wolfssl/wolfcrypt/src/random.c

/* random.c
 *
 * Copyright (C) 2006-2022 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */

/*

DESCRIPTION
This library contains implementation for the random number generator.

*/
#ifdef HAVE_CONFIG_H
    #include <config.h>
#endif

#include <wolfssl/wolfcrypt/settings.h>
#include <wolfssl/wolfcrypt/error-crypt.h>

/* on HPUX 11 you may need to install /dev/random see
   http://h20293.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=KRNG11I

*/

#if defined(HAVE_FIPS) && \
    defined(HAVE_FIPS_VERSION) && (HAVE_FIPS_VERSION >= 2)

    /* set NO_WRAPPERS before headers, use direct internal f()s not wrappers */
    #define FIPS_NO_WRAPPERS

    #ifdef USE_WINDOWS_API
        #pragma code_seg(".fipsA$c")
        #pragma const_seg(".fipsB$c")
    #endif
#endif


#include <wolfssl/wolfcrypt/random.h>
#include <wolfssl/wolfcrypt/cpuid.h>


/* If building for old FIPS. */
#if defined(HAVE_FIPS) && \
    (!defined(HAVE_FIPS_VERSION) || (HAVE_FIPS_VERSION < 2))

int wc_GenerateSeed(OS_Seed* os, byte* seed, word32 sz)
{
    return GenerateSeed(os, seed, sz);
}

int wc_InitRng_ex(WC_RNG* rng, void* heap, int devId)
{
    (void)heap;
    (void)devId;
    return InitRng_fips(rng);
}

WOLFSSL_ABI
int wc_InitRng(WC_RNG* rng)
{
    return InitRng_fips(rng);
}


int wc_RNG_GenerateBlock(WC_RNG* rng, byte* b, word32 sz)
{
    return RNG_GenerateBlock_fips(rng, b, sz);
}


int wc_RNG_GenerateByte(WC_RNG* rng, byte* b)
{
    return RNG_GenerateByte(rng, b);
}

#ifdef HAVE_HASHDRBG

    int wc_FreeRng(WC_RNG* rng)
    {
        return FreeRng_fips(rng);
    }

    int wc_RNG_HealthTest(int reseed, const byte* seedA, word32 seedASz,
                                      const byte* seedB, word32 seedBSz,
                                      byte* output, word32 outputSz)
    {
        return RNG_HealthTest_fips(reseed, seedA, seedASz,
                              seedB, seedBSz, output, outputSz);
   }
#endif /* HAVE_HASHDRBG */

#else /* else build without fips, or for new fips */

#ifndef WC_NO_RNG /* if not FIPS and RNG is disabled then do not compile */

#include <wolfssl/wolfcrypt/sha256.h>

#ifdef WOLF_CRYPTO_CB
    #include <wolfssl/wolfcrypt/cryptocb.h>
#endif

#ifdef NO_INLINE
    #include <wolfssl/wolfcrypt/misc.h>
#else
    #define WOLFSSL_MISC_INCLUDED
    #include <wolfcrypt/src/misc.c>
#endif

#if defined(WOLFSSL_SGX)
    #include <sgx_trts.h>
#elif defined(USE_WINDOWS_API)
    #ifndef _WIN32_WINNT
        #define _WIN32_WINNT 0x0400
    #endif
    #include <windows.h>
    #include <wincrypt.h>
#elif defined(HAVE_WNR)
    #include <wnr.h>
    #include <wolfssl/wolfcrypt/logging.h>
    wolfSSL_Mutex wnr_mutex;    /* global netRandom mutex */
    int wnr_timeout     = 0;    /* entropy timeout, milliseconds */
    int wnr_mutex_init  = 0;    /* flag for mutex init */
    wnr_context*  wnr_ctx;      /* global netRandom context */
#elif defined(FREESCALE_KSDK_2_0_TRNG)
    #include "fsl_trng.h"
#elif defined(FREESCALE_KSDK_2_0_RNGA)
    #include "fsl_rnga.h"
#elif defined(WOLFSSL_WICED)
    #include "wiced_crypto.h"
#elif defined(WOLFSSL_NETBURNER)
    #include <predef.h>
    #include <basictypes.h>
    #include <random.h>
#elif defined(WOLFSSL_XILINX_CRYPT_VERSAL)
#include "wolfssl/wolfcrypt/port/xilinx/xil-versal-trng.h"
#elif defined(NO_DEV_RANDOM)
#elif defined(CUSTOM_RAND_GENERATE)
#elif defined(CUSTOM_RAND_GENERATE_BLOCK)
#elif defined(CUSTOM_RAND_GENERATE_SEED)
#elif defined(WOLFSSL_GENSEED_FORTEST)
#elif defined(WOLFSSL_MDK_ARM)
#elif defined(WOLFSSL_IAR_ARM)
#elif defined(WOLFSSL_ROWLEY_ARM)
#elif defined(WOLFSSL_EMBOS)
#elif defined(WOLFSSL_DEOS)
#elif defined(MICRIUM)
#elif defined(WOLFSSL_NUCLEUS)
#elif defined(WOLFSSL_PB)
#elif defined(WOLFSSL_ZEPHYR)
#elif defined(WOLFSSL_TELIT_M2MB)
#elif defined(WOLFSSL_SCE) && !defined(WOLFSSL_SCE_NO_TRNG)
#elif defined(WOLFSSL_GETRANDOM)
    #include <errno.h>
    #include <sys/random.h>
#else
    /* include headers that may be needed to get good seed */
    #include <fcntl.h>
    #ifndef EBSNET
        #include <unistd.h>
    #endif
#endif

#if defined(WOLFSSL_SILABS_SE_ACCEL)
#include <wolfssl/wolfcrypt/port/silabs/silabs_random.h>
#endif

#if defined(WOLFSSL_IOTSAFE) && defined(HAVE_IOTSAFE_HWRNG)
#include <wolfssl/wolfcrypt/port/iotsafe/iotsafe.h>
#endif

#if defined(WOLFSSL_HAVE_PSA) && !defined(WOLFSSL_PSA_NO_RNG)
#include <wolfssl/wolfcrypt/port/psa/psa.h>
#endif

#if defined(HAVE_INTEL_RDRAND) || defined(HAVE_INTEL_RDSEED) || \
    defined(HAVE_AMD_RDSEED)
    static word32 intel_flags = 0;
    static void wc_InitRng_IntelRD(void)
    {
        intel_flags = cpuid_get_flags();
    }
    #if (defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)) && \
        !defined(WOLFSSL_LINUXKM)
    static int wc_GenerateSeed_IntelRD(OS_Seed* os, byte* output, word32 sz);
    #endif
    #ifdef HAVE_INTEL_RDRAND
    static int wc_GenerateRand_IntelRD(OS_Seed* os, byte* output, word32 sz);
    #endif

#ifdef USE_WINDOWS_API
    #define USE_INTEL_INTRINSICS
#elif !defined __GNUC__ || defined __clang__ || __GNUC__ > 4
    #define USE_INTEL_INTRINSICS
#else
    #undef USE_INTEL_INTRINSICS
#endif

#ifdef USE_INTEL_INTRINSICS
    #include <immintrin.h>
    /* Before clang 7 or GCC 9, immintrin.h did not define _rdseed64_step() */
    #ifndef HAVE_INTEL_RDSEED
    #elif defined __clang__ && __clang_major__ > 6
    #elif !defined __GNUC__
    #elif __GNUC__ > 8
    #else
        #ifndef __clang__
            #pragma GCC push_options
            #pragma GCC target("rdseed")
        #else
            #define __RDSEED__
        #endif
        #include <x86intrin.h>
        #ifndef __clang__
            #pragma GCC pop_options
        #endif
    #endif
#endif /* USE_WINDOWS_API */
#endif

/* Start NIST DRBG code */
#ifdef HAVE_HASHDRBG

#define OUTPUT_BLOCK_LEN  (WC_SHA256_DIGEST_SIZE)
#define MAX_REQUEST_LEN   (0x10000)
#define RESEED_INTERVAL   WC_RESEED_INTERVAL


/* The security strength for the RNG is the target number of bits of
 * entropy you are looking for in a seed. */
#ifndef RNG_SECURITY_STRENGTH
    /* SHA-256 requires a minimum of 256-bits of entropy. */
    #define RNG_SECURITY_STRENGTH (256)
#endif

#ifndef ENTROPY_SCALE_FACTOR
    /* The entropy scale factor should be the whole number inverse of the
     * minimum bits of entropy per bit of NDRNG output. */
    #if defined(HAVE_AMD_RDSEED)
        /* This will yield a SEED_SZ of 16kb. Since nonceSz will be 0,
         * we'll add an additional 8kb on top. */
        #define ENTROPY_SCALE_FACTOR  (512)
    #elif defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND)
        /* The value of 2 applies to Intel's RDSEED which provides about
         * 0.5 bits minimum of entropy per bit. The value of 4 gives a
         * conservative margin for FIPS. */
        #if defined(HAVE_FIPS) && defined(HAVE_FIPS_VERSION) && \
            (HAVE_FIPS_VERSION >= 2)
            #define ENTROPY_SCALE_FACTOR (2*4)
        #else
            /* Not FIPS, but Intel RDSEED, only double. */
            #define ENTROPY_SCALE_FACTOR (2)
        #endif
    #elif defined(HAVE_FIPS) && defined(HAVE_FIPS_VERSION) && \
        (HAVE_FIPS_VERSION >= 2)
        /* If doing a FIPS build without a specific scale factor, default
         * to 4. This will give 1024 bits of entropy. More is better, but
         * more is also slower. */
        #define ENTROPY_SCALE_FACTOR (4)
    #else
        /* Setting the default to 1. */
        #define ENTROPY_SCALE_FACTOR (1)
    #endif
#endif

#ifndef SEED_BLOCK_SZ
    /* The seed block size, is the size of the output of the underlying NDRNG.
     * This value is used for testing the output of the NDRNG. */
    #if defined(HAVE_AMD_RDSEED)
        /* AMD's RDSEED instruction works in 128-bit blocks read 64-bits
        * at a time. */
        #define SEED_BLOCK_SZ (sizeof(word64)*2)
    #elif defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND)
        /* RDSEED outputs in blocks of 64-bits. */
        #define SEED_BLOCK_SZ sizeof(word64)
    #else
        /* Setting the default to 4. */
        #define SEED_BLOCK_SZ 4
    #endif
#endif

#define SEED_SZ        (RNG_SECURITY_STRENGTH*ENTROPY_SCALE_FACTOR/8)

/* The maximum seed size will be the seed size plus a seed block for the
 * test, and an additional half of the seed size. This additional half
 * is in case the user does not supply a nonce. A nonce will be obtained
 * from the NDRNG. */
#define MAX_SEED_SZ    (SEED_SZ + SEED_SZ/2 + SEED_BLOCK_SZ)


#ifdef WC_RNG_SEED_CB

static wc_RngSeed_Cb seedCb = NULL;

int wc_SetSeed_Cb(wc_RngSeed_Cb cb)
{
    seedCb = cb;
    return 0;
}

#endif


/* Internal return codes */
#define DRBG_SUCCESS      0
#define DRBG_FAILURE      1
#define DRBG_NEED_RESEED  2
#define DRBG_CONT_FAILURE 3
#define DRBG_NO_SEED_CB   4

/* RNG health states */
#define DRBG_NOT_INIT     0
#define DRBG_OK           1
#define DRBG_FAILED       2
#define DRBG_CONT_FAILED  3

#define RNG_HEALTH_TEST_CHECK_SIZE (WC_SHA256_DIGEST_SIZE * 4)

/* Verify max gen block len */
#if RNG_MAX_BLOCK_LEN > MAX_REQUEST_LEN
    #error RNG_MAX_BLOCK_LEN is larger than NIST DBRG max request length
#endif

enum {
    drbgInitC     = 0,
    drbgReseed    = 1,
    drbgGenerateW = 2,
    drbgGenerateH = 3,
    drbgInitV     = 4
};

typedef struct DRBG_internal DRBG_internal;

static int wc_RNG_HealthTestLocal(int reseed);

/* Hash Derivation Function */
/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static int Hash_df(DRBG_internal* drbg, byte* out, word32 outSz, byte type,
                                                  const byte* inA, word32 inASz,
                                                  const byte* inB, word32 inBSz)
{
    int ret = DRBG_FAILURE;
    byte ctr;
    int i;
    int len;
    word32 bits = (outSz * 8); /* reverse byte order */
#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha256* sha = &drbg->sha256;
#else
    wc_Sha256 sha[1];
#endif
#ifdef WC_ASYNC_ENABLE_SHA256
    WC_DECLARE_VAR(digest, byte, WC_SHA256_DIGEST_SIZE, drbg->heap);
    if (digest == NULL)
        return MEMORY_E;
#else
    byte digest[WC_SHA256_DIGEST_SIZE];
#endif

    (void)drbg;
#ifdef WC_ASYNC_ENABLE_SHA256
    if (digest == NULL)
        return DRBG_FAILURE;
#endif

#ifdef LITTLE_ENDIAN_ORDER
    bits = ByteReverseWord32(bits);
#endif
    len = (outSz / OUTPUT_BLOCK_LEN)
        + ((outSz % OUTPUT_BLOCK_LEN) ? 1 : 0);

    ctr = 1;
    for (i = 0; i < len; i++) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha256_ex(sha, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha256(sha);
    #endif
        if (ret != 0)
            break;
#endif
        ret = wc_Sha256Update(sha, &ctr, sizeof(ctr));
        if (ret == 0) {
            ctr++;
            ret = wc_Sha256Update(sha, (byte*)&bits, sizeof(bits));
        }

        if (ret == 0) {
            /* churning V is the only string that doesn't have the type added */
            if (type != drbgInitV)
                ret = wc_Sha256Update(sha, &type, sizeof(type));
        }
        if (ret == 0)
            ret = wc_Sha256Update(sha, inA, inASz);
        if (ret == 0) {
            if (inB != NULL && inBSz > 0)
                ret = wc_Sha256Update(sha, inB, inBSz);
        }
        if (ret == 0)
            ret = wc_Sha256Final(sha, digest);

#ifndef WOLFSSL_SMALL_STACK_CACHE
        wc_Sha256Free(sha);
#endif
        if (ret == 0) {
            if (outSz > OUTPUT_BLOCK_LEN) {
                XMEMCPY(out, digest, OUTPUT_BLOCK_LEN);
                outSz -= OUTPUT_BLOCK_LEN;
                out += OUTPUT_BLOCK_LEN;
            }
            else {
                XMEMCPY(out, digest, outSz);
            }
        }
    }

    ForceZero(digest, WC_SHA256_DIGEST_SIZE);

#ifdef WC_ASYNC_ENABLE_SHA256
    WC_FREE_VAR(digest, drbg->heap);
#endif

    return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static int Hash_DRBG_Reseed(DRBG_internal* drbg, const byte* seed, word32 seedSz)
{
    byte newV[DRBG_SEED_LEN];

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

    XMEMSET(newV, 0, DRBG_SEED_LEN);

    if (Hash_df(drbg, newV, sizeof(newV), drbgReseed,
                drbg->V, sizeof(drbg->V), seed, seedSz) != DRBG_SUCCESS) {
        return DRBG_FAILURE;
    }

    XMEMCPY(drbg->V, newV, sizeof(drbg->V));
    ForceZero(newV, sizeof(newV));

    if (Hash_df(drbg, drbg->C, sizeof(drbg->C), drbgInitC, drbg->V,
                                    sizeof(drbg->V), NULL, 0) != DRBG_SUCCESS) {
        return DRBG_FAILURE;
    }

    drbg->reseedCtr = 1;
    drbg->lastBlock = 0;
    drbg->matchCount = 0;
    return DRBG_SUCCESS;
}

/* Returns: DRBG_SUCCESS and DRBG_FAILURE or BAD_FUNC_ARG on fail */
int wc_RNG_DRBG_Reseed(WC_RNG* rng, const byte* seed, word32 seedSz)
{
    if (rng == NULL || seed == NULL) {
        return BAD_FUNC_ARG;
    }

    if (rng->drbg == NULL) {
    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND)
        if (IS_INTEL_RDRAND(intel_flags)) {
            /* using RDRAND not DRBG, so return success */
            return 0;
        }
        return BAD_FUNC_ARG;
    #endif
    }

    return Hash_DRBG_Reseed((DRBG_internal *)rng->drbg, seed, seedSz);
}

static WC_INLINE void array_add_one(byte* data, word32 dataSz)
{
    int i;

    for (i = dataSz - 1; i >= 0; i--)
    {
        data[i]++;
        if (data[i] != 0) break;
    }
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static int Hash_gen(DRBG_internal* drbg, byte* out, word32 outSz, const byte* V)
{
    int ret = DRBG_FAILURE;
    byte data[DRBG_SEED_LEN];
    int i;
    int len;
    word32 checkBlock;
#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha256* sha = &drbg->sha256;
#else
    wc_Sha256 sha[1];
#endif
#ifdef WC_ASYNC_ENABLE_SHA256
    WC_DECLARE_VAR(digest, byte, WC_SHA256_DIGEST_SIZE, drbg->heap);
    if (digest == NULL)
        return MEMORY_E;
#else
    byte digest[WC_SHA256_DIGEST_SIZE];
#endif

    /* Special case: outSz is 0 and out is NULL. wc_Generate a block to save for
     * the continuous test. */

    if (outSz == 0) outSz = 1;

    len = (outSz / OUTPUT_BLOCK_LEN) + ((outSz % OUTPUT_BLOCK_LEN) ? 1 : 0);

    XMEMCPY(data, V, sizeof(data));
    for (i = 0; i < len; i++) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha256_ex(sha, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha256(sha);
    #endif
        if (ret == 0)
#endif
            ret = wc_Sha256Update(sha, data, sizeof(data));
        if (ret == 0)
            ret = wc_Sha256Final(sha, digest);
#ifndef WOLFSSL_SMALL_STACK_CACHE
        wc_Sha256Free(sha);
#endif

        if (ret == 0) {
            XMEMCPY(&checkBlock, digest, sizeof(word32));
            if (drbg->reseedCtr > 1 && checkBlock == drbg->lastBlock) {
                if (drbg->matchCount == 1) {
                    return DRBG_CONT_FAILURE;
                }
                else {
                    if (i == (len-1)) {
                        len++;
                    }
                    drbg->matchCount = 1;
                }
            }
            else {
                drbg->matchCount = 0;
                drbg->lastBlock = checkBlock;
            }

            if (out != NULL && outSz != 0) {
                if (outSz >= OUTPUT_BLOCK_LEN) {
                    XMEMCPY(out, digest, OUTPUT_BLOCK_LEN);
                    outSz -= OUTPUT_BLOCK_LEN;
                    out += OUTPUT_BLOCK_LEN;
                    array_add_one(data, DRBG_SEED_LEN);
                }
                else {
                    XMEMCPY(out, digest, outSz);
                    outSz = 0;
                }
            }
        }
        else {
            /* wc_Sha256Update or wc_Sha256Final returned error */
            break;
        }
    }
    ForceZero(data, sizeof(data));

#ifdef WC_ASYNC_ENABLE_SHA256
    WC_FREE_VAR(digest, drbg->heap);
#endif

    return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

static WC_INLINE void array_add(byte* d, word32 dLen, const byte* s, word32 sLen)
{
    word16 carry = 0;

    if (dLen > 0 && sLen > 0 && dLen >= sLen) {
        int sIdx, dIdx;

        dIdx = dLen - 1;
        for (sIdx = sLen - 1; sIdx >= 0; sIdx--) {
            carry += (word16)d[dIdx] + (word16)s[sIdx];
            d[dIdx] = (byte)carry;
            carry >>= 8;
            dIdx--;
        }

        for (; dIdx >= 0; dIdx--) {
            carry += (word16)d[dIdx];
            d[dIdx] = (byte)carry;
            carry >>= 8;
        }
    }
}

/* Returns: DRBG_SUCCESS, DRBG_NEED_RESEED, or DRBG_FAILURE */
static int Hash_DRBG_Generate(DRBG_internal* drbg, byte* out, word32 outSz)
{
    int ret;
#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha256* sha = &drbg->sha256;
#else
    wc_Sha256 sha[1];
#endif
    byte type;
    word32 reseedCtr;

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

    if (drbg->reseedCtr == RESEED_INTERVAL) {
        return DRBG_NEED_RESEED;
    } else {
    #ifdef WC_ASYNC_ENABLE_SHA256
        WC_DECLARE_VAR(digest, byte, WC_SHA256_DIGEST_SIZE, drbg->heap);
        if (digest == NULL)
            return MEMORY_E;
    #else
        byte digest[WC_SHA256_DIGEST_SIZE];
    #endif
        type = drbgGenerateH;
        reseedCtr = drbg->reseedCtr;

        ret = Hash_gen(drbg, out, outSz, drbg->V);
        if (ret == DRBG_SUCCESS) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
        #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
            ret = wc_InitSha256_ex(sha, drbg->heap, drbg->devId);
        #else
            ret = wc_InitSha256(sha);
        #endif
            if (ret == 0)
#endif
                ret = wc_Sha256Update(sha, &type, sizeof(type));
            if (ret == 0)
                ret = wc_Sha256Update(sha, drbg->V, sizeof(drbg->V));
            if (ret == 0)
                ret = wc_Sha256Final(sha, digest);

#ifndef WOLFSSL_SMALL_STACK_CACHE
            wc_Sha256Free(sha);
#endif

            if (ret == 0) {
                array_add(drbg->V, sizeof(drbg->V), digest, WC_SHA256_DIGEST_SIZE);
                array_add(drbg->V, sizeof(drbg->V), drbg->C, sizeof(drbg->C));
            #ifdef LITTLE_ENDIAN_ORDER
                reseedCtr = ByteReverseWord32(reseedCtr);
            #endif
                array_add(drbg->V, sizeof(drbg->V),
                                          (byte*)&reseedCtr, sizeof(reseedCtr));
                ret = DRBG_SUCCESS;
            }
            drbg->reseedCtr++;
        }
        ForceZero(digest, WC_SHA256_DIGEST_SIZE);
    #ifdef WC_ASYNC_ENABLE_SHA256
        WC_FREE_VAR(digest, drbg->heap);
    #endif
    }

    return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static int Hash_DRBG_Instantiate(DRBG_internal* drbg, const byte* seed, word32 seedSz,
                                             const byte* nonce, word32 nonceSz,
                                             void* heap, int devId)
{
    int ret = DRBG_FAILURE;

    XMEMSET(drbg, 0, sizeof(DRBG_internal));
#if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
    drbg->heap = heap;
    drbg->devId = devId;
#else
    (void)heap;
    (void)devId;
#endif

#ifdef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha256_ex(&drbg->sha256, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha256(&drbg->sha256);
    #endif
    if (ret != 0)
        return ret;
#endif

    if (Hash_df(drbg, drbg->V, sizeof(drbg->V), drbgInitV, seed, seedSz,
                                              nonce, nonceSz) == DRBG_SUCCESS &&
        Hash_df(drbg, drbg->C, sizeof(drbg->C), drbgInitC, drbg->V,
                                    sizeof(drbg->V), NULL, 0) == DRBG_SUCCESS) {

        drbg->reseedCtr = 1;
        drbg->lastBlock = 0;
        drbg->matchCount = 0;
        ret = DRBG_SUCCESS;
    }

    return ret;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static int Hash_DRBG_Uninstantiate(DRBG_internal* drbg)
{
    word32 i;
    int    compareSum = 0;
    byte*  compareDrbg = (byte*)drbg;

#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha256Free(&drbg->sha256);
#endif

    ForceZero(drbg, sizeof(DRBG_internal));

    for (i = 0; i < sizeof(DRBG_internal); i++)
        compareSum |= compareDrbg[i] ^ 0;

    return (compareSum == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}


int wc_RNG_TestSeed(const byte* seed, word32 seedSz)
{
    int ret = 0;

    /* Check the seed for duplicate words. */
    word32 seedIdx = 0;
    word32 scratchSz = min(SEED_BLOCK_SZ, seedSz - SEED_BLOCK_SZ);

    while (seedIdx < seedSz - SEED_BLOCK_SZ) {
        if (ConstantCompare(seed + seedIdx,
                            seed + seedIdx + scratchSz,
                            scratchSz) == 0) {

            ret = DRBG_CONT_FAILURE;
        }
        seedIdx += SEED_BLOCK_SZ;
        scratchSz = min(SEED_BLOCK_SZ, (seedSz - seedIdx));
    }

    return ret;
}
#endif /* HAVE_HASHDRBG */
/* End NIST DRBG Code */


static int _InitRng(WC_RNG* rng, byte* nonce, word32 nonceSz,
                    void* heap, int devId)
{
    int ret = 0;
#ifdef HAVE_HASHDRBG
    word32 seedSz = SEED_SZ + SEED_BLOCK_SZ;
#endif

    (void)nonce;
    (void)nonceSz;

    if (rng == NULL)
        return BAD_FUNC_ARG;
    if (nonce == NULL && nonceSz != 0)
        return BAD_FUNC_ARG;

#ifdef WOLFSSL_HEAP_TEST
    rng->heap = (void*)WOLFSSL_HEAP_TEST;
    (void)heap;
#else
    rng->heap = heap;
#endif
#if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
    rng->devId = devId;
    #if defined(WOLF_CRYPTO_CB)
        rng->seed.devId = devId;
    #endif
#else
    (void)devId;
#endif

#ifdef HAVE_HASHDRBG
    /* init the DBRG to known values */
    rng->drbg = NULL;
    rng->status = DRBG_NOT_INIT;
#endif

#if defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND) || \
    defined(HAVE_AMD_RDSEED)
    /* init the intel RD seed and/or rand */
    wc_InitRng_IntelRD();
#endif

    /* configure async RNG source if available */
#ifdef WOLFSSL_ASYNC_CRYPT
    ret = wolfAsync_DevCtxInit(&rng->asyncDev, WOLFSSL_ASYNC_MARKER_RNG,
                                                        rng->heap, rng->devId);
    if (ret != 0)
        return ret;
#endif

#ifdef HAVE_INTEL_RDRAND
    /* if CPU supports RDRAND, use it directly and by-pass DRBG init */
    if (IS_INTEL_RDRAND(intel_flags))
        return 0;
#endif

#ifdef WOLFSSL_XILINX_CRYPT_VERSAL
    ret = wc_VersalTrngInit(nonce, nonceSz);
    if (ret)
        return ret;
#endif

#ifdef CUSTOM_RAND_GENERATE_BLOCK
    ret = 0; /* success */
#else
#ifdef HAVE_HASHDRBG
    if (nonceSz == 0)
        seedSz = MAX_SEED_SZ;

    if (wc_RNG_HealthTestLocal(0) == 0) {
    #ifdef WC_ASYNC_ENABLE_SHA256
        WC_DECLARE_VAR(seed, byte, MAX_SEED_SZ, rng->heap);
        if (seed == NULL)
            return MEMORY_E;
    #else
        byte seed[MAX_SEED_SZ];
    #endif

#if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
        rng->drbg =
                (struct DRBG*)XMALLOC(sizeof(DRBG_internal), rng->heap,
                                                          DYNAMIC_TYPE_RNG);
        if (rng->drbg == NULL) {
            ret = MEMORY_E;
            rng->status = DRBG_FAILED;
        }
#else
        rng->drbg = (struct DRBG*)&rng->drbg_data;
#endif
        if (ret == 0) {
#ifdef WC_RNG_SEED_CB
            if (seedCb == NULL) {
                ret = DRBG_NO_SEED_CB;
            }
            else {
                ret = seedCb(&rng->seed, seed, seedSz);
                if (ret != 0) {
                    ret = DRBG_FAILURE;
                }
            }
#else
            ret = wc_GenerateSeed(&rng->seed, seed, seedSz);
#endif
            if (ret == 0)
                ret = wc_RNG_TestSeed(seed, seedSz);
            else {
                ret = DRBG_FAILURE;
                rng->status = DRBG_FAILED;
            }

            if (ret == DRBG_SUCCESS)
                ret = Hash_DRBG_Instantiate((DRBG_internal *)rng->drbg,
                            seed + SEED_BLOCK_SZ, seedSz - SEED_BLOCK_SZ,
                            nonce, nonceSz, rng->heap, devId);

            if (ret != DRBG_SUCCESS) {
            #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
                XFREE(rng->drbg, rng->heap, DYNAMIC_TYPE_RNG);
            #endif
                rng->drbg = NULL;
            }
        }

        ForceZero(seed, seedSz);
    #ifdef WC_ASYNC_ENABLE_SHA256
        WC_FREE_VAR(seed, rng->heap);
    #endif
    }
    else
        ret = DRBG_CONT_FAILURE;

    if (ret == DRBG_SUCCESS) {
#ifdef WOLFSSL_CHECK_MEM_ZERO
#ifdef HAVE_HASHDRBG
        struct DRBG_internal* drbg = (struct DRBG_internal*)rng->drbg;
        wc_MemZero_Add("DRBG V", &drbg->V, sizeof(drbg->V));
        wc_MemZero_Add("DRBG C", &drbg->C, sizeof(drbg->C));
#endif
#endif

        rng->status = DRBG_OK;
        ret = 0;
    }
    else if (ret == DRBG_CONT_FAILURE) {
        rng->status = DRBG_CONT_FAILED;
        ret = DRBG_CONT_FIPS_E;
    }
    else if (ret == DRBG_FAILURE) {
        rng->status = DRBG_FAILED;
        ret = RNG_FAILURE_E;
    }
    else {
        rng->status = DRBG_FAILED;
    }
#endif /* HAVE_HASHDRBG */
#endif /* CUSTOM_RAND_GENERATE_BLOCK */

    return ret;
}


WOLFSSL_ABI
WC_RNG* wc_rng_new(byte* nonce, word32 nonceSz, void* heap)
{
    WC_RNG* rng;

    rng = (WC_RNG*)XMALLOC(sizeof(WC_RNG), heap, DYNAMIC_TYPE_RNG);
    if (rng) {
        int error = _InitRng(rng, nonce, nonceSz, heap, INVALID_DEVID) != 0;
        if (error) {
            XFREE(rng, heap, DYNAMIC_TYPE_RNG);
            rng = NULL;
        }
    }

    return rng;
}


WOLFSSL_ABI
void wc_rng_free(WC_RNG* rng)
{
    if (rng) {
        void* heap = rng->heap;

        wc_FreeRng(rng);
        ForceZero(rng, sizeof(WC_RNG));
        XFREE(rng, heap, DYNAMIC_TYPE_RNG);
        (void)heap;
    }
}

WOLFSSL_ABI
int wc_InitRng(WC_RNG* rng)
{
    return _InitRng(rng, NULL, 0, NULL, INVALID_DEVID);
}


int wc_InitRng_ex(WC_RNG* rng, void* heap, int devId)
{
    return _InitRng(rng, NULL, 0, heap, devId);
}


int wc_InitRngNonce(WC_RNG* rng, byte* nonce, word32 nonceSz)
{
    return _InitRng(rng, nonce, nonceSz, NULL, INVALID_DEVID);
}


int wc_InitRngNonce_ex(WC_RNG* rng, byte* nonce, word32 nonceSz,
                       void* heap, int devId)
{
    return _InitRng(rng, nonce, nonceSz, heap, devId);
}


/* place a generated block in output */
WOLFSSL_ABI
int wc_RNG_GenerateBlock(WC_RNG* rng, byte* output, word32 sz)
{
    int ret;

    if (rng == NULL || output == NULL)
        return BAD_FUNC_ARG;

    if (sz == 0)
        return 0;

#ifdef WOLF_CRYPTO_CB
    if (rng->devId != INVALID_DEVID) {
        ret = wc_CryptoCb_RandomBlock(rng, output, sz);
        if (ret != CRYPTOCB_UNAVAILABLE)
            return ret;
        /* fall-through when unavailable */
    }
#endif

#ifdef HAVE_INTEL_RDRAND
    if (IS_INTEL_RDRAND(intel_flags))
        return wc_GenerateRand_IntelRD(NULL, output, sz);
#endif

#if defined(WOLFSSL_SILABS_SE_ACCEL) && defined(WOLFSSL_SILABS_TRNG)
    return silabs_GenerateRand(output, sz);
#endif

#if defined(WOLFSSL_ASYNC_CRYPT)
    if (rng->asyncDev.marker == WOLFSSL_ASYNC_MARKER_RNG) {
        /* these are blocking */
    #ifdef HAVE_CAVIUM
        return NitroxRngGenerateBlock(rng, output, sz);
    #elif defined(HAVE_INTEL_QA) && defined(QAT_ENABLE_RNG)
        return IntelQaDrbg(&rng->asyncDev, output, sz);
    #else
        /* simulator not supported */
    #endif
    }
#endif

#ifdef CUSTOM_RAND_GENERATE_BLOCK
    XMEMSET(output, 0, sz);
    ret = CUSTOM_RAND_GENERATE_BLOCK(output, sz);
#else

#ifdef HAVE_HASHDRBG
    if (sz > RNG_MAX_BLOCK_LEN)
        return BAD_FUNC_ARG;

    if (rng->status != DRBG_OK)
        return RNG_FAILURE_E;

    ret = Hash_DRBG_Generate((DRBG_internal *)rng->drbg, output, sz);
    if (ret == DRBG_NEED_RESEED) {
        if (wc_RNG_HealthTestLocal(1) == 0) {
            byte newSeed[SEED_SZ + SEED_BLOCK_SZ];

            ret = wc_GenerateSeed(&rng->seed, newSeed,
                                  SEED_SZ + SEED_BLOCK_SZ);
            if (ret != 0)
                ret = DRBG_FAILURE;
            else
                ret = wc_RNG_TestSeed(newSeed, SEED_SZ + SEED_BLOCK_SZ);

            if (ret == DRBG_SUCCESS)
                ret = Hash_DRBG_Reseed((DRBG_internal *)rng->drbg,
                                       newSeed + SEED_BLOCK_SZ, SEED_SZ);
            if (ret == DRBG_SUCCESS)
                ret = Hash_DRBG_Generate((DRBG_internal *)rng->drbg, output, sz);

            ForceZero(newSeed, sizeof(newSeed));
        }
        else
            ret = DRBG_CONT_FAILURE;
    }

    if (ret == DRBG_SUCCESS) {
        ret = 0;
    }
    else if (ret == DRBG_CONT_FAILURE) {
        ret = DRBG_CONT_FIPS_E;
        rng->status = DRBG_CONT_FAILED;
    }
    else {
        ret = RNG_FAILURE_E;
        rng->status = DRBG_FAILED;
    }
#else

    /* if we get here then there is an RNG configuration error */
    ret = RNG_FAILURE_E;

#endif /* HAVE_HASHDRBG */
#endif /* CUSTOM_RAND_GENERATE_BLOCK */

    return ret;
}


int wc_RNG_GenerateByte(WC_RNG* rng, byte* b)
{
    return wc_RNG_GenerateBlock(rng, b, 1);
}


int wc_FreeRng(WC_RNG* rng)
{
    int ret = 0;

    if (rng == NULL)
        return BAD_FUNC_ARG;

#if defined(WOLFSSL_ASYNC_CRYPT)
    wolfAsync_DevCtxFree(&rng->asyncDev, WOLFSSL_ASYNC_MARKER_RNG);
#endif

#ifdef HAVE_HASHDRBG
    if (rng->drbg != NULL) {
      if (Hash_DRBG_Uninstantiate((DRBG_internal *)rng->drbg) != DRBG_SUCCESS)
            ret = RNG_FAILURE_E;

    #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
        XFREE(rng->drbg, rng->heap, DYNAMIC_TYPE_RNG);
    #elif defined(WOLFSSL_CHECK_MEM_ZERO)
        wc_MemZero_Check(rng->drbg, sizeof(DRBG_internal));
    #endif
        rng->drbg = NULL;
    }

    rng->status = DRBG_NOT_INIT;
#endif /* HAVE_HASHDRBG */

#ifdef WOLFSSL_XILINX_CRYPT_VERSAL\
    /* don't overwrite previously set error */
    if (wc_VersalTrngReset() && !ret)
        ret = WC_HW_E;
#endif

    return ret;
}

#ifdef HAVE_HASHDRBG
int wc_RNG_HealthTest(int reseed, const byte* seedA, word32 seedASz,
                                  const byte* seedB, word32 seedBSz,
                                  byte* output, word32 outputSz)
{
    return wc_RNG_HealthTest_ex(reseed, NULL, 0,
                                seedA, seedASz, seedB, seedBSz,
                                output, outputSz,
                                NULL, INVALID_DEVID);
}


int wc_RNG_HealthTest_ex(int reseed, const byte* nonce, word32 nonceSz,
                                  const byte* seedA, word32 seedASz,
                                  const byte* seedB, word32 seedBSz,
                                  byte* output, word32 outputSz,
                                  void* heap, int devId)
{
    int ret = -1;
    DRBG_internal* drbg;
#ifndef WOLFSSL_SMALL_STACK
    DRBG_internal  drbg_var;
#endif

    if (seedA == NULL || output == NULL) {
        return BAD_FUNC_ARG;
    }

    if (reseed != 0 && seedB == NULL) {
        return BAD_FUNC_ARG;
    }

    if (outputSz != RNG_HEALTH_TEST_CHECK_SIZE) {
        return ret;
    }

#ifdef WOLFSSL_SMALL_STACK
    drbg = (DRBG_internal*)XMALLOC(sizeof(DRBG_internal), NULL, DYNAMIC_TYPE_RNG);
    if (drbg == NULL) {
        return MEMORY_E;
    }
#else
    drbg = &drbg_var;
#endif

    if (Hash_DRBG_Instantiate(drbg, seedA, seedASz, nonce, nonceSz,
                              heap, devId) != 0) {
        goto exit_rng_ht;
    }

    if (reseed) {
        if (Hash_DRBG_Reseed(drbg, seedB, seedBSz) != 0) {
            goto exit_rng_ht;
        }
    }

    /* This call to generate is prescribed by the NIST DRBGVS
     * procedure. The results are thrown away. The known
     * answer test checks the second block of DRBG out of
     * the generator to ensure the internal state is updated
     * as expected. */
    if (Hash_DRBG_Generate(drbg, output, outputSz) != 0) {
        goto exit_rng_ht;
    }

    if (Hash_DRBG_Generate(drbg, output, outputSz) != 0) {
        goto exit_rng_ht;
    }

    /* Mark success */
    ret = 0;

exit_rng_ht:

    /* This is safe to call even if Hash_DRBG_Instantiate fails */
    if (Hash_DRBG_Uninstantiate(drbg) != 0) {
        ret = -1;
    }

#ifdef WOLFSSL_SMALL_STACK
    XFREE(drbg, NULL, DYNAMIC_TYPE_RNG);
#endif

    return ret;
}


const FLASH_QUALIFIER byte seedA_data[] = {
    0x63, 0x36, 0x33, 0x77, 0xe4, 0x1e, 0x86, 0x46, 0x8d, 0xeb, 0x0a, 0xb4,
    0xa8, 0xed, 0x68, 0x3f, 0x6a, 0x13, 0x4e, 0x47, 0xe0, 0x14, 0xc7, 0x00,
    0x45, 0x4e, 0x81, 0xe9, 0x53, 0x58, 0xa5, 0x69, 0x80, 0x8a, 0xa3, 0x8f,
    0x2a, 0x72, 0xa6, 0x23, 0x59, 0x91, 0x5a, 0x9f, 0x8a, 0x04, 0xca, 0x68
};

const FLASH_QUALIFIER byte reseedSeedA_data[] = {
    0xe6, 0x2b, 0x8a, 0x8e, 0xe8, 0xf1, 0x41, 0xb6, 0x98, 0x05, 0x66, 0xe3,
    0xbf, 0xe3, 0xc0, 0x49, 0x03, 0xda, 0xd4, 0xac, 0x2c, 0xdf, 0x9f, 0x22,
    0x80, 0x01, 0x0a, 0x67, 0x39, 0xbc, 0x83, 0xd3
};

const FLASH_QUALIFIER byte outputA_data[] = {
    0x04, 0xee, 0xc6, 0x3b, 0xb2, 0x31, 0xdf, 0x2c, 0x63, 0x0a, 0x1a, 0xfb,
    0xe7, 0x24, 0x94, 0x9d, 0x00, 0x5a, 0x58, 0x78, 0x51, 0xe1, 0xaa, 0x79,
    0x5e, 0x47, 0x73, 0x47, 0xc8, 0xb0, 0x56, 0x62, 0x1c, 0x18, 0xbd, 0xdc,
    0xdd, 0x8d, 0x99, 0xfc, 0x5f, 0xc2, 0xb9, 0x20, 0x53, 0xd8, 0xcf, 0xac,
    0xfb, 0x0b, 0xb8, 0x83, 0x12, 0x05, 0xfa, 0xd1, 0xdd, 0xd6, 0xc0, 0x71,
    0x31, 0x8a, 0x60, 0x18, 0xf0, 0x3b, 0x73, 0xf5, 0xed, 0xe4, 0xd4, 0xd0,
    0x71, 0xf9, 0xde, 0x03, 0xfd, 0x7a, 0xea, 0x10, 0x5d, 0x92, 0x99, 0xb8,
    0xaf, 0x99, 0xaa, 0x07, 0x5b, 0xdb, 0x4d, 0xb9, 0xaa, 0x28, 0xc1, 0x8d,
    0x17, 0x4b, 0x56, 0xee, 0x2a, 0x01, 0x4d, 0x09, 0x88, 0x96, 0xff, 0x22,
    0x82, 0xc9, 0x55, 0xa8, 0x19, 0x69, 0xe0, 0x69, 0xfa, 0x8c, 0xe0, 0x07,
    0xa1, 0x80, 0x18, 0x3a, 0x07, 0xdf, 0xae, 0x17
};

const FLASH_QUALIFIER byte seedB_data[] = {
    0xa6, 0x5a, 0xd0, 0xf3, 0x45, 0xdb, 0x4e, 0x0e, 0xff, 0xe8, 0x75, 0xc3,
    0xa2, 0xe7, 0x1f, 0x42, 0xc7, 0x12, 0x9d, 0x62, 0x0f, 0xf5, 0xc1, 0x19,
    0xa9, 0xef, 0x55, 0xf0, 0x51, 0x85, 0xe0, 0xfb, /* nonce next */
    0x85, 0x81, 0xf9, 0x31, 0x75, 0x17, 0x27, 0x6e, 0x06, 0xe9, 0x60, 0x7d,
    0xdb, 0xcb, 0xcc, 0x2e
};

const FLASH_QUALIFIER byte outputB_data[] = {
    0xd3, 0xe1, 0x60, 0xc3, 0x5b, 0x99, 0xf3, 0x40, 0xb2, 0x62, 0x82, 0x64,
    0xd1, 0x75, 0x10, 0x60, 0xe0, 0x04, 0x5d, 0xa3, 0x83, 0xff, 0x57, 0xa5,
    0x7d, 0x73, 0xa6, 0x73, 0xd2, 0xb8, 0xd8, 0x0d, 0xaa, 0xf6, 0xa6, 0xc3,
    0x5a, 0x91, 0xbb, 0x45, 0x79, 0xd7, 0x3f, 0xd0, 0xc8, 0xfe, 0xd1, 0x11,
    0xb0, 0x39, 0x13, 0x06, 0x82, 0x8a, 0xdf, 0xed, 0x52, 0x8f, 0x01, 0x81,
    0x21, 0xb3, 0xfe, 0xbd, 0xc3, 0x43, 0xe7, 0x97, 0xb8, 0x7d, 0xbb, 0x63,
    0xdb, 0x13, 0x33, 0xde, 0xd9, 0xd1, 0xec, 0xe1, 0x77, 0xcf, 0xa6, 0xb7,
    0x1f, 0xe8, 0xab, 0x1d, 0xa4, 0x66, 0x24, 0xed, 0x64, 0x15, 0xe5, 0x1c,
    0xcd, 0xe2, 0xc7, 0xca, 0x86, 0xe2, 0x83, 0x99, 0x0e, 0xea, 0xeb, 0x91,
    0x12, 0x04, 0x15, 0x52, 0x8b, 0x22, 0x95, 0x91, 0x02, 0x81, 0xb0, 0x2d,
    0xd4, 0x31, 0xf4, 0xc9, 0xf7, 0x04, 0x27, 0xdf
};


static int wc_RNG_HealthTestLocal(int reseed)
{
    int ret = 0;
#ifdef WOLFSSL_SMALL_STACK
    byte* check;
#else
    byte  check[RNG_HEALTH_TEST_CHECK_SIZE];
#endif

#ifdef WOLFSSL_SMALL_STACK
    check = (byte*)XMALLOC(RNG_HEALTH_TEST_CHECK_SIZE, NULL,
                           DYNAMIC_TYPE_TMP_BUFFER);
    if (check == NULL) {
        return MEMORY_E;
    }
#endif

    if (reseed) {
#ifdef WOLFSSL_USE_FLASHMEM
        byte* seedA = (byte*)XMALLOC(sizeof(seedA_data), NULL,
                             DYNAMIC_TYPE_TMP_BUFFER);
        byte* reseedSeedA = (byte*)XMALLOC(sizeof(reseedSeedA_data), NULL,
                             DYNAMIC_TYPE_TMP_BUFFER);
        byte* outputA = (byte*)XMALLOC(sizeof(outputA_data), NULL,
                             DYNAMIC_TYPE_TMP_BUFFER);

        if (!seedA || !reseedSeedA || !outputA) {
            XFREE(seedA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(reseedSeedA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            ret = MEMORY_E;
        }
        else {
            XMEMCPY_P(seedA, seedA_data, sizeof(seedA_data));
            XMEMCPY_P(reseedSeedA, reseedSeedA_data, sizeof(reseedSeedA_data));
            XMEMCPY_P(outputA, outputA_data, sizeof(outputA_data));
#else
        const byte* seedA = seedA_data;
        const byte* reseedSeedA = reseedSeedA_data;
        const byte* outputA = outputA_data;
#endif
        ret = wc_RNG_HealthTest(1, seedA, sizeof(seedA_data),
                                reseedSeedA, sizeof(reseedSeedA_data),
                                check, RNG_HEALTH_TEST_CHECK_SIZE);
        if (ret == 0) {
            if (ConstantCompare(check, outputA,
                                RNG_HEALTH_TEST_CHECK_SIZE) != 0)
                ret = -1;
        }

#ifdef WOLFSSL_USE_FLASHMEM
            XFREE(seedA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(reseedSeedA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
        }
#endif
    }
    else {
#ifdef WOLFSSL_USE_FLASHMEM
        byte* seedB = (byte*)XMALLOC(sizeof(seedB_data), NULL,
                             DYNAMIC_TYPE_TMP_BUFFER);
        byte* outputB = (byte*)XMALLOC(sizeof(outputB_data), NULL,
                               DYNAMIC_TYPE_TMP_BUFFER);

        if (!seedB || !outputB) {
            XFREE(seedB, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputB, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            ret = MEMORY_E;
        }
        else {
            XMEMCPY_P(seedB, seedB_data, sizeof(seedB_data));
            XMEMCPY_P(outputB, outputB_data, sizeof(outputB_data));
#else
        const byte* seedB = seedB_data;
        const byte* outputB = outputB_data;
#endif
        ret = wc_RNG_HealthTest(0, seedB, sizeof(seedB_data),
                                NULL, 0,
                                check, RNG_HEALTH_TEST_CHECK_SIZE);
        if (ret == 0) {
            if (ConstantCompare(check, outputB,
                                RNG_HEALTH_TEST_CHECK_SIZE) != 0)
                ret = -1;
        }

        /* The previous test cases use a large seed instead of a seed and nonce.
         * seedB is actually from a test case with a seed and nonce, and
         * just concatenates them. The pivot point between seed and nonce is
         * byte 32, feed them into the health test separately. */
        if (ret == 0) {
            ret = wc_RNG_HealthTest_ex(0,
                                    seedB + 32, sizeof(seedB_data) - 32,
                                    seedB, 32,
                                    NULL, 0,
                                    check, RNG_HEALTH_TEST_CHECK_SIZE,
                                    NULL, INVALID_DEVID);
            if (ret == 0) {
                if (ConstantCompare(check, outputB, sizeof(outputB_data)) != 0)
                    ret = -1;
            }
        }

#ifdef WOLFSSL_USE_FLASHMEM
            XFREE(seedB, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputB, NULL, DYNAMIC_TYPE_TMP_BUFFER);
        }
#endif
    }

#ifdef WOLFSSL_SMALL_STACK
    XFREE(check, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif

    return ret;
}

#endif /* HAVE_HASHDRBG */


#ifdef HAVE_WNR

/*
 * Init global Whitewood netRandom context
 * Returns 0 on success, negative on error
 */
int wc_InitNetRandom(const char* configFile, wnr_hmac_key hmac_cb, int timeout)
{
    if (configFile == NULL || timeout < 0)
        return BAD_FUNC_ARG;

    if (wnr_mutex_init > 0) {
        WOLFSSL_MSG("netRandom context already created, skipping");
        return 0;
    }

    if (wc_InitMutex(&wnr_mutex) != 0) {
        WOLFSSL_MSG("Bad Init Mutex wnr_mutex");
        return BAD_MUTEX_E;
    }
    wnr_mutex_init = 1;

    if (wc_LockMutex(&wnr_mutex) != 0) {
        WOLFSSL_MSG("Bad Lock Mutex wnr_mutex");
        return BAD_MUTEX_E;
    }

    /* store entropy timeout */
    wnr_timeout = timeout;

    /* create global wnr_context struct */
    if (wnr_create(&wnr_ctx) != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error creating global netRandom context");
        return RNG_FAILURE_E;
    }

    /* load config file */
    if (wnr_config_loadf(wnr_ctx, (char*)configFile) != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error loading config file into netRandom context");
        wnr_destroy(wnr_ctx);
        wnr_ctx = NULL;
        return RNG_FAILURE_E;
    }

    /* create/init polling mechanism */
    if (wnr_poll_create() != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error initializing netRandom polling mechanism");
        wnr_destroy(wnr_ctx);
        wnr_ctx = NULL;
        return RNG_FAILURE_E;
    }

    /* validate config, set HMAC callback (optional) */
    if (wnr_setup(wnr_ctx, hmac_cb) != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error setting up netRandom context");
        wnr_destroy(wnr_ctx);
        wnr_ctx = NULL;
        wnr_poll_destroy();
        return RNG_FAILURE_E;
    }

    wc_UnLockMutex(&wnr_mutex);

    return 0;
}

/*
 * Free global Whitewood netRandom context
 * Returns 0 on success, negative on error
 */
int wc_FreeNetRandom(void)
{
    if (wnr_mutex_init > 0) {

        if (wc_LockMutex(&wnr_mutex) != 0) {
            WOLFSSL_MSG("Bad Lock Mutex wnr_mutex");
            return BAD_MUTEX_E;
        }

        if (wnr_ctx != NULL) {
            wnr_destroy(wnr_ctx);
            wnr_ctx = NULL;
        }
        wnr_poll_destroy();

        wc_UnLockMutex(&wnr_mutex);

        wc_FreeMutex(&wnr_mutex);
        wnr_mutex_init = 0;
    }

    return 0;
}

#endif /* HAVE_WNR */


#if defined(HAVE_INTEL_RDRAND) || defined(HAVE_INTEL_RDSEED) || \
    defined(HAVE_AMD_RDSEED)

#ifdef WOLFSSL_ASYNC_CRYPT
    /* need more retries if multiple cores */
    #define INTELRD_RETRY (32 * 8)
#else
    #define INTELRD_RETRY 32
#endif

#if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)

#ifndef USE_INTEL_INTRINSICS

    /* return 0 on success */
    static WC_INLINE int IntelRDseed64(word64* seed)
    {
        unsigned char ok;

        __asm__ volatile("rdseed %0; setc %1":"=r"(*seed), "=qm"(ok));
        return (ok) ? 0 : -1;
    }

#else /* USE_INTEL_INTRINSICS */
    /* The compiler Visual Studio uses does not allow inline assembly.
     * It does allow for Intel intrinsic functions. */

    /* return 0 on success */
# ifdef __GNUC__
    __attribute__((target("rdseed")))
# endif
    static WC_INLINE int IntelRDseed64(word64* seed)
    {
        int ok;

        ok = _rdseed64_step((unsigned long long*) seed);
        return (ok) ? 0 : -1;
    }

#endif /* USE_INTEL_INTRINSICS */

/* return 0 on success */
static WC_INLINE int IntelRDseed64_r(word64* rnd)
{
    int i;
    for (i = 0; i < INTELRD_RETRY; i++) {
        if (IntelRDseed64(rnd) == 0)
            return 0;
    }
    return -1;
}

#ifndef WOLFSSL_LINUXKM
/* return 0 on success */
static int wc_GenerateSeed_IntelRD(OS_Seed* os, byte* output, word32 sz)
{
    int ret;
    word64 rndTmp;

    (void)os;

    if (!IS_INTEL_RDSEED(intel_flags))
        return -1;

    for (; (sz / sizeof(word64)) > 0; sz -= sizeof(word64),
                                                    output += sizeof(word64)) {
        ret = IntelRDseed64_r((word64*)output);
        if (ret != 0)
            return ret;
    }
    if (sz == 0)
        return 0;

    /* handle unaligned remainder */
    ret = IntelRDseed64_r(&rndTmp);
    if (ret != 0)
        return ret;

    XMEMCPY(output, &rndTmp, sz);
    ForceZero(&rndTmp, sizeof(rndTmp));

    return 0;
}
#endif

#endif /* HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */

#ifdef HAVE_INTEL_RDRAND

#ifndef USE_INTEL_INTRINSICS

/* return 0 on success */
static WC_INLINE int IntelRDrand64(word64 *rnd)
{
    unsigned char ok;

    __asm__ volatile("rdrand %0; setc %1":"=r"(*rnd), "=qm"(ok));

    return (ok) ? 0 : -1;
}

#else /* USE_INTEL_INTRINSICS */
    /* The compiler Visual Studio uses does not allow inline assembly.
     * It does allow for Intel intrinsic functions. */

/* return 0 on success */
# ifdef __GNUC__
__attribute__((target("rdrnd")))
# endif
static WC_INLINE int IntelRDrand64(word64 *rnd)
{
    int ok;

    ok = _rdrand64_step((unsigned long long*) rnd);

    return (ok) ? 0 : -1;
}

#endif /* USE_INTEL_INTRINSICS */

/* return 0 on success */
static WC_INLINE int IntelRDrand64_r(word64 *rnd)
{
    int i;
    for (i = 0; i < INTELRD_RETRY; i++) {
        if (IntelRDrand64(rnd) == 0)
            return 0;
    }
    return -1;
}

/* return 0 on success */
static int wc_GenerateRand_IntelRD(OS_Seed* os, byte* output, word32 sz)
{
    int ret;
    word64 rndTmp;

    (void)os;

    if (!IS_INTEL_RDRAND(intel_flags))
        return -1;

    for (; (sz / sizeof(word64)) > 0; sz -= sizeof(word64),
                                                    output += sizeof(word64)) {
        ret = IntelRDrand64_r((word64 *)output);
        if (ret != 0)
            return ret;
    }
    if (sz == 0)
        return 0;

    /* handle unaligned remainder */
    ret = IntelRDrand64_r(&rndTmp);
    if (ret != 0)
        return ret;

    XMEMCPY(output, &rndTmp, sz);

    return 0;
}

#endif /* HAVE_INTEL_RDRAND */
#endif /* HAVE_INTEL_RDRAND || HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */


/* Begin wc_GenerateSeed Implementations */
#if defined(CUSTOM_RAND_GENERATE_SEED)

    /* Implement your own random generation function
     * Return 0 to indicate success
     * int rand_gen_seed(byte* output, word32 sz);
     * #define CUSTOM_RAND_GENERATE_SEED  rand_gen_seed */

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os; /* Suppress unused arg warning */
        return CUSTOM_RAND_GENERATE_SEED(output, sz);
    }

#elif defined(CUSTOM_RAND_GENERATE_SEED_OS)

    /* Implement your own random generation function,
     *  which includes OS_Seed.
     * Return 0 to indicate success
     * int rand_gen_seed(OS_Seed* os, byte* output, word32 sz);
     * #define CUSTOM_RAND_GENERATE_SEED_OS  rand_gen_seed */

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        return CUSTOM_RAND_GENERATE_SEED_OS(os, output, sz);
    }

#elif defined(CUSTOM_RAND_GENERATE)

   /* Implement your own random generation function
    * word32 rand_gen(void);
    * #define CUSTOM_RAND_GENERATE  rand_gen  */

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i = 0;

        (void)os;

        while (i < sz)
        {
            /* If not aligned or there is odd/remainder */
            if( (i + sizeof(CUSTOM_RAND_TYPE)) > sz ||
                ((wc_ptr_t)&output[i] % sizeof(CUSTOM_RAND_TYPE)) != 0
            ) {
                /* Single byte at a time */
                output[i++] = (byte)CUSTOM_RAND_GENERATE();
            }
            else {
                /* Use native 8, 16, 32 or 64 copy instruction */
                *((CUSTOM_RAND_TYPE*)&output[i]) = CUSTOM_RAND_GENERATE();
                i += sizeof(CUSTOM_RAND_TYPE);
            }
        }

        return 0;
    }

#elif defined(WOLFSSL_SGX)

int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
    int ret = !SGX_SUCCESS;
    int i, read_max = 10;

    for (i = 0; i < read_max && ret != SGX_SUCCESS; i++) {
        ret = sgx_read_rand(output, sz);
    }

    (void)os;
    return (ret == SGX_SUCCESS) ? 0 : 1;
}

#elif defined(USE_WINDOWS_API)

int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
#ifdef WOLF_CRYPTO_CB
    int ret;

    if (os != NULL && os->devId != INVALID_DEVID) {
        ret = wc_CryptoCb_RandomSeed(os, output, sz);
        if (ret != CRYPTOCB_UNAVAILABLE)
            return ret;
        /* fall-through when unavailable */
    }
#endif

    #ifdef HAVE_INTEL_RDSEED
        if (IS_INTEL_RDSEED(intel_flags)) {
             if (!wc_GenerateSeed_IntelRD(NULL, output, sz)) {
                 /* success, we're done */
                 return 0;
             }
        #ifdef FORCE_FAILURE_RDSEED
             /* don't fall back to CryptoAPI */
             return READ_RAN_E;
        #endif
        }
    #endif /* HAVE_INTEL_RDSEED */

    if(!CryptAcquireContext(&os->handle, 0, 0, PROV_RSA_FULL,
                            CRYPT_VERIFYCONTEXT))
        return WINCRYPT_E;

    if (!CryptGenRandom(os->handle, sz, output))
        return CRYPTGEN_E;

    CryptReleaseContext(os->handle, 0);

    return 0;
}


#elif defined(HAVE_RTP_SYS) || defined(EBSNET)

#include "rtprand.h"   /* rtp_rand () */
#include "rtptime.h"   /* rtp_get_system_msec() */

int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
    word32 i;

    rtp_srand(rtp_get_system_msec());
    for (i = 0; i < sz; i++ ) {
        output[i] = rtp_rand() % 256;
    }

    return 0;
}

#elif (defined(WOLFSSL_ATMEL) || defined(WOLFSSL_ATECC_RNG)) && \
      !defined(WOLFSSL_PIC32MZ_RNG)
    /* enable ATECC RNG unless using PIC32MZ one instead */
    #include <wolfssl/wolfcrypt/port/atmel/atmel.h>

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;

        (void)os;
        if (output == NULL) {
            return BUFFER_E;
        }

        ret = atmel_get_random_number(sz, output);

        return ret;
    }

#elif defined(MICROCHIP_PIC32)

    #ifdef MICROCHIP_MPLAB_HARMONY
        #ifdef MICROCHIP_MPLAB_HARMONY_3
            #include "system/time/sys_time.h"
            #define PIC32_SEED_COUNT SYS_TIME_CounterGet
        #else
            #define PIC32_SEED_COUNT _CP0_GET_COUNT
        #endif
    #else
        #if !defined(WOLFSSL_MICROCHIP_PIC32MZ)
            #include <peripheral/timer.h>
        #endif
        extern word32 ReadCoreTimer(void);
        #define PIC32_SEED_COUNT ReadCoreTimer
    #endif

    #ifdef WOLFSSL_PIC32MZ_RNG
        #include "xc.h"
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            byte rnd[8];
            word32 *rnd32 = (word32 *)rnd;
            word32 size = sz;
            byte* op = output;

#if ((__PIC32_FEATURE_SET0 == 'E') && (__PIC32_FEATURE_SET1 == 'C'))
            RNGNUMGEN1 = _CP0_GET_COUNT();
            RNGPOLY1 = _CP0_GET_COUNT();
            RNGPOLY2 = _CP0_GET_COUNT();
            RNGNUMGEN2 = _CP0_GET_COUNT();
#else
            /* All others can be seeded from the TRNG */
            RNGCONbits.TRNGMODE = 1;
            RNGCONbits.TRNGEN = 1;
            while (RNGCNT < 64);
            RNGCONbits.LOAD = 1;
            while (RNGCONbits.LOAD == 1);
            while (RNGCNT < 64);
            RNGPOLY2 = RNGSEED2;
            RNGPOLY1 = RNGSEED1;
#endif

            RNGCONbits.PLEN = 0x40;
            RNGCONbits.PRNGEN = 1;
            for (i=0; i<5; i++) { /* wait for RNGNUMGEN ready */
                volatile int x, y;
                x = RNGNUMGEN1;
                y = RNGNUMGEN2;
                (void)x;
                (void)y;
            }
            do {
                rnd32[0] = RNGNUMGEN1;
                rnd32[1] = RNGNUMGEN2;

                for(i=0; i<8; i++, op++) {
                    *op = rnd[i];
                    size --;
                    if(size==0)break;
                }
            } while(size);
            return 0;
        }
    #else  /* WOLFSSL_PIC32MZ_RNG */
        /* uses the core timer, in nanoseconds to seed srand */
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            srand(PIC32_SEED_COUNT() * 25);

            for (i = 0; i < sz; i++ ) {
                output[i] = rand() % 256;
                if ( (i % 8) == 7)
                    srand(PIC32_SEED_COUNT() * 25);
            }
            return 0;
        }
    #endif /* WOLFSSL_PIC32MZ_RNG */

#elif defined(FREESCALE_K70_RNGA) || defined(FREESCALE_RNGA)
    /*
     * wc_Generates a RNG seed using the Random Number Generator Accelerator
     * on the Kinetis K70. Documentation located in Chapter 37 of
     * K70 Sub-Family Reference Manual (see Note 3 in the README for link).
     */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;

        /* turn on RNGA module */
        #if defined(SIM_SCGC3_RNGA_MASK)
            SIM_SCGC3 |= SIM_SCGC3_RNGA_MASK;
        #endif
        #if defined(SIM_SCGC6_RNGA_MASK)
            /* additionally needed for at least K64F */
            SIM_SCGC6 |= SIM_SCGC6_RNGA_MASK;
        #endif

        /* set SLP bit to 0 - "RNGA is not in sleep mode" */
        RNG_CR &= ~RNG_CR_SLP_MASK;

        /* set HA bit to 1 - "security violations masked" */
        RNG_CR |= RNG_CR_HA_MASK;

        /* set GO bit to 1 - "output register loaded with data" */
        RNG_CR |= RNG_CR_GO_MASK;

        for (i = 0; i < sz; i++) {

            /* wait for RNG FIFO to be full */
            while((RNG_SR & RNG_SR_OREG_LVL(0xF)) == 0) {}

            /* get value */
            output[i] = RNG_OR;
        }

        return 0;
    }

#elif defined(FREESCALE_K53_RNGB) || defined(FREESCALE_RNGB)
    /*
     * wc_Generates a RNG seed using the Random Number Generator (RNGB)
     * on the Kinetis K53. Documentation located in Chapter 33 of
     * K53 Sub-Family Reference Manual (see note in the README for link).
     */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;

        /* turn on RNGB module */
        SIM_SCGC3 |= SIM_SCGC3_RNGB_MASK;

        /* reset RNGB */
        RNG_CMD |= RNG_CMD_SR_MASK;

        /* FIFO generate interrupt, return all zeros on underflow,
         * set auto reseed */
        RNG_CR |= (RNG_CR_FUFMOD_MASK | RNG_CR_AR_MASK);

        /* gen seed, clear interrupts, clear errors */
        RNG_CMD |= (RNG_CMD_GS_MASK | RNG_CMD_CI_MASK | RNG_CMD_CE_MASK);

        /* wait for seeding to complete */
        while ((RNG_SR & RNG_SR_SDN_MASK) == 0) {}

        for (i = 0; i < sz; i++) {

            /* wait for a word to be available from FIFO */
            while((RNG_SR & RNG_SR_FIFO_LVL_MASK) == 0) {}

            /* get value */
            output[i] = RNG_OUT;
        }

        return 0;
    }

#elif defined(FREESCALE_KSDK_2_0_TRNG)
    #ifndef TRNG0
    #define TRNG0 TRNG
    #endif

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        status_t status;
        status = TRNG_GetRandomData(TRNG0, output, sz);
        (void)os;
        if (status == kStatus_Success)
        {
            return(0);
        }
        return RAN_BLOCK_E;
    }

#elif defined(FREESCALE_KSDK_2_0_RNGA)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        status_t status;
        status = RNGA_GetRandomData(RNG, output, sz);
        (void)os;
        if (status == kStatus_Success)
        {
            return(0);
        }
        return RAN_BLOCK_E;
    }


#elif defined(FREESCALE_RNGA)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        status_t status;
        status = RNGA_GetRandomData(RNG, output, sz);
        (void)os;
        if (status == kStatus_Success)
        {
            return(0);
        }
        return RAN_BLOCK_E;
    }

#elif defined(FREESCALE_MQX) || defined(FREESCALE_KSDK_MQX) || \
    defined(FREESCALE_KSDK_BM) || defined(FREESCALE_FREE_RTOS)
    /*
     * Fallback to USE_TEST_GENSEED if a FREESCALE platform did not match any
     * of the TRNG/RNGA/RNGB support
     */
    #define USE_TEST_GENSEED

#elif defined(WOLFSSL_SILABS_SE_ACCEL)
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;
        return silabs_GenerateRand(output, sz);
    }

#elif defined(STM32_RNG)
     /* Generate a RNG seed using the hardware random number generator
      * on the STM32F2/F4/F7/L4. */

    #ifdef WOLFSSL_STM32_CUBEMX
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        RNG_HandleTypeDef hrng;
        word32 i = 0;
        (void)os;

        ret = wolfSSL_CryptHwMutexLock();
        if (ret != 0) {
            return ret;
        }

        /* enable RNG clock source */
        __HAL_RCC_RNG_CLK_ENABLE();

        /* enable RNG peripheral */
        XMEMSET(&hrng, 0, sizeof(hrng));
        hrng.Instance = RNG;
        HAL_RNG_Init(&hrng);

        while (i < sz) {
            /* If not aligned or there is odd/remainder */
            if( (i + sizeof(word32)) > sz ||
                ((wc_ptr_t)&output[i] % sizeof(word32)) != 0
            ) {
                /* Single byte at a time */
                uint32_t tmpRng = 0;
                if (HAL_RNG_GenerateRandomNumber(&hrng, &tmpRng) != HAL_OK) {
                    wolfSSL_CryptHwMutexUnLock();
                    return RAN_BLOCK_E;
                }
                output[i++] = (byte)tmpRng;
            }
            else {
                /* Use native 32 instruction */
                if (HAL_RNG_GenerateRandomNumber(&hrng, (uint32_t*)&output[i]) != HAL_OK) {
                    wolfSSL_CryptHwMutexUnLock();
                    return RAN_BLOCK_E;
                }
                i += sizeof(word32);
            }
        }

        HAL_RNG_DeInit(&hrng);

        wolfSSL_CryptHwMutexUnLock();

        return 0;
    }
    #elif defined(WOLFSSL_STM32F427_RNG) || defined(WOLFSSL_STM32_RNG_NOLIB)

    /* Generate a RNG seed using the hardware RNG on the STM32F427
     * directly, following steps outlined in STM32F4 Reference
     * Manual (Chapter 24) for STM32F4xx family. */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        word32 i;
        (void)os;

        ret = wolfSSL_CryptHwMutexLock();
        if (ret != 0) {
            return ret;
        }

        /* enable RNG peripheral clock */
        RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN;

        /* enable RNG interrupt, set IE bit in RNG->CR register */
        RNG->CR |= RNG_CR_IE;

        /* enable RNG, set RNGEN bit in RNG->CR. Activates RNG,
         * RNG_LFSR, and error detector */
        RNG->CR |= RNG_CR_RNGEN;

        /* verify no errors, make sure SEIS and CEIS bits are 0
         * in RNG->SR register */
        if (RNG->SR & (RNG_SR_SECS | RNG_SR_CECS)) {
            wolfSSL_CryptHwMutexUnLock();
            return RNG_FAILURE_E;
        }

        for (i = 0; i < sz; i++) {
            /* wait until RNG number is ready */
            while ((RNG->SR & RNG_SR_DRDY) == 0) { }

            /* get value */
            output[i] = RNG->DR;
        }

        wolfSSL_CryptHwMutexUnLock();

        return 0;
    }

    #else

    /* Generate a RNG seed using the STM32 Standard Peripheral Library */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        word32 i;
        (void)os;

        ret = wolfSSL_CryptHwMutexLock();
        if (ret != 0) {
            return ret;
        }

        /* enable RNG clock source */
        RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_RNG, ENABLE);

        /* reset RNG */
        RNG_DeInit();

        /* enable RNG peripheral */
        RNG_Cmd(ENABLE);

        /* verify no errors with RNG_CLK or Seed */
        if (RNG_GetFlagStatus(RNG_FLAG_SECS | RNG_FLAG_CECS) != RESET) {
            wolfSSL_CryptHwMutexUnLock();
            return RNG_FAILURE_E;
        }

        for (i = 0; i < sz; i++) {
            /* wait until RNG number is ready */
            while (RNG_GetFlagStatus(RNG_FLAG_DRDY) == RESET) { }

            /* get value */
            output[i] = RNG_GetRandomNumber();
        }

        wolfSSL_CryptHwMutexUnLock();

        return 0;
    }
    #endif /* WOLFSSL_STM32_CUBEMX */

#elif defined(WOLFSSL_TIRTOS)
    #warning "potential for not enough entropy, currently being used for testing"
    #include <xdc/runtime/Timestamp.h>
    #include <stdlib.h>
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;
        srand(xdc_runtime_Timestamp_get32());

        for (i = 0; i < sz; i++ ) {
            output[i] = rand() % 256;
            if ((i % 8) == 7) {
                srand(xdc_runtime_Timestamp_get32());
            }
        }

        return 0;
    }

#elif defined(WOLFSSL_PB)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;
        for (i = 0; i < sz; i++)
            output[i] = UTL_Rand();

        (void)os;

        return 0;
    }

#elif defined(WOLFSSL_NUCLEUS)
#include "nucleus.h"
#include "kernel/plus_common.h"

#warning "potential for not enough entropy, currently being used for testing"
int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
    int i;
    srand(NU_Get_Time_Stamp());

    for (i = 0; i < sz; i++ ) {
        output[i] = rand() % 256;
        if ((i % 8) == 7) {
            srand(NU_Get_Time_Stamp());
        }
    }

    return 0;
}
#elif defined(WOLFSSL_DEOS) && !defined(CUSTOM_RAND_GENERATE)
    #include "stdlib.h"

    #warning "potential for not enough entropy, currently being used for testing Deos"
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;
        int seed = XTIME(0);
        (void)os;

        for (i = 0; i < sz; i++ ) {
            output[i] = rand_r(&seed) % 256;
            if ((i % 8) == 7) {
                seed = XTIME(0);
                rand_r(&seed);
            }
        }

        return 0;
    }
#elif defined(WOLFSSL_VXWORKS)
    #ifdef WOLFSSL_VXWORKS_6_x
        #include "stdlib.h"
        #warning "potential for not enough entropy, currently being used for testing"
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            unsigned int seed = (unsigned int)XTIME(0);
            (void)os;

            for (i = 0; i < sz; i++ ) {
                output[i] = rand_r(&seed) % 256;
                if ((i % 8) == 7) {
                    seed = (unsigned int)XTIME(0);
                    rand_r(&seed);
                }
            }

            return 0;
        }
    #else
        #include <randomNumGen.h>
        #include <tickLib.h>

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz) {
            STATUS                status   = ERROR;
            RANDOM_NUM_GEN_STATUS r_status = RANDOM_NUM_GEN_ERROR;
            _Vx_ticks_t           seed = 0;

            #ifdef VXWORKS_SIM
                /* cannot generate true entropy with VxWorks simulator */
                #warning "not enough entropy, simulator for testing only"
                int i = 0;

                for (i = 0; i < 1000; i++) {
                    randomAddTimeStamp();
                }
            #endif

            /*
              wolfSSL can request 52 Bytes of random bytes. We need to add
              buffer to the entropy pool to ensure we can get more than 32 Bytes.
              Because VxWorks has entropy limits (ENTROPY_MIN and ENTROPY_MAX)
              defined as 256 and 1024 bits, see randomSWNumGenLib.c.

              randStatus() can return the following status:
              RANDOM_NUM_GEN_NO_ENTROPY when entropy is 0
              RANDOM_NUM_GEN_ERROR, entropy is not initialized
              RANDOM_NUM_GEN_NOT_ENOUGH_ENTROPY if entropy < 32 Bytes
              RANDOM_NUM_GEN_ENOUGH_ENTROPY if entropy is between 32 and 128 Bytes
              RANDOM_NUM_GEN_MAX_ENTROPY if entropy is greater than 128 Bytes
            */

            do {
                seed = tickGet();
                status = randAdd(&seed, sizeof(_Vx_ticks_t), 2);
                if (status == OK)
                    r_status = randStatus();

            } while (r_status != RANDOM_NUM_GEN_MAX_ENTROPY &&
                     r_status != RANDOM_NUM_GEN_ERROR && status == OK);

            if (r_status == RANDOM_NUM_GEN_ERROR)
                return RNG_FAILURE_E;

            status = randBytes (output, sz);

            if (status == ERROR) {
                return RNG_FAILURE_E;
            }

            return 0;
        }
    #endif
#elif defined(WOLFSSL_NRF51) || defined(WOLFSSL_NRF5x)
    #include "app_error.h"
    #include "nrf_drv_rng.h"
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int remaining = sz, length, pos = 0;
        word32 err_code;
        byte available;
        static byte initialized = 0;

        (void)os;

        /* Make sure RNG is running */
        if (!initialized) {
            err_code = nrf_drv_rng_init(NULL);
            if (err_code != NRF_SUCCESS && err_code != NRF_ERROR_INVALID_STATE
            #ifdef NRF_ERROR_MODULE_ALREADY_INITIALIZED
                && err_code != NRF_ERROR_MODULE_ALREADY_INITIALIZED
            #endif
            ) {
                return -1;
            }
            initialized = 1;
        }

        while (remaining > 0) {
            available = 0;
            nrf_drv_rng_bytes_available(&available); /* void func */
            length = (remaining < available) ? remaining : available;
            if (length > 0) {
                err_code = nrf_drv_rng_rand(&output[pos], length);
                if (err_code != NRF_SUCCESS) {
                    break;
                }
                remaining -= length;
                pos += length;
            }
        }

        return (err_code == NRF_SUCCESS) ? 0 : -1;
    }

#elif defined(HAVE_WNR)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        if (os == NULL || output == NULL || wnr_ctx == NULL ||
                wnr_timeout < 0) {
            return BAD_FUNC_ARG;
        }

        if (wnr_mutex_init == 0) {
            WOLFSSL_MSG("netRandom context must be created before use");
            return RNG_FAILURE_E;
        }

        if (wc_LockMutex(&wnr_mutex) != 0) {
            WOLFSSL_MSG("Bad Lock Mutex wnr_mutex");
            return BAD_MUTEX_E;
        }

        if (wnr_get_entropy(wnr_ctx, wnr_timeout, output, sz, sz) !=
                WNR_ERROR_NONE)
            return RNG_FAILURE_E;

        wc_UnLockMutex(&wnr_mutex);

        return 0;
    }

#elif defined(INTIME_RTOS)
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        uint32_t randval;
        word32 len;

        if (output == NULL) {
            return BUFFER_E;
        }

    #ifdef INTIMEVER
        /* If INTIMEVER exists then it is INTIME RTOS v6 or later */
        #define INTIME_RAND_FUNC arc4random
        len = 4;
    #else
        /* v5 and older */
        #define INTIME_RAND_FUNC rand
        srand(time(0));
        len = 2; /* don't use all 31 returned bits */
    #endif

        while (sz > 0) {
            if (sz < len)
                len = sz;
            randval = INTIME_RAND_FUNC();
            XMEMCPY(output, &randval, len);
            output += len;
            sz -= len;
        }
        (void)os;

        return 0;
    }

#elif defined(WOLFSSL_WICED)
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        (void)os;

        if (output == NULL || UINT16_MAX < sz) {
            return BUFFER_E;
        }

        if ((ret = wiced_crypto_get_random((void*) output, sz) )
                         != WICED_SUCCESS) {
            return ret;
        }

        return ret;
    }

#elif defined(WOLFSSL_NETBURNER)
    #warning using NetBurner pseudo random GetRandomByte for seed
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;
        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }

        for (i = 0; i < sz; i++) {
            output[i] = GetRandomByte();

            /* check if was a valid random number */
            if (!RandomValid())
                return RNG_FAILURE_E;
        }

        return 0;
    }
#elif defined(IDIRECT_DEV_RANDOM)

    extern int getRandom( int sz, unsigned char *output );

    int GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int num_bytes_returned = 0;

        num_bytes_returned = getRandom( (int) sz, (unsigned char *) output );

        return 0;
    }

#elif (defined(WOLFSSL_IMX6_CAAM) || defined(WOLFSSL_IMX6_CAAM_RNG) || \
       defined(WOLFSSL_SECO_CAAM) || defined(WOLFSSL_QNX_CAAM))

    #include <wolfssl/wolfcrypt/port/caam/wolfcaam.h>

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        unsigned int args[4] = {0};
        CAAM_BUFFER buf[1];
        int ret    = 0;
        int times  = 1000, i; /* 1000 is an arbitrary number chosen */
        word32 idx = 0;

        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }

        /* Check Waiting to make sure entropy is ready */
        for (i = 0; i < times; i++) {
            buf[0].BufferType = DataBuffer | LastBuffer;
            buf[0].TheAddress = (CAAM_ADDRESS)(output + idx);
            buf[0].Length     = ((sz - idx) < WC_CAAM_MAX_ENTROPY)?
                                sz - idx : WC_CAAM_MAX_ENTROPY;

            args[0] = buf[0].Length;
            ret = wc_caamAddAndWait(buf, 1, args, CAAM_ENTROPY);
            if (ret == 0) {
                idx += buf[0].Length;
                if (idx == sz)
                    break;
            }

            /* driver could be waiting for entropy */
            if (ret != RAN_BLOCK_E && ret != 0) {
                return ret;
            }
            usleep(100);
        }

        if (i == times && ret != 0) {
             return RNG_FAILURE_E;
        }
        else { /* Success case */
            ret = 0;
        }

        return ret;
    }

#elif defined(WOLFSSL_APACHE_MYNEWT)

    #include <stdlib.h>
    #include "os/os_time.h"
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;
        srand(os_time_get());

        for (i = 0; i < sz; i++ ) {
            output[i] = rand() % 256;
            if ((i % 8) == 7) {
                srand(os_time_get());
            }
        }

        return 0;
    }

#elif defined(WOLFSSL_ESPIDF)

    /* Espressif */
    #if defined(WOLFSSL_ESPWROOM32) || defined(WOLFSSL_ESPWROOM32SE)

        /* Espressif ESP32 */
        #include <esp_system.h>

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            word32 rand;
            while (sz > 0) {
                word32 len = sizeof(rand);
                if (sz < len)
                    len = sz;
                /* Get one random 32-bit word from hw RNG */
                rand = esp_random( );
                XMEMCPY(output, &rand, len);
                output += len;
                sz -= len;
            }

            return 0;
        }

    #elif defined(WOLFSSL_ESP8266)

        /* Espressif ESP8266 */
        #include <esp_system.h>

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            word32 rand;
            while (sz > 0) {
                word32 len = sizeof(rand);
                if (sz < len)
                    len = sz;
                /* Get one random 32-bit word from hw RNG */
                rand = esp_random( );
                XMEMCPY(output, &rand, len);
                output += len;
                sz -= len;
            }

            return 0;
        }
    #endif /* end WOLFSSL_ESPWROOM32 */

#elif defined(WOLFSSL_LINUXKM)
    #include <linux/random.h>
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;

        get_random_bytes(output, sz);

        return 0;
    }

#elif defined(WOLFSSL_RENESAS_TSIP)
#if defined(WOLFSSL_RENESA_TSIP_IAREWRX)
   #include "r_bsp/mcu/all/r_rx_compiler.h"
#endif
   #include "r_bsp/platform.h"
    #include "r_tsip_rx_if.h"

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;
        word32 buffer[4];

        while (sz > 0) {
            word32 len = sizeof(buffer);

            if (sz < len) {
                len = sz;
            }
            /* return 4 words random number*/
            ret = R_TSIP_GenerateRandomNumber((uint32_t*)buffer);
            if(ret == TSIP_SUCCESS) {
                XMEMCPY(output, &buffer, len);
                output += len;
                sz -= len;
            } else
                return ret;
        }
        return ret;
    }
#elif defined(WOLFSSL_RENESAS_SCEPROTECT)
    #include "r_sce.h"

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;
        word32 buffer[4];

        while (sz > 0) {
            word32 len = sizeof(buffer);

            if (sz < len) {
                len = sz;
            }
            /* return 4 words random number*/
            ret = R_SCE_RandomNumberGenerate(buffer);
            if(ret == FSP_SUCCESS) {
                XMEMCPY(output, &buffer, len);
                output += len;
                sz -= len;
            } else
                return ret;
        }
        return ret;
    }

#elif defined(WOLFSSL_SCE) && !defined(WOLFSSL_SCE_NO_TRNG)
    #include "hal_data.h"

    #ifndef WOLFSSL_SCE_TRNG_HANDLE
        #define WOLFSSL_SCE_TRNG_HANDLE g_sce_trng
    #endif

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 ret;
        word32 blocks;
        word32 len = sz;

        ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->open(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl,
                                                  WOLFSSL_SCE_TRNG_HANDLE.p_cfg);
        if (ret != SSP_SUCCESS && ret != SSP_ERR_CRYPTO_ALREADY_OPEN) {
            /* error opening TRNG driver */
            return -1;
        }

        blocks = sz / sizeof(word32);
        if (blocks > 0) {
            ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->read(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl,
                                                       (word32*)output, blocks);
            if (ret != SSP_SUCCESS) {
                return -1;
            }
        }

        len = len - (blocks * sizeof(word32));
        if (len > 0) {
            word32 tmp;

            if (len > sizeof(word32)) {
                return -1;
            }
            ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->read(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl,
                                                      (word32*)&tmp, 1);
            if (ret != SSP_SUCCESS) {
                return -1;
            }
            XMEMCPY(output + (blocks * sizeof(word32)), (byte*)&tmp, len);
        }

        ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->close(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl);
        if (ret != SSP_SUCCESS) {
            /* error opening TRNG driver */
            return -1;
        }
        return 0;
    }
#elif defined(CUSTOM_RAND_GENERATE_BLOCK)
    /* #define CUSTOM_RAND_GENERATE_BLOCK myRngFunc
     * extern int myRngFunc(byte* output, word32 sz);
     */

#elif defined(WOLFSSL_SAFERTOS) || defined(WOLFSSL_LEANPSK) || \
      defined(WOLFSSL_IAR_ARM)  || defined(WOLFSSL_MDK_ARM) || \
      defined(WOLFSSL_uITRON4)  || defined(WOLFSSL_uTKERNEL2) || \
      defined(WOLFSSL_LPC43xx)  || defined(NO_STM32_RNG) || \
      defined(MBED)             || defined(WOLFSSL_EMBOS) || \
      defined(WOLFSSL_GENSEED_FORTEST) || defined(WOLFSSL_CHIBIOS) || \
      defined(WOLFSSL_CONTIKI)  || defined(WOLFSSL_AZSPHERE)

    /* these platforms do not have a default random seed and
       you'll need to implement your own wc_GenerateSeed or define via
       CUSTOM_RAND_GENERATE_BLOCK */

    #define USE_TEST_GENSEED

#elif defined(WOLFSSL_ZEPHYR)

        #include <random/rand32.h>
    #ifndef _POSIX_C_SOURCE
        #include <posix/time.h>
    #else
        #include <sys/time.h>
    #endif

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            sys_rand_get(output, sz);
            return 0;
        }

#elif defined(WOLFSSL_TELIT_M2MB)

        #include "stdlib.h"
        static long get_timestamp(void) {
            long myTime = 0;
            INT32 fd = m2mb_rtc_open("/dev/rtc0", 0);
            if (fd >= 0) {
                M2MB_RTC_TIMEVAL_T timeval;
                m2mb_rtc_ioctl(fd, M2MB_RTC_IOCTL_GET_TIMEVAL, &timeval);
                myTime = timeval.msec;
                m2mb_rtc_close(fd);
            }
            return myTime;
        }
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            srand(get_timestamp());
            for (i = 0; i < sz; i++ ) {
                output[i] = rand() % 256;
                if ((i % 8) == 7) {
                    srand(get_timestamp());
                }
            }
            return 0;
        }
#elif defined(WOLFSSL_SE050)
     #include <wolfssl/wolfcrypt/port/nxp/se050_port.h>

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz){
        int ret = 0;

        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }
        ret = wolfSSL_CryptHwMutexLock();
        if (ret == 0) {
            ret = se050_get_random_number(sz, output);
            wolfSSL_CryptHwMutexUnLock();
        }
        return ret;
    }

#elif defined(DOLPHIN_EMULATOR)

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            word32 i;
            (void)os;
            srand(time(NULL));
            for (i = 0; i < sz; i++)
                output[i] = (byte)rand();
            return 0;
        }

#elif defined(WOLFSSL_GETRANDOM)

    /* getrandom() was added to the Linux kernel in version 3.17.
     * Added to glibc in version 2.25. */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;
        int len = 0;
        (void)os;

        while (sz) {
            errno = 0;
            len = (int)getrandom(output, sz, 0);
            if (len == -1) {
                if (errno == EINTR) {
                    /* interrupted, call getrandom again */
                    continue;
                }
                else {
                    ret = READ_RAN_E;
                }
                break;
            }

            sz     -= len;
            output += len;
        }
        return ret;
    }

#elif defined(NO_DEV_RANDOM)

    #error "you need to write an os specific wc_GenerateSeed() here"

    /*
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        return 0;
    }
    */

#else

    /* may block */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;

        if (os == NULL) {
            return BAD_FUNC_ARG;
        }

    #ifdef WOLF_CRYPTO_CB
        if (os->devId != INVALID_DEVID) {
            ret = wc_CryptoCb_RandomSeed(os, output, sz);
            if (ret != CRYPTOCB_UNAVAILABLE)
                return ret;
            /* fall-through when unavailable */
            ret = 0; /* reset error code */
        }
    #endif

    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)
        if (IS_INTEL_RDSEED(intel_flags)) {
             ret = wc_GenerateSeed_IntelRD(NULL, output, sz);
             if (ret == 0) {
                 /* success, we're done */
                 return ret;
             }
        #ifdef FORCE_FAILURE_RDSEED
             /* don't fallback to /dev/urandom */
             return ret;
        #else
             /* reset error and fallback to using /dev/urandom */
             ret = 0;
        #endif
        }
    #endif /* HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */

    #ifndef NO_DEV_URANDOM /* way to disable use of /dev/urandom */
        os->fd = open("/dev/urandom", O_RDONLY);
        if (os->fd == -1)
    #endif
        {
            /* may still have /dev/random */
            os->fd = open("/dev/random", O_RDONLY);
            if (os->fd == -1)
                return OPEN_RAN_E;
        }

        while (sz) {
            int len = (int)read(os->fd, output, sz);
            if (len == -1) {
                ret = READ_RAN_E;
                break;
            }

            sz     -= len;
            output += len;

            if (sz) {
    #if defined(BLOCKING) || defined(WC_RNG_BLOCKING)
                sleep(0);             /* context switch */
    #else
                ret = RAN_BLOCK_E;
                break;
    #endif
            }
        }
        close(os->fd);

        return ret;
    }

#endif

#ifdef USE_TEST_GENSEED
    #ifndef _MSC_VER
        #warning "write a real random seed!!!!, just for testing now"
    #else
        #pragma message("Warning: write a real random seed!!!!, just for testing now")
    #endif
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;
        for (i = 0; i < sz; i++ )
            output[i] = i;

        (void)os;

        return 0;
    }
#endif
/* End wc_GenerateSeed */

#if defined(CUSTOM_RAND_GENERATE_BLOCK) && defined(WOLFSSL_KCAPI)
#include <fcntl.h>
int wc_hwrng_generate_block(byte *output, word32 sz)
{
    int fd;
    int len;
    int ret = 0;
    fd = open("/dev/hwrng", O_RDONLY);
    if (fd == -1)
        return OPEN_RAN_E;
    while(sz)
    {
        len = (int)read(fd, output, sz);
        if (len == -1)
        {
            ret = READ_RAN_E;
            break;
        }
        sz -= len;
        output += len;
    }
    close(fd);
    return ret;
}
#endif

#endif /* WC_NO_RNG */
#endif /* HAVE_FIPS */