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openssl/crypto/rand/md_rand.c
Bodo Möller c88a900fa1 update PRNG documentation/comments
2000-01-22 23:11:13 +00:00

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/* crypto/rand/md_rand.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* 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 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 AUTHOR OR 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.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
#define ENTROPY_NEEDED 32 /* require 128 bits of randomness */
#ifndef MD_RAND_DEBUG
# ifndef NDEBUG
# define NDEBUG
# endif
#endif
#include <assert.h>
#include <stdio.h>
#include <time.h>
#include <string.h>
#include "openssl/e_os.h"
#include <openssl/crypto.h>
#include <openssl/err.h>
#if !defined(USE_MD5_RAND) && !defined(USE_SHA1_RAND) && !defined(USE_MDC2_RAND) && !defined(USE_MD2_RAND)
#if !defined(NO_SHA) && !defined(NO_SHA1)
#define USE_SHA1_RAND
#elif !defined(NO_MD5)
#define USE_MD5_RAND
#elif !defined(NO_MDC2) && !defined(NO_DES)
#define USE_MDC2_RAND
#elif !defined(NO_MD2)
#define USE_MD2_RAND
#else
#error No message digest algorithm available
#endif
#endif
/* Changed how the state buffer used. I now attempt to 'wrap' such
* that I don't run over the same locations the next time go through
* the 1023 bytes - many thanks to
* Robert J. LeBlanc <rjl@renaissoft.com> for his comments
*/
#if defined(USE_MD5_RAND)
#include <openssl/md5.h>
#define MD_DIGEST_LENGTH MD5_DIGEST_LENGTH
#define MD_CTX MD5_CTX
#define MD_Init(a) MD5_Init(a)
#define MD_Update(a,b,c) MD5_Update(a,b,c)
#define MD_Final(a,b) MD5_Final(a,b)
#define MD(a,b,c) MD5(a,b,c)
#elif defined(USE_SHA1_RAND)
#include <openssl/sha.h>
#define MD_DIGEST_LENGTH SHA_DIGEST_LENGTH
#define MD_CTX SHA_CTX
#define MD_Init(a) SHA1_Init(a)
#define MD_Update(a,b,c) SHA1_Update(a,b,c)
#define MD_Final(a,b) SHA1_Final(a,b)
#define MD(a,b,c) SHA1(a,b,c)
#elif defined(USE_MDC2_RAND)
#include <openssl/mdc2.h>
#define MD_DIGEST_LENGTH MDC2_DIGEST_LENGTH
#define MD_CTX MDC2_CTX
#define MD_Init(a) MDC2_Init(a)
#define MD_Update(a,b,c) MDC2_Update(a,b,c)
#define MD_Final(a,b) MDC2_Final(a,b)
#define MD(a,b,c) MDC2(a,b,c)
#elif defined(USE_MD2_RAND)
#include <openssl/md2.h>
#define MD_DIGEST_LENGTH MD2_DIGEST_LENGTH
#define MD_CTX MD2_CTX
#define MD_Init(a) MD2_Init(a)
#define MD_Update(a,b,c) MD2_Update(a,b,c)
#define MD_Final(a,b) MD2_Final(a,b)
#define MD(a,b,c) MD2(a,b,c)
#endif
#include <openssl/rand.h>
/* #define NORAND 1 */
/* #define PREDICT 1 */
#define STATE_SIZE 1023
static int state_num=0,state_index=0;
static unsigned char state[STATE_SIZE+MD_DIGEST_LENGTH];
static unsigned char md[MD_DIGEST_LENGTH];
static long md_count[2]={0,0};
static unsigned entropy=0;
const char *RAND_version="RAND" OPENSSL_VERSION_PTEXT;
static void ssleay_rand_cleanup(void);
static void ssleay_rand_seed(const void *buf, int num);
static void ssleay_rand_add(const void *buf, int num, int add_entropy);
static int ssleay_rand_bytes(unsigned char *buf, int num);
static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);
RAND_METHOD rand_ssleay_meth={
ssleay_rand_seed,
ssleay_rand_bytes,
ssleay_rand_cleanup,
ssleay_rand_add,
ssleay_rand_pseudo_bytes,
};
RAND_METHOD *RAND_SSLeay(void)
{
return(&rand_ssleay_meth);
}
static void ssleay_rand_cleanup(void)
{
memset(state,0,sizeof(state));
state_num=0;
state_index=0;
memset(md,0,MD_DIGEST_LENGTH);
md_count[0]=0;
md_count[1]=0;
entropy=0;
}
static void ssleay_rand_add(const void *buf, int num, int add)
{
int i,j,k,st_idx;
long md_c[2];
unsigned char local_md[MD_DIGEST_LENGTH];
MD_CTX m;
#ifdef NORAND
return;
#endif
/*
* (Based on the rand(3) manpage)
*
* The input is chopped up into units of 20 bytes (or less for
* the last block). Each of these blocks is run through the hash
* function as follows: The data passed to the hash function
* is the current 'md', the same number of bytes from the 'state'
* (the location determined by in incremented looping index) as
* the current 'block', the new key data 'block', and 'count'
* (which is incremented after each use).
* The result of this is kept in 'md' and also xored into the
* 'state' at the same locations that were used as input into the
* hash function.
*/
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
st_idx=state_index;
/* use our own copies of the counters so that even
* if a concurrent thread seeds with exactly the
* same data and uses the same subarray there's _some_
* difference */
md_c[0] = md_count[0];
md_c[1] = md_count[1];
memcpy(local_md, md, sizeof md);
/* state_index <= state_num <= STATE_SIZE */
state_index += num;
if (state_index >= STATE_SIZE)
{
state_index%=STATE_SIZE;
state_num=STATE_SIZE;
}
else if (state_num < STATE_SIZE)
{
if (state_index > state_num)
state_num=state_index;
}
/* state_index <= state_num <= STATE_SIZE */
/* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
* are what we will use now, but other threads may use them
* as well */
md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
for (i=0; i<num; i+=MD_DIGEST_LENGTH)
{
j=(num-i);
j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
MD_Init(&m);
MD_Update(&m,local_md,MD_DIGEST_LENGTH);
k=(st_idx+j)-STATE_SIZE;
if (k > 0)
{
MD_Update(&m,&(state[st_idx]),j-k);
MD_Update(&m,&(state[0]),k);
}
else
MD_Update(&m,&(state[st_idx]),j);
MD_Update(&m,buf,j);
MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
MD_Final(local_md,&m);
md_c[1]++;
buf=(const char *)buf + j;
for (k=0; k<j; k++)
{
/* Parallel threads may interfere with this,
* but always each byte of the new state is
* the XOR of some previous value of its
* and local_md (itermediate values may be lost).
* Alway using locking could hurt performance more
* than necessary given that conflicts occur only
* when the total seeding is longer than the random
* state. */
state[st_idx++]^=local_md[k];
if (st_idx >= STATE_SIZE)
st_idx=0;
}
}
memset((char *)&m,0,sizeof(m));
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
/* Don't just copy back local_md into md -- this could mean that
* other thread's seeding remains without effect (except for
* the incremented counter). By XORing it we keep at least as
* much entropy as fits into md. */
for (k = 0; k < sizeof md; k++)
{
md[k] ^= local_md[k];
}
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
#ifndef THREADS
assert(md_c[1] == md_count[1]);
#endif
if (entropy < ENTROPY_NEEDED)
entropy += add;
}
static void ssleay_rand_seed(const void *buf, int num)
{
ssleay_rand_add(buf, num, num);
}
static int ssleay_rand_bytes(unsigned char *buf, int num)
{
int i,j,k,st_num,st_idx;
int ok;
long md_c[2];
unsigned char local_md[MD_DIGEST_LENGTH];
MD_CTX m;
static int init=1;
unsigned long l;
#ifndef GETPID_IS_MEANINGLESS
pid_t curr_pid = getpid();
#endif
#ifdef DEVRANDOM
FILE *fh;
#endif
#ifdef PREDICT
{
static unsigned char val=0;
for (i=0; i<num; i++)
buf[i]=val++;
return(1);
}
#endif
/*
* (Based on the rand(3) manpage:)
*
* For each group of 10 bytes (or less), we do the following:
*
* Input into the hash function the top 10 bytes from the
* local 'md' (which is initialized from the global 'md'
* before any bytes are generated), the bytes that are
* to be overwritten by the random bytes, and bytes from the
* 'state' (incrementing looping index). From this digest output
* (which is kept in 'md'), the top (up to) 10 bytes are
* returned to the caller and the bottom (up to) 10 bytes are xored
* into the 'state'.
* Finally, after we have finished 'num' random bytes for the
* caller, 'count' (which is incremented) and the local and global 'md'
* are fed into the hash function and the results are kept in the
* global 'md'.
*/
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
if (init)
{
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
/* put in some default random data, we need more than
* just this */
RAND_add(&m,sizeof(m),0);
#ifndef GETPID_IS_MEANINGLESS
l=curr_pid;
RAND_add(&l,sizeof(l),0);
l=getuid();
RAND_add(&l,sizeof(l),0);
#endif
l=time(NULL);
RAND_add(&l,sizeof(l),0);
#ifdef DEVRANDOM
/*
* Use a random entropy pool device.
* Linux 1.3.x and FreeBSD-Current has
* this. Use /dev/urandom if you can
* as /dev/random will block if it runs out
* of random entries.
*/
if ((fh = fopen(DEVRANDOM, "r")) != NULL)
{
unsigned char tmpbuf[ENTROPY_NEEDED];
int n;
n=fread((unsigned char *)tmpbuf,1,ENTROPY_NEEDED,fh);
fclose(fh);
RAND_add(tmpbuf,sizeof tmpbuf,n);
memset(tmpbuf,0,n);
}
#endif
#ifdef PURIFY
memset(state,0,STATE_SIZE);
memset(md,0,MD_DIGEST_LENGTH);
#endif
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
init=0;
}
ok = (entropy >= ENTROPY_NEEDED);
st_idx=state_index;
st_num=state_num;
md_c[0] = md_count[0];
md_c[1] = md_count[1];
memcpy(local_md, md, sizeof md);
state_index+=num;
if (state_index > state_num)
state_index %= state_num;
/* state[st_idx], ..., state[(st_idx + num - 1) % st_num]
* are now ours (but other threads may use them too) */
md_count[0] += 1;
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
while (num > 0)
{
j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
num-=j;
MD_Init(&m);
#ifndef GETPID_IS_MEANINGLESS
if (curr_pid) /* just in the first iteration to save time */
{
MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid);
curr_pid = 0;
}
#endif
MD_Update(&m,&(local_md[MD_DIGEST_LENGTH/2]),MD_DIGEST_LENGTH/2);
MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
#ifndef PURIFY
MD_Update(&m,buf,j); /* purify complains */
#endif
k=(st_idx+j)-st_num;
if (k > 0)
{
MD_Update(&m,&(state[st_idx]),j-k);
MD_Update(&m,&(state[0]),k);
}
else
MD_Update(&m,&(state[st_idx]),j);
MD_Final(local_md,&m);
for (i=0; i<j; i++)
{
state[st_idx++]^=local_md[i]; /* may compete with other threads */
*(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
if (st_idx >= st_num)
st_idx=0;
}
}
MD_Init(&m);
MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
MD_Update(&m,local_md,MD_DIGEST_LENGTH);
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
MD_Update(&m,md,MD_DIGEST_LENGTH);
MD_Final(md,&m);
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
memset(&m,0,sizeof(m));
if (ok)
return(1);
else
{
RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
return(0);
}
}
/* pseudo-random bytes that are guaranteed to be unique but not
unpredictable */
static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
{
int ret, err;
ret = RAND_bytes(buf, num);
if (ret == 0)
{
err = ERR_peek_error();
if (ERR_GET_LIB(err) == ERR_LIB_RAND &&
ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)
(void)ERR_get_error();
}
return (ret);
}
#ifdef WINDOWS
#include <windows.h>
#include <openssl/rand.h>
/*****************************************************************************
* Initialisation function for the SSL random generator. Takes the contents
* of the screen as random seed.
*
* Created 960901 by Gertjan van Oosten, gertjan@West.NL, West Consulting B.V.
*
* Code adapted from
* <URL:http://www.microsoft.com/kb/developr/win_dk/q97193.htm>;
* the original copyright message is:
*
* (C) Copyright Microsoft Corp. 1993. All rights reserved.
*
* You have a royalty-free right to use, modify, reproduce and
* distribute the Sample Files (and/or any modified version) in
* any way you find useful, provided that you agree that
* Microsoft has no warranty obligations or liability for any
* Sample Application Files which are modified.
*/
/*
* I have modified the loading of bytes via RAND_seed() mechanism since
* the origional would have been very very CPU intensive since RAND_seed()
* does an MD5 per 16 bytes of input. The cost to digest 16 bytes is the same
* as that to digest 56 bytes. So under the old system, a screen of
* 1024*768*256 would have been CPU cost of approximatly 49,000 56 byte MD5
* digests or digesting 2.7 mbytes. What I have put in place would
* be 48 16k MD5 digests, or efectivly 48*16+48 MD5 bytes or 816 kbytes
* or about 3.5 times as much.
* - eric
*/
void RAND_screen(void)
{
HDC hScrDC; /* screen DC */
HDC hMemDC; /* memory DC */
HBITMAP hBitmap; /* handle for our bitmap */
HBITMAP hOldBitmap; /* handle for previous bitmap */
BITMAP bm; /* bitmap properties */
unsigned int size; /* size of bitmap */
char *bmbits; /* contents of bitmap */
int w; /* screen width */
int h; /* screen height */
int y; /* y-coordinate of screen lines to grab */
int n = 16; /* number of screen lines to grab at a time */
/* Create a screen DC and a memory DC compatible to screen DC */
hScrDC = CreateDC("DISPLAY", NULL, NULL, NULL);
hMemDC = CreateCompatibleDC(hScrDC);
/* Get screen resolution */
w = GetDeviceCaps(hScrDC, HORZRES);
h = GetDeviceCaps(hScrDC, VERTRES);
/* Create a bitmap compatible with the screen DC */
hBitmap = CreateCompatibleBitmap(hScrDC, w, n);
/* Select new bitmap into memory DC */
hOldBitmap = SelectObject(hMemDC, hBitmap);
/* Get bitmap properties */
GetObject(hBitmap, sizeof(BITMAP), (LPSTR)&bm);
size = (unsigned int)bm.bmWidthBytes * bm.bmHeight * bm.bmPlanes;
bmbits = Malloc(size);
if (bmbits) {
/* Now go through the whole screen, repeatedly grabbing n lines */
for (y = 0; y < h-n; y += n)
{
unsigned char md[MD_DIGEST_LENGTH];
/* Bitblt screen DC to memory DC */
BitBlt(hMemDC, 0, 0, w, n, hScrDC, 0, y, SRCCOPY);
/* Copy bitmap bits from memory DC to bmbits */
GetBitmapBits(hBitmap, size, bmbits);
/* Get the MD5 of the bitmap */
MD(bmbits,size,md);
/* Seed the random generator with the MD5 digest */
RAND_seed(md, MD_DIGEST_LENGTH);
}
Free(bmbits);
}
/* Select old bitmap back into memory DC */
hBitmap = SelectObject(hMemDC, hOldBitmap);
/* Clean up */
DeleteObject(hBitmap);
DeleteDC(hMemDC);
DeleteDC(hScrDC);
}
#endif
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