src/third_party/openssl/openssl/crypto/rand/md_rand.c - cobalt - Git at Google

 /* 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.]
  */
 /* ====================================================================
  * Copyright (c) 1998-2001 The OpenSSL Project.  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. All advertising materials mentioning features or use of this
  *    software must display the following acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  *
  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  *    endorse or promote products derived from this software without
  *    prior written permission. For written permission, please contact
  *    openssl-core@openssl.org.
  *
  * 5. Products derived from this software may not be called "OpenSSL"
  *    nor may "OpenSSL" appear in their names without prior written
  *    permission of the OpenSSL Project.
  *
  * 6. Redistributions of any form whatsoever must retain the following
  *    acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  *
  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  * EXPRESSED 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 OpenSSL PROJECT OR
  * ITS 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.
  * ====================================================================
  *
  * This product includes cryptographic software written by Eric Young
  * (eay@cryptsoft.com).  This product includes software written by Tim
  * Hudson (tjh@cryptsoft.com).
  *
  */

 #define OPENSSL_FIPSEVP

 #ifdef MD_RAND_DEBUG
 # ifndef NDEBUG
 #  define NDEBUG
 # endif
 #endif

 #include <openssl/opensslconf.h>
 #if !defined(OPENSSL_SYS_STARBOARD)
 #include <assert.h>
 #include <stdio.h>
 #include <string.h>
 #endif  // !defined(OPENSSL_SYS_STARBOARD)

 #include "e_os.h"

 #include <openssl/crypto.h>
 #include <openssl/rand.h>
 #include "rand_lcl.h"

 #include <openssl/err.h>

 #ifdef BN_DEBUG
 # define PREDICT
 #endif

 /* #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;

 static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
                                            * holds CRYPTO_LOCK_RAND (to
                                            * prevent double locking) */
 /* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
 /* valid iff crypto_lock_rand is set */
 static CRYPTO_THREADID locking_threadid;

 #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_nopseudo_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_nopseudo_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)
 {
     OPENSSL_cleanse(state, sizeof(state));
     state_num = 0;
     state_index = 0;
     OPENSSL_cleanse(md, MD_DIGEST_LENGTH);
     md_count[0] = 0;
     md_count[1] = 0;
     entropy = 0;
     initialized = 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];
     EVP_MD_CTX m;
     int do_not_lock;

     if (!num)
         return;

     /*
      * (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.
      */

     /* check if we already have the lock */
     if (crypto_lock_rand) {
         CRYPTO_THREADID cur;
         CRYPTO_THREADID_current(&cur);
         CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
         do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
         CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
     } else
         do_not_lock = 0;

     if (!do_not_lock)
         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];

     OPENSSL_port_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);

     if (!do_not_lock)
         CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

     EVP_MD_CTX_init(&m);
     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);

         /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
         MD_Update(&m, buf, j);
         /*
          * We know that line may cause programs such as purify and valgrind
          * to complain about use of uninitialized data.  The problem is not,
          * it's with the caller.  Removing that line will make sure you get
          * really bad randomness and thereby other problems such as very
          * insecure keys.
          */

         MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));
         MD_Final(&m, local_md);
         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;
         }
     }
     EVP_MD_CTX_cleanup(&m);

     if (!do_not_lock)
         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 < (int)sizeof(md); k++) {
         md[k] ^= local_md[k];
     }
     if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
         entropy += add;
     if (!do_not_lock)
         CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
     OPENSSL_port_assert(md_c[1] == md_count[1]);
 #endif
 }

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

 int ssleay_rand_bytes(unsigned char *buf, int num, int pseudo, int lock)
 {
     static volatile int stirred_pool = 0;
     int i, j, k, st_num, st_idx;
     int num_ceil;
     int ok;
     long md_c[2];
     unsigned char local_md[MD_DIGEST_LENGTH];
     EVP_MD_CTX m;
 #ifndef GETPID_IS_MEANINGLESS
     pid_t curr_pid = getpid();
 #endif
     int do_stir_pool = 0;

 #ifdef PREDICT
     if (rand_predictable) {
         static unsigned char val = 0;

         for (i = 0; i < num; i++)
             buf[i] = val++;
         return (1);
     }
 #endif

     if (num <= 0)
         return 1;

     EVP_MD_CTX_init(&m);
     /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
     num_ceil =
         (1 + (num - 1) / (MD_DIGEST_LENGTH / 2)) * (MD_DIGEST_LENGTH / 2);

     /*
      * (Based on the rand(3) manpage:)
      *
      * For each group of 10 bytes (or less), we do the following:
      *
      * Input into the hash function 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 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'.
      */
     if (lock)
         CRYPTO_w_lock(CRYPTO_LOCK_RAND);

     /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
     CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
     CRYPTO_THREADID_current(&locking_threadid);
     CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
     crypto_lock_rand = 1;

     if (!initialized) {
         RAND_poll();
         initialized = 1;
     }

     if (!stirred_pool)
         do_stir_pool = 1;

     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. NOTE: This approach fails if the program forks before
          * we have enough entropy. Entropy should be collected in a separate
          * input pool and be transferred to the output pool only when the
          * entropy limit has been reached.
          */
         entropy -= num;
         if (entropy < 0)
             entropy = 0;
     }

     if (do_stir_pool) {
         /*
          * In the output function only half of 'md' remains secret, so we
          * better make sure that the required entropy gets 'evenly
          * distributed' through 'state', our randomness pool. The input
          * function (ssleay_rand_add) chains all of 'md', which makes it more
          * suitable for this purpose.
          */

         int n = STATE_SIZE;     /* so that the complete pool gets accessed */
         while (n > 0) {
 #if MD_DIGEST_LENGTH > 20
 # error "Please adjust DUMMY_SEED."
 #endif
 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
             /*
              * Note that the seed does not matter, it's just that
              * ssleay_rand_add expects to have something to hash.
              */
             ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
             n -= MD_DIGEST_LENGTH;
         }
         if (ok)
             stirred_pool = 1;
     }

     st_idx = state_index;
     st_num = state_num;
     md_c[0] = md_count[0];
     md_c[1] = md_count[1];
     OPENSSL_port_memcpy(local_md, md, sizeof md);

     state_index += num_ceil;
     if (state_index > state_num)
         state_index %= state_num;

     /*
      * state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num] are now
      * ours (but other threads may use them too)
      */

     md_count[0] += 1;

     /* before unlocking, we must clear 'crypto_lock_rand' */
     crypto_lock_rand = 0;
     if (lock)
         CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

     while (num > 0) {
         /* num_ceil -= MD_DIGEST_LENGTH/2 */
         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);
         MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));

 #ifndef PURIFY                  /* purify complains */
         /*
          * The following line uses the supplied buffer as a small source of
          * entropy: since this buffer is often uninitialised it may cause
          * programs such as purify or valgrind to complain. So for those
          * builds it is not used: the removal of such a small source of
          * entropy has negligible impact on security.
          */
         MD_Update(&m, buf, j);
 #endif

         k = (st_idx + MD_DIGEST_LENGTH / 2) - st_num;
         if (k > 0) {
             MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2 - k);
             MD_Update(&m, &(state[0]), k);
         } else
             MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2);
         MD_Final(&m, local_md);

         for (i = 0; i < MD_DIGEST_LENGTH / 2; i++) {
             /* may compete with other threads */
             state[st_idx++] ^= local_md[i];
             if (st_idx >= st_num)
                 st_idx = 0;
             if (i < j)
                 *(buf++) = local_md[i + MD_DIGEST_LENGTH / 2];
         }
     }

     MD_Init(&m);
     MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));
     MD_Update(&m, local_md, MD_DIGEST_LENGTH);
     if (lock)
         CRYPTO_w_lock(CRYPTO_LOCK_RAND);
     MD_Update(&m, md, MD_DIGEST_LENGTH);
     MD_Final(&m, md);
     if (lock)
         CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

     EVP_MD_CTX_cleanup(&m);
     if (ok)
         return (1);
     else if (pseudo)
         return 0;
     else {
         RANDerr(RAND_F_SSLEAY_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED);
         ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
                            "http://www.openssl.org/support/faq.html");
         return (0);
     }
 }

 static int ssleay_rand_nopseudo_bytes(unsigned char *buf, int num)
 {
     return ssleay_rand_bytes(buf, num, 0, 1);
 }

 /*
  * pseudo-random bytes that are guaranteed to be unique but not unpredictable
  */
 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
 {
     return ssleay_rand_bytes(buf, num, 1, 1);
 }

 static int ssleay_rand_status(void)
 {
     CRYPTO_THREADID cur;
     int ret;
     int do_not_lock;

     CRYPTO_THREADID_current(&cur);
     /*
      * check if we already have the lock (could happen if a RAND_poll()
      * implementation calls RAND_status())
      */
     if (crypto_lock_rand) {
         CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
         do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
         CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
     } else
         do_not_lock = 0;

     if (!do_not_lock) {
         CRYPTO_w_lock(CRYPTO_LOCK_RAND);

         /*
          * prevent ssleay_rand_bytes() from trying to obtain the lock again
          */
         CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
         CRYPTO_THREADID_cpy(&locking_threadid, &cur);
         CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
         crypto_lock_rand = 1;
     }

     if (!initialized) {
         RAND_poll();
         initialized = 1;
     }

     ret = entropy >= ENTROPY_NEEDED;

     if (!do_not_lock) {
         /* before unlocking, we must clear 'crypto_lock_rand' */
         crypto_lock_rand = 0;

         CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
     }

     return ret;
 }
	/* 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.]
	*/
	/* ====================================================================
	* Copyright (c) 1998-2001 The OpenSSL Project. 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. All advertising materials mentioning features or use of this
	* software must display the following acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
	*
	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	* endorse or promote products derived from this software without
	* prior written permission. For written permission, please contact
	* openssl-core@openssl.org.
	*
	* 5. Products derived from this software may not be called "OpenSSL"
	* nor may "OpenSSL" appear in their names without prior written
	* permission of the OpenSSL Project.
	*
	* 6. Redistributions of any form whatsoever must retain the following
	* acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
	*
	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	* EXPRESSED 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 OpenSSL PROJECT OR
	* ITS 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.
	* ====================================================================
	*
	* This product includes cryptographic software written by Eric Young
	* (eay@cryptsoft.com). This product includes software written by Tim
	* Hudson (tjh@cryptsoft.com).
	*
	*/

	#define OPENSSL_FIPSEVP

	#ifdef MD_RAND_DEBUG
	# ifndef NDEBUG
	# define NDEBUG
	# endif
	#endif

	#include <openssl/opensslconf.h>
	#if !defined(OPENSSL_SYS_STARBOARD)
	#include <assert.h>
	#include <stdio.h>
	#include <string.h>
	#endif // !defined(OPENSSL_SYS_STARBOARD)

	#include "e_os.h"

	#include <openssl/crypto.h>
	#include <openssl/rand.h>
	#include "rand_lcl.h"

	#include <openssl/err.h>

	#ifdef BN_DEBUG
	# define PREDICT
	#endif

	/* #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;

	static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
	* holds CRYPTO_LOCK_RAND (to
	* prevent double locking) */
	/* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
	/* valid iff crypto_lock_rand is set */
	static CRYPTO_THREADID locking_threadid;

	#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_nopseudo_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_nopseudo_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)
	{
	OPENSSL_cleanse(state, sizeof(state));
	state_num = 0;
	state_index = 0;
	OPENSSL_cleanse(md, MD_DIGEST_LENGTH);
	md_count[0] = 0;
	md_count[1] = 0;
	entropy = 0;
	initialized = 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];
	EVP_MD_CTX m;
	int do_not_lock;

	if (!num)
	return;

	/*
	* (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.
	*/

	/* check if we already have the lock */
	if (crypto_lock_rand) {
	CRYPTO_THREADID cur;
	CRYPTO_THREADID_current(&cur);
	CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
	do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
	CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
	} else
	do_not_lock = 0;

	if (!do_not_lock)
	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];

	OPENSSL_port_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);

	if (!do_not_lock)
	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	EVP_MD_CTX_init(&m);
	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);

	/* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
	MD_Update(&m, buf, j);
	/*
	* We know that line may cause programs such as purify and valgrind
	* to complain about use of uninitialized data. The problem is not,
	* it's with the caller. Removing that line will make sure you get
	* really bad randomness and thereby other problems such as very
	* insecure keys.
	*/

	MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));
	MD_Final(&m, local_md);
	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;
	}
	}
	EVP_MD_CTX_cleanup(&m);

	if (!do_not_lock)
	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 < (int)sizeof(md); k++) {
	md[k] ^= local_md[k];
	}
	if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
	entropy += add;
	if (!do_not_lock)
	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	#if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
	OPENSSL_port_assert(md_c[1] == md_count[1]);
	#endif
	}

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

	int ssleay_rand_bytes(unsigned char *buf, int num, int pseudo, int lock)
	{
	static volatile int stirred_pool = 0;
	int i, j, k, st_num, st_idx;
	int num_ceil;
	int ok;
	long md_c[2];
	unsigned char local_md[MD_DIGEST_LENGTH];
	EVP_MD_CTX m;
	#ifndef GETPID_IS_MEANINGLESS
	pid_t curr_pid = getpid();
	#endif
	int do_stir_pool = 0;

	#ifdef PREDICT
	if (rand_predictable) {
	static unsigned char val = 0;

	for (i = 0; i < num; i++)
	buf[i] = val++;
	return (1);
	}
	#endif

	if (num <= 0)
	return 1;

	EVP_MD_CTX_init(&m);
	/* round upwards to multiple of MD_DIGEST_LENGTH/2 */
	num_ceil =
	(1 + (num - 1) / (MD_DIGEST_LENGTH / 2)) * (MD_DIGEST_LENGTH / 2);

	/*
	* (Based on the rand(3) manpage:)
	*
	* For each group of 10 bytes (or less), we do the following:
	*
	* Input into the hash function 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 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'.
	*/
	if (lock)
	CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	/* prevent ssleay_rand_bytes() from trying to obtain the lock again */
	CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
	CRYPTO_THREADID_current(&locking_threadid);
	CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
	crypto_lock_rand = 1;

	if (!initialized) {
	RAND_poll();
	initialized = 1;
	}

	if (!stirred_pool)
	do_stir_pool = 1;

	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. NOTE: This approach fails if the program forks before
	* we have enough entropy. Entropy should be collected in a separate
	* input pool and be transferred to the output pool only when the
	* entropy limit has been reached.
	*/
	entropy -= num;
	if (entropy < 0)
	entropy = 0;
	}

	if (do_stir_pool) {
	/*
	* In the output function only half of 'md' remains secret, so we
	* better make sure that the required entropy gets 'evenly
	* distributed' through 'state', our randomness pool. The input
	* function (ssleay_rand_add) chains all of 'md', which makes it more
	* suitable for this purpose.
	*/

	int n = STATE_SIZE; /* so that the complete pool gets accessed */
	while (n > 0) {
	#if MD_DIGEST_LENGTH > 20
	# error "Please adjust DUMMY_SEED."
	#endif
	#define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
	/*
	* Note that the seed does not matter, it's just that
	* ssleay_rand_add expects to have something to hash.
	*/
	ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
	n -= MD_DIGEST_LENGTH;
	}
	if (ok)
	stirred_pool = 1;
	}

	st_idx = state_index;
	st_num = state_num;
	md_c[0] = md_count[0];
	md_c[1] = md_count[1];
	OPENSSL_port_memcpy(local_md, md, sizeof md);

	state_index += num_ceil;
	if (state_index > state_num)
	state_index %= state_num;

	/*
	* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num] are now
	* ours (but other threads may use them too)
	*/

	md_count[0] += 1;

	/* before unlocking, we must clear 'crypto_lock_rand' */
	crypto_lock_rand = 0;
	if (lock)
	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	while (num > 0) {
	/* num_ceil -= MD_DIGEST_LENGTH/2 */
	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);
	MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));

	#ifndef PURIFY /* purify complains */
	/*
	* The following line uses the supplied buffer as a small source of
	* entropy: since this buffer is often uninitialised it may cause
	* programs such as purify or valgrind to complain. So for those
	* builds it is not used: the removal of such a small source of
	* entropy has negligible impact on security.
	*/
	MD_Update(&m, buf, j);
	#endif

	k = (st_idx + MD_DIGEST_LENGTH / 2) - st_num;
	if (k > 0) {
	MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2 - k);
	MD_Update(&m, &(state[0]), k);
	} else
	MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2);
	MD_Final(&m, local_md);

	for (i = 0; i < MD_DIGEST_LENGTH / 2; i++) {
	/* may compete with other threads */
	state[st_idx++] ^= local_md[i];
	if (st_idx >= st_num)
	st_idx = 0;
	if (i < j)
	*(buf++) = local_md[i + MD_DIGEST_LENGTH / 2];
	}
	}

	MD_Init(&m);
	MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));
	MD_Update(&m, local_md, MD_DIGEST_LENGTH);
	if (lock)
	CRYPTO_w_lock(CRYPTO_LOCK_RAND);
	MD_Update(&m, md, MD_DIGEST_LENGTH);
	MD_Final(&m, md);
	if (lock)
	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	EVP_MD_CTX_cleanup(&m);
	if (ok)
	return (1);
	else if (pseudo)
	return 0;
	else {
	RANDerr(RAND_F_SSLEAY_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED);
	ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
	"http://www.openssl.org/support/faq.html");
	return (0);
	}
	}

	static int ssleay_rand_nopseudo_bytes(unsigned char *buf, int num)
	{
	return ssleay_rand_bytes(buf, num, 0, 1);
	}

	/*
	* pseudo-random bytes that are guaranteed to be unique but not unpredictable
	*/
	static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
	{
	return ssleay_rand_bytes(buf, num, 1, 1);
	}

	static int ssleay_rand_status(void)
	{
	CRYPTO_THREADID cur;
	int ret;
	int do_not_lock;

	CRYPTO_THREADID_current(&cur);
	/*
	* check if we already have the lock (could happen if a RAND_poll()
	* implementation calls RAND_status())
	*/
	if (crypto_lock_rand) {
	CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
	do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
	CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
	} else
	do_not_lock = 0;

	if (!do_not_lock) {
	CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	/*
	* prevent ssleay_rand_bytes() from trying to obtain the lock again
	*/
	CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
	CRYPTO_THREADID_cpy(&locking_threadid, &cur);
	CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
	crypto_lock_rand = 1;
	}

	if (!initialized) {
	RAND_poll();
	initialized = 1;
	}

	ret = entropy >= ENTROPY_NEEDED;

	if (!do_not_lock) {
	/* before unlocking, we must clear 'crypto_lock_rand' */
	crypto_lock_rand = 0;

	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
	}

	return ret;
	}