ */
void avRandomInit(void); void magic_init(void);
/*
* 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.
*/
void avChurnRand(char *randData, u32_t randLen);
/* /*
* Randomize our random seed value. To be called for truely random events * Randomize our random seed value. To be called for truely random events
* such as user operations and network traffic. * such as user operations and network traffic.
*/ */
#if MD5_SUPPORT void magic_randomize(void);
#define avRandomize() avChurnRand(NULL, 0)
#else /* MD5_SUPPORT */
void avRandomize(void);
#endif /* MD5_SUPPORT */
/* /*
* Return a new random number.
*/
u32_t magic(void); /* Returns the next magic number */
#if MD5_SUPPORT
/*
* Fill buffer with random bytes
*
* Use the random pool to generate random data. This degrades to pseudo * Use the random pool to generate random data. This degrades to pseudo
* random when used faster than randomness is supplied using churnRand(). * random when used faster than randomness is supplied using churnRand().
* Thus it's important to make sure that the results of this are not * Thus it's important to make sure that the results of this are not
@ -113,18 +112,8 @@ void avRandomize(void);
* least some degree. Also, it's important to get a good seed before * least some degree. Also, it's important to get a good seed before
* the first use. * the first use.
*/ */
void avGenRand(char *buf, u32_t bufLen); void random_bytes(unsigned char *buf, u32_t len);
#endif /* MD5_SUPPORT */
/* #endif /* PPP_SUPPORT */
* Return a new random number. #endif /* MAGIC_H */
*/
u32_t avRandom(void);
#endif /* RANDM_H */
void magic_init __P((void)); /* Initialize the magic number generator */
u_int32_t magic __P((void)); /* Returns the next magic number */
/* Fill buffer with random bytes */
void random_bytes __P((unsigned char *buf, int len));