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

 /*
  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the OpenSSL license (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */

 #include <stdio.h>
 #include <string.h>

 #include "e_os.h"

 #if !(defined(OPENSSL_SYS_WIN32) || defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_DSPBIOS))
 # include <sys/time.h>
 #endif
 #if defined(OPENSSL_SYS_VXWORKS)
 # include <time.h>
 #endif

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

 #include <openssl/err.h>

 #include <internal/thread_once.h>

 #if defined(BN_DEBUG) || defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
 # define PREDICT
 #endif

 /* #define PREDICT      1 */

 #define STATE_SIZE      1023
 static size_t 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 CRYPTO_RWLOCK *rand_lock = NULL;
 static CRYPTO_RWLOCK *rand_tmp_lock = NULL;
 static CRYPTO_ONCE rand_lock_init = CRYPTO_ONCE_STATIC_INIT;

 /* May be set only when a thread holds rand_lock (to prevent double locking) */
 static unsigned int crypto_lock_rand = 0;
 /* access to locking_threadid is synchronized by rand_tmp_lock */
 /* valid iff crypto_lock_rand is set */
 static CRYPTO_THREAD_ID locking_threadid;

 #ifdef PREDICT
 int rand_predictable = 0;
 #endif

 static int rand_hw_seed(EVP_MD_CTX *ctx);

 static void rand_cleanup(void);
 static int rand_seed(const void *buf, int num);
 static int rand_add(const void *buf, int num, double add_entropy);
 static int rand_bytes(unsigned char *buf, int num, int pseudo);
 static int rand_nopseudo_bytes(unsigned char *buf, int num);
 #if OPENSSL_API_COMPAT < 0x10100000L
 static int rand_pseudo_bytes(unsigned char *buf, int num);
 #endif
 static int rand_status(void);

 static RAND_METHOD rand_meth = {
     rand_seed,
     rand_nopseudo_bytes,
     rand_cleanup,
     rand_add,
 #if OPENSSL_API_COMPAT < 0x10100000L
     rand_pseudo_bytes,
 #else
     NULL,
 #endif
     rand_status
 };

 DEFINE_RUN_ONCE_STATIC(do_rand_lock_init)
 {
     OPENSSL_init_crypto(0, NULL);
     rand_lock = CRYPTO_THREAD_lock_new();
     rand_tmp_lock = CRYPTO_THREAD_lock_new();
     return rand_lock != NULL && rand_tmp_lock != NULL;
 }

 RAND_METHOD *RAND_OpenSSL(void)
 {
     return (&rand_meth);
 }

 static void 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;
     CRYPTO_THREAD_lock_free(rand_lock);
     CRYPTO_THREAD_lock_free(rand_tmp_lock);
 }

 static int 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;
     int rv = 0;

     if (!num)
         return 1;

 #ifdef PREDICT
     if (rand_predictable)
         return 1;
 #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.
      */

     m = EVP_MD_CTX_new();
     if (m == NULL)
         goto err;

     if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
         goto err;

     /* check if we already have the lock */
     if (crypto_lock_rand) {
         CRYPTO_THREAD_ID cur = CRYPTO_THREAD_get_current_id();
         CRYPTO_THREAD_read_lock(rand_tmp_lock);
         do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
         CRYPTO_THREAD_unlock(rand_tmp_lock);
     } else
         do_not_lock = 0;

     if (!do_not_lock)
         CRYPTO_THREAD_write_lock(rand_lock);
     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);

     if (!do_not_lock)
         CRYPTO_THREAD_unlock(rand_lock);

     for (i = 0; i < num; i += MD_DIGEST_LENGTH) {
         j = (num - i);
         j = (j > MD_DIGEST_LENGTH) ? MD_DIGEST_LENGTH : j;

         if (!MD_Init(m))
             goto err;
         if (!MD_Update(m, local_md, MD_DIGEST_LENGTH))
             goto err;
         k = (st_idx + j) - STATE_SIZE;
         if (k > 0) {
             if (!MD_Update(m, &(state[st_idx]), j - k))
                 goto err;
             if (!MD_Update(m, &(state[0]), k))
                 goto err;
         } else if (!MD_Update(m, &(state[st_idx]), j))
             goto err;

         /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
         if (!MD_Update(m, buf, j))
             goto err;
         /*
          * 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.
          */

         if (!MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c)))
             goto err;
         if (!MD_Final(m, local_md))
             goto err;
         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 (intermediate 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;
         }
     }

     if (!do_not_lock)
         CRYPTO_THREAD_write_lock(rand_lock);
     /*
      * 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_THREAD_unlock(rand_lock);

     rv = 1;
  err:
     EVP_MD_CTX_free(m);
     return rv;
 }

 static int rand_seed(const void *buf, int num)
 {
     return rand_add(buf, num, (double)num);
 }

 static int rand_bytes(unsigned char *buf, int num, int pseudo)
 {
     static volatile int stirred_pool = 0;
     int i, j, k;
     size_t num_ceil, st_idx, st_num;
     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
     time_t curr_time = time(NULL);
     int do_stir_pool = 0;
 /* time value for various platforms */
 #ifdef OPENSSL_SYS_WIN32
     FILETIME tv;
 # ifdef _WIN32_WCE
     SYSTEMTIME t;
     GetSystemTime(&t);
     SystemTimeToFileTime(&t, &tv);
 # else
     GetSystemTimeAsFileTime(&tv);
 # endif
 #elif defined(OPENSSL_SYS_VXWORKS)
     struct timespec tv;
     clock_gettime(CLOCK_REALTIME, &ts);
 #elif defined(OPENSSL_SYS_DSPBIOS)
     unsigned long long tv, OPENSSL_rdtsc();
     tv = OPENSSL_rdtsc();
 #else
     struct timeval tv;
     gettimeofday(&tv, NULL);
 #endif

 #ifdef PREDICT
     if (rand_predictable) {
         unsigned char val = 1;

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

     if (num <= 0)
         return 1;

     m = EVP_MD_CTX_new();
     if (m == NULL)
         goto err_mem;

     /* 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 (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
         goto err_mem;

     CRYPTO_THREAD_write_lock(rand_lock);
     /*
      * We could end up in an async engine while holding this lock so ensure
      * we don't pause and cause a deadlock
      */
     ASYNC_block_pause();

     /* prevent rand_bytes() from trying to obtain the lock again */
     CRYPTO_THREAD_write_lock(rand_tmp_lock);
     locking_threadid = CRYPTO_THREAD_get_current_id();
     CRYPTO_THREAD_unlock(rand_tmp_lock);
     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 (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
              * rand_add expects to have something to hash.
              */
             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];
     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;
     ASYNC_unblock_pause();
     CRYPTO_THREAD_unlock(rand_lock);

     while (num > 0) {
         /* num_ceil -= MD_DIGEST_LENGTH/2 */
         j = (num >= MD_DIGEST_LENGTH / 2) ? MD_DIGEST_LENGTH / 2 : num;
         num -= j;
         if (!MD_Init(m))
             goto err;
 #ifndef GETPID_IS_MEANINGLESS
         if (curr_pid) {         /* just in the first iteration to save time */
             if (!MD_Update(m, (unsigned char *)&curr_pid, sizeof curr_pid))
                 goto err;
             curr_pid = 0;
         }
 #endif
         if (curr_time) {        /* just in the first iteration to save time */
             if (!MD_Update(m, (unsigned char *)&curr_time, sizeof curr_time))
                 goto err;
             if (!MD_Update(m, (unsigned char *)&tv, sizeof tv))
                 goto err;
             curr_time = 0;
             if (!rand_hw_seed(m))
                 goto err;
         }
         if (!MD_Update(m, local_md, MD_DIGEST_LENGTH))
             goto err;
         if (!MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c)))
             goto err;

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

         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];
         }
     }

     if (!MD_Init(m)
         || !MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c))
         || !MD_Update(m, local_md, MD_DIGEST_LENGTH))
         goto err;
     CRYPTO_THREAD_write_lock(rand_lock);
     /*
      * Prevent deadlocks if we end up in an async engine
      */
     ASYNC_block_pause();
     if (!MD_Update(m, md, MD_DIGEST_LENGTH) || !MD_Final(m, md)) {
         CRYPTO_THREAD_unlock(rand_lock);
         goto err;
     }
     ASYNC_unblock_pause();
     CRYPTO_THREAD_unlock(rand_lock);

     EVP_MD_CTX_free(m);
     if (ok)
         return (1);
     else if (pseudo)
         return 0;
     else {
         RANDerr(RAND_F_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED);
         ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
                            "https://www.openssl.org/docs/faq.html");
         return (0);
     }
  err:
     RANDerr(RAND_F_RAND_BYTES, ERR_R_EVP_LIB);
     EVP_MD_CTX_free(m);
     return 0;
  err_mem:
     RANDerr(RAND_F_RAND_BYTES, ERR_R_MALLOC_FAILURE);
     EVP_MD_CTX_free(m);
     return 0;

 }

 static int rand_nopseudo_bytes(unsigned char *buf, int num)
 {
     return rand_bytes(buf, num, 0);
 }

 #if OPENSSL_API_COMPAT < 0x10100000L
 /*
  * pseudo-random bytes that are guaranteed to be unique but not unpredictable
  */
 static int rand_pseudo_bytes(unsigned char *buf, int num)
 {
     return rand_bytes(buf, num, 1);
 }
 #endif

 static int rand_status(void)
 {
     CRYPTO_THREAD_ID cur;
     int ret;
     int do_not_lock;

     if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
         return 0;

     cur = CRYPTO_THREAD_get_current_id();
     /*
      * check if we already have the lock (could happen if a RAND_poll()
      * implementation calls RAND_status())
      */
     if (crypto_lock_rand) {
         CRYPTO_THREAD_read_lock(rand_tmp_lock);
         do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
         CRYPTO_THREAD_unlock(rand_tmp_lock);
     } else
         do_not_lock = 0;

     if (!do_not_lock) {
         CRYPTO_THREAD_write_lock(rand_lock);
         /*
          * Prevent deadlocks in case we end up in an async engine
          */
         ASYNC_block_pause();

         /*
          * prevent rand_bytes() from trying to obtain the lock again
          */
         CRYPTO_THREAD_write_lock(rand_tmp_lock);
         locking_threadid = cur;
         CRYPTO_THREAD_unlock(rand_tmp_lock);
         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;

         ASYNC_unblock_pause();
         CRYPTO_THREAD_unlock(rand_lock);
     }

     return ret;
 }

 /*
  * rand_hw_seed: get seed data from any available hardware RNG. only
  * currently supports rdrand.
  */

 /* Adapted from eng_rdrand.c */

 #if (defined(__i386)   || defined(__i386__)   || defined(_M_IX86) || \
      defined(__x86_64) || defined(__x86_64__) || \
      defined(_M_AMD64) || defined (_M_X64)) && defined(OPENSSL_CPUID_OBJ) \
      && !defined(OPENSSL_NO_RDRAND)

 # define RDRAND_CALLS    4

 size_t OPENSSL_ia32_rdrand(void);
 extern unsigned int OPENSSL_ia32cap_P[];

 static int rand_hw_seed(EVP_MD_CTX *ctx)
 {
     int i;
     if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32))))
         return 1;
     for (i = 0; i < RDRAND_CALLS; i++) {
         size_t rnd;
         rnd = OPENSSL_ia32_rdrand();
         if (rnd == 0)
             return 1;
         if (!MD_Update(ctx, (unsigned char *)&rnd, sizeof(size_t)))
             return 0;
     }
     return 1;
 }

 /* XOR an existing buffer with random data */

 void rand_hw_xor(unsigned char *buf, size_t num)
 {
     size_t rnd;
     if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32))))
         return;
     while (num >= sizeof(size_t)) {
         rnd = OPENSSL_ia32_rdrand();
         if (rnd == 0)
             return;
         *((size_t *)buf) ^= rnd;
         buf += sizeof(size_t);
         num -= sizeof(size_t);
     }
     if (num) {
         rnd = OPENSSL_ia32_rdrand();
         if (rnd == 0)
             return;
         while (num) {
             *buf ^= rnd & 0xff;
             rnd >>= 8;
             buf++;
             num--;
         }
     }
 }

 #else

 static int rand_hw_seed(EVP_MD_CTX *ctx)
 {
     return 1;
 }

 void rand_hw_xor(unsigned char *buf, size_t num)
 {
     return;
 }

 #endif
	/*
	* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
	*
	* Licensed under the OpenSSL license (the "License"). You may not use
	* this file except in compliance with the License. You can obtain a copy
	* in the file LICENSE in the source distribution or at
	* https://www.openssl.org/source/license.html
	*/

	#include <stdio.h>
	#include <string.h>

	#include "e_os.h"

	#if !(defined(OPENSSL_SYS_WIN32) \|\| defined(OPENSSL_SYS_VXWORKS) \|\| defined(OPENSSL_SYS_DSPBIOS))
	# include <sys/time.h>
	#endif
	#if defined(OPENSSL_SYS_VXWORKS)
	# include <time.h>
	#endif

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

	#include <openssl/err.h>

	#include <internal/thread_once.h>

	#if defined(BN_DEBUG) \|\| defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
	# define PREDICT
	#endif

	/* #define PREDICT 1 */

	#define STATE_SIZE 1023
	static size_t 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 CRYPTO_RWLOCK *rand_lock = NULL;
	static CRYPTO_RWLOCK *rand_tmp_lock = NULL;
	static CRYPTO_ONCE rand_lock_init = CRYPTO_ONCE_STATIC_INIT;

	/* May be set only when a thread holds rand_lock (to prevent double locking) */
	static unsigned int crypto_lock_rand = 0;
	/* access to locking_threadid is synchronized by rand_tmp_lock */
	/* valid iff crypto_lock_rand is set */
	static CRYPTO_THREAD_ID locking_threadid;

	#ifdef PREDICT
	int rand_predictable = 0;
	#endif

	static int rand_hw_seed(EVP_MD_CTX *ctx);

	static void rand_cleanup(void);
	static int rand_seed(const void *buf, int num);
	static int rand_add(const void *buf, int num, double add_entropy);
	static int rand_bytes(unsigned char *buf, int num, int pseudo);
	static int rand_nopseudo_bytes(unsigned char *buf, int num);
	#if OPENSSL_API_COMPAT < 0x10100000L
	static int rand_pseudo_bytes(unsigned char *buf, int num);
	#endif
	static int rand_status(void);

	static RAND_METHOD rand_meth = {
	rand_seed,
	rand_nopseudo_bytes,
	rand_cleanup,
	rand_add,
	#if OPENSSL_API_COMPAT < 0x10100000L
	rand_pseudo_bytes,
	#else
	NULL,
	#endif
	rand_status
	};

	DEFINE_RUN_ONCE_STATIC(do_rand_lock_init)
	{
	OPENSSL_init_crypto(0, NULL);
	rand_lock = CRYPTO_THREAD_lock_new();
	rand_tmp_lock = CRYPTO_THREAD_lock_new();
	return rand_lock != NULL && rand_tmp_lock != NULL;
	}

	RAND_METHOD *RAND_OpenSSL(void)
	{
	return (&rand_meth);
	}

	static void 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;
	CRYPTO_THREAD_lock_free(rand_lock);
	CRYPTO_THREAD_lock_free(rand_tmp_lock);
	}

	static int 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;
	int rv = 0;

	if (!num)
	return 1;

	#ifdef PREDICT
	if (rand_predictable)
	return 1;
	#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.
	*/

	m = EVP_MD_CTX_new();
	if (m == NULL)
	goto err;

	if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
	goto err;

	/* check if we already have the lock */
	if (crypto_lock_rand) {
	CRYPTO_THREAD_ID cur = CRYPTO_THREAD_get_current_id();
	CRYPTO_THREAD_read_lock(rand_tmp_lock);
	do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
	CRYPTO_THREAD_unlock(rand_tmp_lock);
	} else
	do_not_lock = 0;

	if (!do_not_lock)
	CRYPTO_THREAD_write_lock(rand_lock);
	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);

	if (!do_not_lock)
	CRYPTO_THREAD_unlock(rand_lock);

	for (i = 0; i < num; i += MD_DIGEST_LENGTH) {
	j = (num - i);
	j = (j > MD_DIGEST_LENGTH) ? MD_DIGEST_LENGTH : j;

	if (!MD_Init(m))
	goto err;
	if (!MD_Update(m, local_md, MD_DIGEST_LENGTH))
	goto err;
	k = (st_idx + j) - STATE_SIZE;
	if (k > 0) {
	if (!MD_Update(m, &(state[st_idx]), j - k))
	goto err;
	if (!MD_Update(m, &(state[0]), k))
	goto err;
	} else if (!MD_Update(m, &(state[st_idx]), j))
	goto err;

	/* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
	if (!MD_Update(m, buf, j))
	goto err;
	/*
	* 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.
	*/

	if (!MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c)))
	goto err;
	if (!MD_Final(m, local_md))
	goto err;
	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 (intermediate 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;
	}
	}

	if (!do_not_lock)
	CRYPTO_THREAD_write_lock(rand_lock);
	/*
	* 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_THREAD_unlock(rand_lock);

	rv = 1;
	err:
	EVP_MD_CTX_free(m);
	return rv;
	}

	static int rand_seed(const void *buf, int num)
	{
	return rand_add(buf, num, (double)num);
	}

	static int rand_bytes(unsigned char *buf, int num, int pseudo)
	{
	static volatile int stirred_pool = 0;
	int i, j, k;
	size_t num_ceil, st_idx, st_num;
	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
	time_t curr_time = time(NULL);
	int do_stir_pool = 0;
	/* time value for various platforms */
	#ifdef OPENSSL_SYS_WIN32
	FILETIME tv;
	# ifdef _WIN32_WCE
	SYSTEMTIME t;
	GetSystemTime(&t);
	SystemTimeToFileTime(&t, &tv);
	# else
	GetSystemTimeAsFileTime(&tv);
	# endif
	#elif defined(OPENSSL_SYS_VXWORKS)
	struct timespec tv;
	clock_gettime(CLOCK_REALTIME, &ts);
	#elif defined(OPENSSL_SYS_DSPBIOS)
	unsigned long long tv, OPENSSL_rdtsc();
	tv = OPENSSL_rdtsc();
	#else
	struct timeval tv;
	gettimeofday(&tv, NULL);
	#endif

	#ifdef PREDICT
	if (rand_predictable) {
	unsigned char val = 1;

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

	if (num <= 0)
	return 1;

	m = EVP_MD_CTX_new();
	if (m == NULL)
	goto err_mem;

	/* 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 (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
	goto err_mem;

	CRYPTO_THREAD_write_lock(rand_lock);
	/*
	* We could end up in an async engine while holding this lock so ensure
	* we don't pause and cause a deadlock
	*/
	ASYNC_block_pause();

	/* prevent rand_bytes() from trying to obtain the lock again */
	CRYPTO_THREAD_write_lock(rand_tmp_lock);
	locking_threadid = CRYPTO_THREAD_get_current_id();
	CRYPTO_THREAD_unlock(rand_tmp_lock);
	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 (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
	* rand_add expects to have something to hash.
	*/
	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];
	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;
	ASYNC_unblock_pause();
	CRYPTO_THREAD_unlock(rand_lock);

	while (num > 0) {
	/* num_ceil -= MD_DIGEST_LENGTH/2 */
	j = (num >= MD_DIGEST_LENGTH / 2) ? MD_DIGEST_LENGTH / 2 : num;
	num -= j;
	if (!MD_Init(m))
	goto err;
	#ifndef GETPID_IS_MEANINGLESS
	if (curr_pid) { /* just in the first iteration to save time */
	if (!MD_Update(m, (unsigned char *)&curr_pid, sizeof curr_pid))
	goto err;
	curr_pid = 0;
	}
	#endif
	if (curr_time) { /* just in the first iteration to save time */
	if (!MD_Update(m, (unsigned char *)&curr_time, sizeof curr_time))
	goto err;
	if (!MD_Update(m, (unsigned char *)&tv, sizeof tv))
	goto err;
	curr_time = 0;
	if (!rand_hw_seed(m))
	goto err;
	}
	if (!MD_Update(m, local_md, MD_DIGEST_LENGTH))
	goto err;
	if (!MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c)))
	goto err;

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

	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];
	}
	}

	if (!MD_Init(m)
	\|\| !MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c))
	\|\| !MD_Update(m, local_md, MD_DIGEST_LENGTH))
	goto err;
	CRYPTO_THREAD_write_lock(rand_lock);
	/*
	* Prevent deadlocks if we end up in an async engine
	*/
	ASYNC_block_pause();
	if (!MD_Update(m, md, MD_DIGEST_LENGTH) \|\| !MD_Final(m, md)) {
	CRYPTO_THREAD_unlock(rand_lock);
	goto err;
	}
	ASYNC_unblock_pause();
	CRYPTO_THREAD_unlock(rand_lock);

	EVP_MD_CTX_free(m);
	if (ok)
	return (1);
	else if (pseudo)
	return 0;
	else {
	RANDerr(RAND_F_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED);
	ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
	"https://www.openssl.org/docs/faq.html");
	return (0);
	}
	err:
	RANDerr(RAND_F_RAND_BYTES, ERR_R_EVP_LIB);
	EVP_MD_CTX_free(m);
	return 0;
	err_mem:
	RANDerr(RAND_F_RAND_BYTES, ERR_R_MALLOC_FAILURE);
	EVP_MD_CTX_free(m);
	return 0;

	}

	static int rand_nopseudo_bytes(unsigned char *buf, int num)
	{
	return rand_bytes(buf, num, 0);
	}

	#if OPENSSL_API_COMPAT < 0x10100000L
	/*
	* pseudo-random bytes that are guaranteed to be unique but not unpredictable
	*/
	static int rand_pseudo_bytes(unsigned char *buf, int num)
	{
	return rand_bytes(buf, num, 1);
	}
	#endif

	static int rand_status(void)
	{
	CRYPTO_THREAD_ID cur;
	int ret;
	int do_not_lock;

	if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
	return 0;

	cur = CRYPTO_THREAD_get_current_id();
	/*
	* check if we already have the lock (could happen if a RAND_poll()
	* implementation calls RAND_status())
	*/
	if (crypto_lock_rand) {
	CRYPTO_THREAD_read_lock(rand_tmp_lock);
	do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
	CRYPTO_THREAD_unlock(rand_tmp_lock);
	} else
	do_not_lock = 0;

	if (!do_not_lock) {
	CRYPTO_THREAD_write_lock(rand_lock);
	/*
	* Prevent deadlocks in case we end up in an async engine
	*/
	ASYNC_block_pause();

	/*
	* prevent rand_bytes() from trying to obtain the lock again
	*/
	CRYPTO_THREAD_write_lock(rand_tmp_lock);
	locking_threadid = cur;
	CRYPTO_THREAD_unlock(rand_tmp_lock);
	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;

	ASYNC_unblock_pause();
	CRYPTO_THREAD_unlock(rand_lock);
	}

	return ret;
	}

	/*
	* rand_hw_seed: get seed data from any available hardware RNG. only
	* currently supports rdrand.
	*/

	/* Adapted from eng_rdrand.c */

	#if (defined(__i386) \|\| defined(__i386__) \|\| defined(_M_IX86) \|\| \
	defined(__x86_64) \|\| defined(__x86_64__) \|\| \
	defined(_M_AMD64) \|\| defined (_M_X64)) && defined(OPENSSL_CPUID_OBJ) \
	&& !defined(OPENSSL_NO_RDRAND)

	# define RDRAND_CALLS 4

	size_t OPENSSL_ia32_rdrand(void);
	extern unsigned int OPENSSL_ia32cap_P[];

	static int rand_hw_seed(EVP_MD_CTX *ctx)
	{
	int i;
	if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32))))
	return 1;
	for (i = 0; i < RDRAND_CALLS; i++) {
	size_t rnd;
	rnd = OPENSSL_ia32_rdrand();
	if (rnd == 0)
	return 1;
	if (!MD_Update(ctx, (unsigned char *)&rnd, sizeof(size_t)))
	return 0;
	}
	return 1;
	}

	/* XOR an existing buffer with random data */

	void rand_hw_xor(unsigned char *buf, size_t num)
	{
	size_t rnd;
	if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32))))
	return;
	while (num >= sizeof(size_t)) {
	rnd = OPENSSL_ia32_rdrand();
	if (rnd == 0)
	return;
	((size_t )buf) ^= rnd;
	buf += sizeof(size_t);
	num -= sizeof(size_t);
	}
	if (num) {
	rnd = OPENSSL_ia32_rdrand();
	if (rnd == 0)
	return;
	while (num) {
	*buf ^= rnd & 0xff;
	rnd >>= 8;
	buf++;
	num--;
	}
	}
	}

	#else

	static int rand_hw_seed(EVP_MD_CTX *ctx)
	{
	return 1;
	}

	void rand_hw_xor(unsigned char *buf, size_t num)
	{
	return;
	}

	#endif