/* 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).
*
*/
#ifdef MD_RAND_DEBUG
# ifndef NDEBUG
# define NDEBUG
# endif
#endif
#include <assert.h>
#include <stdio.h>
#include <string.h>
#include "e_os.h"
#include <openssl/rand.h>
#include "rand_lcl.h"
#include <openssl/crypto.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 */
static unsigned long locking_thread = 0; /* valid iff crypto_lock_rand is set */
#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)
{
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;
/*
* (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_r_lock(CRYPTO_LOCK_RAND2);
do_not_lock = (locking_thread == CRYPTO_thread_id());
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];
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);
MD_Update(&m,buf,j);
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)
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);
}
static int ssleay_rand_bytes(unsigned char *buf, int num)
{
static 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'.
*/
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
/* prevent ssleay_rand_bytes() from trying to obtain the lock again */
CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
locking_thread = CRYPTO_thread_id();
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];
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;
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
MD_Update(&m,buf,j); /* purify complains */
#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++)
{
state[st_idx++]^=local_md[i]; /* may compete with other threads */
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);
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
MD_Update(&m,md,MD_DIGEST_LENGTH);
MD_Final(&m,md);
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
EVP_MD_CTX_cleanup(&m);
if (ok)
return(1);
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);
}
}
/* 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;
unsigned long 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)
ERR_clear_error();
}
return (ret);
}
static int ssleay_rand_status(void)
{
int ret;
int do_not_lock;
/* 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 = (locking_thread == CRYPTO_thread_id());
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);
locking_thread = CRYPTO_thread_id();
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;
}
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