[openssl.git] / crypto / rand / md_rand.c

/* 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 16  /* require 128 bits = 16 bytes 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>

#ifdef BN_DEBUG
# define PREDICT
#endif

/* #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 double entropy=0;
static int initialized=0;

#ifdef PREDICT
int rand_predictable=0;
#endif

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, double add_entropy);
static int ssleay_rand_bytes(unsigned char *buf, int num);
static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);
static int ssleay_rand_status(void);

RAND_METHOD rand_ssleay_meth={
        ssleay_rand_seed,
        ssleay_rand_bytes,
        ssleay_rand_cleanup,
        ssleay_rand_add,
        ssleay_rand_pseudo_bytes,
        ssleay_rand_status
        }; 

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, double 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];
                }
        if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
            entropy += add;
        CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
        
#ifndef THREADS 
        assert(md_c[1] == md_count[1]);
#endif
        }

static void ssleay_rand_seed(const void *buf, int num)
        {
        ssleay_rand_add(buf, num, num);
        }

static void ssleay_rand_initialize(void)
        {
        unsigned long l;
#ifndef GETPID_IS_MEANINGLESS
        pid_t curr_pid = getpid();
#endif
#ifdef DEVRANDOM
        FILE *fh;
#endif

#ifdef NORAND
        return;
#endif

        CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
        /* put in some default random data, we need more than just this */
#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, FreeBSD and OpenBSD
         * have this. Use /dev/urandom if you can as /dev/random may block
         * if it runs out of random entries.  */

        if ((fh = fopen(DEVRANDOM, "r")) != NULL)
                {
                unsigned char tmpbuf[ENTROPY_NEEDED];
                int n;
                
                setvbuf(fh, NULL, _IONBF, 0);
                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);
        initialized=1;
        }

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;
#ifndef GETPID_IS_MEANINGLESS
        pid_t curr_pid = getpid();
#endif

#ifdef PREDICT
        if (rand_predictable)
                {
                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 (!initialized)
                ssleay_rand_initialize();

        ok = (entropy >= ENTROPY_NEEDED);
        if (!ok)
                {
                /* If the PRNG state is not yet unpredictable, then seeing
                 * the PRNG output may help attackers to determine the new
                 * state; thus we have to decrease the entropy estimate.
                 * Once we've had enough initial seeding we don't bother to
                 * adjust the entropy count, though, because we're not ambitious
                 * to provide *information-theoretic* randomness.
                 */
                entropy -= num;
                if (entropy < 0)
                        entropy = 0;
                }

        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);
        }

static int ssleay_rand_status(void)
        {
        if (!initialized)
                ssleay_rand_initialize();
        return (entropy >= ENTROPY_NEEDED);
        }

#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 original 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 approximately 49,000 56 byte MD5
 * digests or digesting 2.7 mbytes.  What I have put in place would
 * be 48 16k MD5 digests, or effectively 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