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/*

 *  CTR_DRBG implementation based on AES-256 (NIST SP 800-90)

 *

 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved

 *  SPDX-License-Identifier: GPL-2.0

 *

 *  This program 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.

 *

 *  This program 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 02110-1301 USA.

 *

 *  This file is part of mbed TLS (https://tls.mbed.org)

 */

/*

 *  The NIST SP 800-90 DRBGs are described in the following publication.

 *

 *  http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf

 */

#if !defined(MBEDTLS_CONFIG_FILE)

#include "mbedtls/config.h"

#else

#include MBEDTLS_CONFIG_FILE

#endif

#if defined(MBEDTLS_CTR_DRBG_C)

#include "mbedtls/ctr_drbg.h"

#include "mbedtls/platform_util.h"

#include 

#if defined(MBEDTLS_FS_IO)

#include 

#endif

#if defined(MBEDTLS_SELF_TEST)

#if defined(MBEDTLS_PLATFORM_C)

#include "mbedtls/platform.h"

#else

#include 

#define mbedtls_printf printf

#endif /* MBEDTLS_PLATFORM_C */

#endif /* MBEDTLS_SELF_TEST */

/*

 * CTR_DRBG context initialization

 */

void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx )

{

    memset( ctx, 0, sizeof( mbedtls_ctr_drbg_context ) );

#if defined(MBEDTLS_THREADING_C)

    mbedtls_mutex_init( &ctx->mutex );

#endif

}

void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )

{

    if( ctx == NULL )

        return;

#if defined(MBEDTLS_THREADING_C)

    mbedtls_mutex_free( &ctx->mutex );

#endif

    mbedtls_aes_free( &ctx->aes_ctx );

    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ctr_drbg_context ) );

}

void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, int resistance )

{

    ctx->prediction_resistance = resistance;

}

void mbedtls_ctr_drbg_set_entropy_len( mbedtls_ctr_drbg_context *ctx, size_t len )

{

    ctx->entropy_len = len;

}

void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx, int interval )

{

    ctx->reseed_interval = interval;

}

static int block_cipher_df( unsigned char *output,

                            const unsigned char *data, size_t data_len )

{

    unsigned char buf[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16];

    unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN];

    unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];

    unsigned char chain[MBEDTLS_CTR_DRBG_BLOCKSIZE];

    unsigned char *p, *iv;

    mbedtls_aes_context aes_ctx;

    int ret = 0;

    int i, j;

    size_t buf_len, use_len;

    if( data_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )

        return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );

    memset( buf, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16 );

    mbedtls_aes_init( &aes_ctx );

    /*

     * Construct IV (16 bytes) and S in buffer

     * IV = Counter (in 32-bits) padded to 16 with zeroes

     * S = Length input string (in 32-bits) || Length of output (in 32-bits) ||

     *     data || 0x80

     *     (Total is padded to a multiple of 16-bytes with zeroes)

     */

    p = buf + MBEDTLS_CTR_DRBG_BLOCKSIZE;

    *p++ = ( data_len >> 24 ) & 0xff;

    *p++ = ( data_len >> 16 ) & 0xff;

    *p++ = ( data_len >> 8  ) & 0xff;

    *p++ = ( data_len       ) & 0xff;

    p += 3;

    *p++ = MBEDTLS_CTR_DRBG_SEEDLEN;

    memcpy( p, data, data_len );

    p[data_len] = 0x80;

    buf_len = MBEDTLS_CTR_DRBG_BLOCKSIZE + 8 + data_len + 1;

    for( i = 0; i < MBEDTLS_CTR_DRBG_KEYSIZE; i++ )

        key[i] = i;

    if( ( ret = mbedtls_aes_setkey_enc( &aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )

    {

        goto exit;

    }

    /*

     * Reduce data to MBEDTLS_CTR_DRBG_SEEDLEN bytes of data

     */

    for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE )

    {

        p = buf;

        memset( chain, 0, MBEDTLS_CTR_DRBG_BLOCKSIZE );

        use_len = buf_len;

        while( use_len > 0 )

        {

            for( i = 0; i < MBEDTLS_CTR_DRBG_BLOCKSIZE; i++ )

                chain[i] ^= p[i];

            p += MBEDTLS_CTR_DRBG_BLOCKSIZE;

            use_len -= ( use_len >= MBEDTLS_CTR_DRBG_BLOCKSIZE ) ?

                       MBEDTLS_CTR_DRBG_BLOCKSIZE : use_len;

            if( ( ret = mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT, chain, chain ) ) != 0 )

            {

                goto exit;

            }

        }

        memcpy( tmp + j, chain, MBEDTLS_CTR_DRBG_BLOCKSIZE );

        /*

         * Update IV

         */

        buf[3]++;

    }

    /*

     * Do final encryption with reduced data

     */

    if( ( ret = mbedtls_aes_setkey_enc( &aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )

    {

        goto exit;

    }

    iv = tmp + MBEDTLS_CTR_DRBG_KEYSIZE;

    p = output;

    for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE )

    {

        if( ( ret = mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT, iv, iv ) ) != 0 )

        {

            goto exit;

        }

        memcpy( p, iv, MBEDTLS_CTR_DRBG_BLOCKSIZE );

        p += MBEDTLS_CTR_DRBG_BLOCKSIZE;

    }

exit:

    mbedtls_aes_free( &aes_ctx );

    /*

    * tidy up the stack

    */

    mbedtls_platform_zeroize( buf, sizeof( buf ) );

    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );

    mbedtls_platform_zeroize( key, sizeof( key ) );

    mbedtls_platform_zeroize( chain, sizeof( chain ) );

    if( 0 != ret )

    {

        /*

        * wipe partial seed from memory

        */

        mbedtls_platform_zeroize( output, MBEDTLS_CTR_DRBG_SEEDLEN );

    }

    return( ret );

}

/* CTR_DRBG_Update (SP 800-90A §10.2.1.2)

 * ctr_drbg_update_internal(ctx, provided_data)

 * implements

 * CTR_DRBG_Update(provided_data, Key, V)

 * with inputs and outputs

 *   ctx->aes_ctx = Key

 *   ctx->counter = V

 */

static int ctr_drbg_update_internal( mbedtls_ctr_drbg_context *ctx,

                              const unsigned char data[MBEDTLS_CTR_DRBG_SEEDLEN] )

{

    unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN];

    unsigned char *p = tmp;

    int i, j;

    int ret = 0;

    memset( tmp, 0, MBEDTLS_CTR_DRBG_SEEDLEN );

    for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE )

    {

        /*

         * Increase counter

         */

        for( i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i-- )

            if( ++ctx->counter[i - 1] != 0 )

                break;

        /*

         * Crypt counter block

         */

        if( ( ret = mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, p ) ) != 0 )

            goto exit;

        p += MBEDTLS_CTR_DRBG_BLOCKSIZE;

    }

    for( i = 0; i < MBEDTLS_CTR_DRBG_SEEDLEN; i++ )

        tmp[i] ^= data[i];

    /*

     * Update key and counter

     */

    if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )

        goto exit;

    memcpy( ctx->counter, tmp + MBEDTLS_CTR_DRBG_KEYSIZE, MBEDTLS_CTR_DRBG_BLOCKSIZE );

exit:

    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );

    return( ret );

}

/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2)

 * mbedtls_ctr_drbg_update(ctx, additional, add_len)

 * implements

 * CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,

 *                      security_strength) -> initial_working_state

 * with inputs

 *   ctx->counter = all-bits-0

 *   ctx->aes_ctx = context from all-bits-0 key

 *   additional[:add_len] = entropy_input || nonce || personalization_string

 * and with outputs

 *   ctx = initial_working_state

 */

int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx,

                                 const unsigned char *additional,

                                 size_t add_len )

{

    unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];

    int ret;

    if( add_len == 0 )

        return( 0 );

    if( ( ret = block_cipher_df( add_input, additional, add_len ) ) != 0 )

        goto exit;

    if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )

        goto exit;

exit:

    mbedtls_platform_zeroize( add_input, sizeof( add_input ) );

    return( ret );

}

#if !defined(MBEDTLS_DEPRECATED_REMOVED)

void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,

                              const unsigned char *additional,

                              size_t add_len )

{

    /* MAX_INPUT would be more logical here, but we have to match

     * block_cipher_df()'s limits since we can't propagate errors */

    if( add_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )

        add_len = MBEDTLS_CTR_DRBG_MAX_SEED_INPUT;

    (void) mbedtls_ctr_drbg_update_ret( ctx, additional, add_len );

}

#endif /* MBEDTLS_DEPRECATED_REMOVED */

/* CTR_DRBG_Reseed with derivation function (SP 800-90A §10.2.1.4.2)

 * mbedtls_ctr_drbg_reseed(ctx, additional, len)

 * implements

 * CTR_DRBG_Reseed(working_state, entropy_input, additional_input)

 *                -> new_working_state

 * with inputs

 *   ctx contains working_state

 *   additional[:len] = additional_input

 * and entropy_input comes from calling ctx->f_entropy

 * and with output

 *   ctx contains new_working_state

 */

int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx,

                     const unsigned char *additional, size_t len )

{

    unsigned char seed[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT];

    size_t seedlen = 0;

    int ret;

    if( ctx->entropy_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT ||

        len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT - ctx->entropy_len )

        return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );

    memset( seed, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT );

    /*

     * Gather entropy_len bytes of entropy to seed state

     */

    if( 0 != ctx->f_entropy( ctx->p_entropy, seed,

                             ctx->entropy_len ) )

    {

        return( MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED );

    }

    seedlen += ctx->entropy_len;

    /*

     * Add additional data

     */

    if( additional && len )

    {

        memcpy( seed + seedlen, additional, len );

        seedlen += len;

    }

    /*

     * Reduce to 384 bits

     */

    if( ( ret = block_cipher_df( seed, seed, seedlen ) ) != 0 )

        goto exit;

    /*

     * Update state

     */

    if( ( ret = ctr_drbg_update_internal( ctx, seed ) ) != 0 )

        goto exit;

    ctx->reseed_counter = 1;

exit:

    mbedtls_platform_zeroize( seed, sizeof( seed ) );

    return( ret );

}

/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2)

 * mbedtls_ctr_drbg_seed(ctx, f_entropy, p_entropy, custom, len)

 * implements

 * CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,

 *                      security_strength) -> initial_working_state

 * with inputs

 *   custom[:len] = nonce || personalization_string

 * where entropy_input comes from f_entropy for ctx->entropy_len bytes

 * and with outputs

 *   ctx = initial_working_state

 */

int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,

                           int (*f_entropy)(void *, unsigned char *, size_t),

                           void *p_entropy,

                           const unsigned char *custom,

                           size_t len )

{

    int ret;

    unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];

    memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );

    mbedtls_aes_init( &ctx->aes_ctx );

    ctx->f_entropy = f_entropy;

    ctx->p_entropy = p_entropy;

    if( ctx->entropy_len == 0 )

        ctx->entropy_len = MBEDTLS_CTR_DRBG_ENTROPY_LEN;

    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;

    /*

     * Initialize with an empty key

     */

    if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )

    {

        return( ret );

    }

    if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 )

    {

        return( ret );

    }

    return( 0 );

}

/* Backward compatibility wrapper */

int mbedtls_ctr_drbg_seed_entropy_len(

    mbedtls_ctr_drbg_context *ctx,

    int (*f_entropy)(void *, unsigned char *, size_t), void *p_entropy,

    const unsigned char *custom, size_t len,

    size_t entropy_len )

{

    mbedtls_ctr_drbg_set_entropy_len( ctx, entropy_len );

    return( mbedtls_ctr_drbg_seed( ctx, f_entropy, p_entropy, custom, len ) );

}

/* CTR_DRBG_Generate with derivation function (SP 800-90A §10.2.1.5.2)

 * mbedtls_ctr_drbg_random_with_add(ctx, output, output_len, additional, add_len)

 * implements

 * CTR_DRBG_Reseed(working_state, entropy_input, additional[:add_len])

 *                -> working_state_after_reseed

 *                if required, then

 * CTR_DRBG_Generate(working_state_after_reseed,

 *                   requested_number_of_bits, additional_input)

 *                -> status, returned_bits, new_working_state

 * with inputs

 *   ctx contains working_state

 *   requested_number_of_bits = 8 * output_len

 *   additional[:add_len] = additional_input

 * and entropy_input comes from calling ctx->f_entropy

 * and with outputs

 *   status = SUCCESS (this function does the reseed internally)

 *   returned_bits = output[:output_len]

 *   ctx contains new_working_state

 */

int mbedtls_ctr_drbg_random_with_add( void *p_rng,

                              unsigned char *output, size_t output_len,

                              const unsigned char *additional, size_t add_len )

{

    int ret = 0;

    mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *) p_rng;

    unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];

    unsigned char *p = output;

    unsigned char tmp[MBEDTLS_CTR_DRBG_BLOCKSIZE];

    int i;

    size_t use_len;

    if( output_len > MBEDTLS_CTR_DRBG_MAX_REQUEST )

        return( MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG );

    if( add_len > MBEDTLS_CTR_DRBG_MAX_INPUT )

        return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );

    memset( add_input, 0, MBEDTLS_CTR_DRBG_SEEDLEN );

    if( ctx->reseed_counter > ctx->reseed_interval ||

        ctx->prediction_resistance )

    {

        if( ( ret = mbedtls_ctr_drbg_reseed( ctx, additional, add_len ) ) != 0 )

        {

            return( ret );

        }

        add_len = 0;

    }

    if( add_len > 0 )

    {

        if( ( ret = block_cipher_df( add_input, additional, add_len ) ) != 0 )

            goto exit;

        if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )

            goto exit;

    }

    while( output_len > 0 )

    {

        /*

         * Increase counter

         */

        for( i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i-- )

            if( ++ctx->counter[i - 1] != 0 )

                break;

        /*

         * Crypt counter block

         */

        if( ( ret = mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, tmp ) ) != 0 )

            goto exit;

        use_len = ( output_len > MBEDTLS_CTR_DRBG_BLOCKSIZE ) ? MBEDTLS_CTR_DRBG_BLOCKSIZE :

                                                       output_len;

        /*

         * Copy random block to destination

         */

        memcpy( p, tmp, use_len );

        p += use_len;

        output_len -= use_len;

    }

    if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )

        goto exit;

    ctx->reseed_counter++;

exit:

    mbedtls_platform_zeroize( add_input, sizeof( add_input ) );

    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );

    return( ret );

}

int mbedtls_ctr_drbg_random( void *p_rng, unsigned char *output, size_t output_len )

{

    int ret;

    mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *) p_rng;

#if defined(MBEDTLS_THREADING_C)

    if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )

        return( ret );

#endif

    ret = mbedtls_ctr_drbg_random_with_add( ctx, output, output_len, NULL, 0 );

#if defined(MBEDTLS_THREADING_C)

    if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )

        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );

#endif

    return( ret );

}

#if defined(MBEDTLS_FS_IO)

int mbedtls_ctr_drbg_write_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path )

{

    int ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;

    FILE *f;

    unsigned char buf[ MBEDTLS_CTR_DRBG_MAX_INPUT ];

    if( ( f = fopen( path, "wb" ) ) == NULL )

        return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR );

    if( ( ret = mbedtls_ctr_drbg_random( ctx, buf, MBEDTLS_CTR_DRBG_MAX_INPUT ) ) != 0 )

        goto exit;

    if( fwrite( buf, 1, MBEDTLS_CTR_DRBG_MAX_INPUT, f ) != MBEDTLS_CTR_DRBG_MAX_INPUT )

        ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;

    else

        ret = 0;

exit:

    mbedtls_platform_zeroize( buf, sizeof( buf ) );

    fclose( f );

    return( ret );

}

int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path )

{

    int ret = 0;

    FILE *f = NULL;

    size_t n;

    unsigned char buf[ MBEDTLS_CTR_DRBG_MAX_INPUT ];

    unsigned char c;

    if( ( f = fopen( path, "rb" ) ) == NULL )

        return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR );

    n = fread( buf, 1, sizeof( buf ), f );

    if( fread( &c, 1, 1, f ) != 0 )

    {

        ret = MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG;

        goto exit;

    }

    if( n == 0 || ferror( f ) )

    {

        ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;

        goto exit;

    }

    fclose( f );

    f = NULL;

    ret = mbedtls_ctr_drbg_update_ret( ctx, buf, n );

exit:

    mbedtls_platform_zeroize( buf, sizeof( buf ) );

    if( f != NULL )

        fclose( f );

    if( ret != 0 )

        return( ret );

    return( mbedtls_ctr_drbg_write_seed_file( ctx, path ) );

}

#endif /* MBEDTLS_FS_IO */

#if defined(MBEDTLS_SELF_TEST)

static const unsigned char entropy_source_pr[96] =

    { 0xc1, 0x80, 0x81, 0xa6, 0x5d, 0x44, 0x02, 0x16,

      0x19, 0xb3, 0xf1, 0x80, 0xb1, 0xc9, 0x20, 0x02,

      0x6a, 0x54, 0x6f, 0x0c, 0x70, 0x81, 0x49, 0x8b,

      0x6e, 0xa6, 0x62, 0x52, 0x6d, 0x51, 0xb1, 0xcb,

      0x58, 0x3b, 0xfa, 0xd5, 0x37, 0x5f, 0xfb, 0xc9,

      0xff, 0x46, 0xd2, 0x19, 0xc7, 0x22, 0x3e, 0x95,

      0x45, 0x9d, 0x82, 0xe1, 0xe7, 0x22, 0x9f, 0x63,

      0x31, 0x69, 0xd2, 0x6b, 0x57, 0x47, 0x4f, 0xa3,

      0x37, 0xc9, 0x98, 0x1c, 0x0b, 0xfb, 0x91, 0x31,

      0x4d, 0x55, 0xb9, 0xe9, 0x1c, 0x5a, 0x5e, 0xe4,

      0x93, 0x92, 0xcf, 0xc5, 0x23, 0x12, 0xd5, 0x56,

      0x2c, 0x4a, 0x6e, 0xff, 0xdc, 0x10, 0xd0, 0x68 };

static const unsigned char entropy_source_nopr[64] =

    { 0x5a, 0x19, 0x4d, 0x5e, 0x2b, 0x31, 0x58, 0x14,

      0x54, 0xde, 0xf6, 0x75, 0xfb, 0x79, 0x58, 0xfe,

      0xc7, 0xdb, 0x87, 0x3e, 0x56, 0x89, 0xfc, 0x9d,

      0x03, 0x21, 0x7c, 0x68, 0xd8, 0x03, 0x38, 0x20,

      0xf9, 0xe6, 0x5e, 0x04, 0xd8, 0x56, 0xf3, 0xa9,

      0xc4, 0x4a, 0x4c, 0xbd, 0xc1, 0xd0, 0x08, 0x46,

      0xf5, 0x98, 0x3d, 0x77, 0x1c, 0x1b, 0x13, 0x7e,

      0x4e, 0x0f, 0x9d, 0x8e, 0xf4, 0x09, 0xf9, 0x2e };

static const unsigned char nonce_pers_pr[16] =

    { 0xd2, 0x54, 0xfc, 0xff, 0x02, 0x1e, 0x69, 0xd2,

      0x29, 0xc9, 0xcf, 0xad, 0x85, 0xfa, 0x48, 0x6c };

static const unsigned char nonce_pers_nopr[16] =

    { 0x1b, 0x54, 0xb8, 0xff, 0x06, 0x42, 0xbf, 0xf5,

      0x21, 0xf1, 0x5c, 0x1c, 0x0b, 0x66, 0x5f, 0x3f };

static const unsigned char result_pr[16] =

    { 0x34, 0x01, 0x16, 0x56, 0xb4, 0x29, 0x00, 0x8f,

      0x35, 0x63, 0xec, 0xb5, 0xf2, 0x59, 0x07, 0x23 };

static const unsigned char result_nopr[16] =

    { 0xa0, 0x54, 0x30, 0x3d, 0x8a, 0x7e, 0xa9, 0x88,

      0x9d, 0x90, 0x3e, 0x07, 0x7c, 0x6f, 0x21, 0x8f };

static size_t test_offset;

static int ctr_drbg_self_test_entropy( void *data, unsigned char *buf,

                                       size_t len )

{

    const unsigned char *p = data;

    memcpy( buf, p + test_offset, len );

    test_offset += len;

    return( 0 );

}

#define CHK( c )    if( (c) != 0 )                          \

                    {                                       \

                        if( verbose != 0 )                  \

                            mbedtls_printf( "failed\n" );  \

                        return( 1 );                        \

                    }

/*

 * Checkup routine

 */

int mbedtls_ctr_drbg_self_test( int verbose )

{

    mbedtls_ctr_drbg_context ctx;

    unsigned char buf[16];

    mbedtls_ctr_drbg_init( &ctx );

    /*

     * Based on a NIST CTR_DRBG test vector (PR = True)

     */

    if( verbose != 0 )

        mbedtls_printf( "  CTR_DRBG (PR = TRUE) : " );

    test_offset = 0;

    mbedtls_ctr_drbg_set_entropy_len( &ctx, 32 );

    CHK( mbedtls_ctr_drbg_seed( &ctx,

                                ctr_drbg_self_test_entropy,

                                (void *) entropy_source_pr,

                                nonce_pers_pr, 16 ) );

    mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );

    CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );

    CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );

    CHK( memcmp( buf, result_pr, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );

    mbedtls_ctr_drbg_free( &ctx );

    if( verbose != 0 )

        mbedtls_printf( "passed\n" );

    /*

     * Based on a NIST CTR_DRBG test vector (PR = FALSE)

     */

    if( verbose != 0 )

        mbedtls_printf( "  CTR_DRBG (PR = FALSE): " );

    mbedtls_ctr_drbg_init( &ctx );

    test_offset = 0;

    mbedtls_ctr_drbg_set_entropy_len( &ctx, 32 );

    CHK( mbedtls_ctr_drbg_seed( &ctx,

                                ctr_drbg_self_test_entropy,

                                (void *) entropy_source_nopr,

                                nonce_pers_nopr, 16 ) );

    CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) );

    CHK( mbedtls_ctr_drbg_reseed( &ctx, NULL, 0 ) );

    CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) );

    CHK( memcmp( buf, result_nopr, 16 ) );

    mbedtls_ctr_drbg_free( &ctx );

    if( verbose != 0 )

        mbedtls_printf( "passed\n" );

    if( verbose != 0 )

            mbedtls_printf( "\n" );

    return( 0 );

}

#endif /* MBEDTLS_SELF_TEST */

#endif /* MBEDTLS_CTR_DRBG_C */