/* 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 <assert.h>

#include <stdio.h>

#include <string.h>

#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 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 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];

    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;

        if (!MD_Init(&m) ||

            !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) ||

                !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)) ||

            !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 (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;

        }

    }

    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

 err:

    EVP_MD_CTX_cleanup(&m);

}

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;

    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

    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];

    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;

        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 (!MD_Update(&m, local_md, MD_DIGEST_LENGTH) ||

            !MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c)))

            goto err;

#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.

         */

        if (!MD_Update(&m, buf, j))

            goto err;

#endif

        k = (st_idx + MD_DIGEST_LENGTH / 2) - st_num;

        if (k > 0) {

            if (!MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2 - k) ||

                !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;

    if (lock)

        CRYPTO_w_lock(CRYPTO_LOCK_RAND);

    if (!MD_Update(&m, md, MD_DIGEST_LENGTH) ||

        !MD_Final(&m, md)) {

        if (lock)

            CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

        goto err;

    }

    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);

    }

 err:

    EVP_MD_CTX_cleanup(&m);

    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;

}