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/*
* magic.c - PPP Magic Number routines.
*
* Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The name "Carnegie Mellon University" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For permission or any legal
* details, please contact
* Office of Technology Transfer
* Carnegie Mellon University
* 5000 Forbes Avenue
* Pittsburgh, PA 15213-3890
* (412) 268-4387, fax: (412) 268-7395
* tech-transfer@andrew.cmu.edu
*
* 4. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Computing Services
* at Carnegie Mellon University (http://www.cmu.edu/computing/)."
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*****************************************************************************
* randm.c - Random number generator program file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* Copyright (c) 1998 by Global Election Systems Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <marc@mbsi.ca>
* Ported to lwIP.
* 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
* Extracted from avos.
*****************************************************************************/
#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
#include "netif/ppp/ppp_impl.h"
#include "netif/ppp/magic.h"
#if PPP_MD5_RANDM /* Using MD5 for better randomness if enabled */
#include "netif/ppp/pppcrypt.h"
#define MD5_HASH_SIZE 16
static char magic_randpool[MD5_HASH_SIZE]; /* Pool of randomness. */
static long magic_randcount; /* Pseudo-random incrementer */
static u32_t magic_randomseed; /* Seed used for random number generation. */
/*
* 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.
*
* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
*/
static void magic_churnrand(char *rand_data, u32_t rand_len) {
lwip_md5_context md5_ctx;
/* LWIP_DEBUGF(LOG_INFO, ("magic_churnrand: %u@%P\n", rand_len, rand_data)); */
lwip_md5_init(&md5_ctx);
lwip_md5_starts(&md5_ctx);
lwip_md5_update(&md5_ctx, (u_char *)magic_randpool, sizeof(magic_randpool));
if (rand_data) {
lwip_md5_update(&md5_ctx, (u_char *)rand_data, rand_len);
} else {
struct {
/* INCLUDE fields for any system sources of randomness */
u32_t jiffies;
#ifdef LWIP_RAND
u32_t rand;
#endif /* LWIP_RAND */
} sys_data;
magic_randomseed += sys_jiffies();
sys_data.jiffies = magic_randomseed;
#ifdef LWIP_RAND
sys_data.rand = LWIP_RAND();
#endif /* LWIP_RAND */
/* Load sys_data fields here. */
lwip_md5_update(&md5_ctx, (u_char *)&sys_data, sizeof(sys_data));
}
lwip_md5_finish(&md5_ctx, (u_char *)magic_randpool);
lwip_md5_free(&md5_ctx);
/* LWIP_DEBUGF(LOG_INFO, ("magic_churnrand: -> 0\n")); */
}
/*
* Initialize the random number generator.
*/
void magic_init(void) {
magic_churnrand(NULL, 0);
}
/*
* Randomize our random seed value.
*/
void magic_randomize(void) {
magic_churnrand(NULL, 0);
}
/*
* magic_random_bytes - Fill a buffer with random bytes.
*
* Use the random pool to generate random data. This degrades to pseudo
* random when used faster than randomness is supplied using magic_churnrand().
* 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
* narrow enough to make a search feasible.
*
* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
*
* XXX Why does he not just call magic_churnrand() for each block? Probably
* so that you don't ever publish the seed which could possibly help
* predict future values.
* XXX Why don't we preserve md5 between blocks and just update it with
* magic_randcount each time? Probably there is a weakness but I wish that
* it was documented.
*/
void magic_random_bytes(unsigned char *buf, u32_t buf_len) {
lwip_md5_context md5_ctx;
u_char tmp[MD5_HASH_SIZE];
u32_t n;
while (buf_len > 0) {
lwip_md5_init(&md5_ctx);
lwip_md5_starts(&md5_ctx);
lwip_md5_update(&md5_ctx, (u_char *)magic_randpool, sizeof(magic_randpool));
lwip_md5_update(&md5_ctx, (u_char *)&magic_randcount, sizeof(magic_randcount));
lwip_md5_finish(&md5_ctx, tmp);
lwip_md5_free(&md5_ctx);
magic_randcount++;
n = LWIP_MIN(buf_len, MD5_HASH_SIZE);
MEMCPY(buf, tmp, n);
buf += n;
buf_len -= n;
}
}
/*
* Return a new random number.
*/
u32_t magic(void) {
u32_t new_rand;
magic_random_bytes((unsigned char *)&new_rand, sizeof(new_rand));
return new_rand;
}
#else /* PPP_MD5_RANDM */
/*****************************/
/*** LOCAL DATA STRUCTURES ***/
/*****************************/
#ifndef LWIP_RAND
static int magic_randomized; /* Set when truely randomized. */
#endif /* LWIP_RAND */
static u32_t magic_randomseed; /* Seed used for random number generation. */
/***********************************/
/*** PUBLIC FUNCTION DEFINITIONS ***/
/***********************************/
/*
* Initialize the random number generator.
*
* Here we attempt to compute a random number seed but even if
* it isn't random, we'll randomize it later.
*
* The current method uses the fields from the real time clock,
* the idle process counter, the millisecond counter, and the
* hardware timer tick counter. When this is invoked
* in startup(), then the idle counter and timer values may
* repeat after each boot and the real time clock may not be
* operational. Thus we call it again on the first random
* event.
*/
void magic_init(void) {
magic_randomseed += sys_jiffies();
#ifndef LWIP_RAND
/* Initialize the Borland random number generator. */
srand((unsigned)magic_randomseed);
#endif /* LWIP_RAND */
}
/*
* magic_init - Initialize the magic number generator.
*
* Randomize our random seed value. Here we use the fact that
* this function is called at *truely random* times by the polling
* and network functions. Here we only get 16 bits of new random
* value but we use the previous value to randomize the other 16
* bits.
*/
void magic_randomize(void) {
#ifndef LWIP_RAND
if (!magic_randomized) {
magic_randomized = !0;
magic_init();
/* The initialization function also updates the seed. */
} else {
#endif /* LWIP_RAND */
magic_randomseed += sys_jiffies();
#ifndef LWIP_RAND
}
#endif /* LWIP_RAND */
}
/*
* Return a new random number.
*
* Here we use the Borland rand() function to supply a pseudo random
* number which we make truely random by combining it with our own
* seed which is randomized by truely random events.
* Thus the numbers will be truely random unless there have been no
* operator or network events in which case it will be pseudo random
* seeded by the real time clock.
*/
u32_t magic(void) {
#ifdef LWIP_RAND
return LWIP_RAND() + magic_randomseed;
#else /* LWIP_RAND */
return ((u32_t)rand() << 16) + (u32_t)rand() + magic_randomseed;
#endif /* LWIP_RAND */
}
/*
* magic_random_bytes - Fill a buffer with random bytes.
*/
void magic_random_bytes(unsigned char *buf, u32_t buf_len) {
u32_t new_rand, n;
while (buf_len > 0) {
new_rand = magic();
n = LWIP_MIN(buf_len, sizeof(new_rand));
MEMCPY(buf, &new_rand, n);
buf += n;
buf_len -= n;
}
}
#endif /* PPP_MD5_RANDM */
/*
* Return a new random number between 0 and (2^pow)-1 included.
*/
u32_t magic_pow(u8_t pow) {
return magic() & ~(~0UL<<pow);
}
#endif /* PPP_SUPPORT */