Subversion Repositories Kolibri OS

/*

 *  Entropy accumulator implementation

 *

 *  Copyright (C) 2006-2016, 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)

 */

#if !defined(MBEDTLS_CONFIG_FILE)

#include "mbedtls/config.h"

#else

#include MBEDTLS_CONFIG_FILE

#endif

#if defined(MBEDTLS_ENTROPY_C)

#if defined(MBEDTLS_TEST_NULL_ENTROPY)

#warning "**** WARNING!  MBEDTLS_TEST_NULL_ENTROPY defined! "

#warning "**** THIS BUILD HAS NO DEFINED ENTROPY SOURCES "

#warning "**** THIS BUILD IS *NOT* SUITABLE FOR PRODUCTION USE "

#endif

#include "mbedtls/entropy.h"

#include "mbedtls/entropy_poll.h"

#include "mbedtls/platform_util.h"

#include 

#if defined(MBEDTLS_FS_IO)

#include 

#endif

#if defined(MBEDTLS_ENTROPY_NV_SEED)

#include "mbedtls/platform.h"

#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 */

#if defined(MBEDTLS_HAVEGE_C)

#include "mbedtls/havege.h"

#endif

#define ENTROPY_MAX_LOOP    256     /**< Maximum amount to loop before error */

void mbedtls_entropy_init( mbedtls_entropy_context *ctx )

{

    ctx->source_count = 0;

    memset( ctx->source, 0, sizeof( ctx->source ) );

#if defined(MBEDTLS_THREADING_C)

    mbedtls_mutex_init( &ctx->mutex );

#endif

    ctx->accumulator_started = 0;

#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)

    mbedtls_sha512_init( &ctx->accumulator );

#else

    mbedtls_sha256_init( &ctx->accumulator );

#endif

#if defined(MBEDTLS_HAVEGE_C)

    mbedtls_havege_init( &ctx->havege_data );

#endif

    /* Reminder: Update ENTROPY_HAVE_STRONG in the test files

     *           when adding more strong entropy sources here. */

    /* add KolibriOS entropy sources */

    mbedtls_entropy_add_source( ctx, mbedtls_sysfn_3_poll, NULL,

                                4, MBEDTLS_ENTROPY_SOURCE_WEAK );

    mbedtls_entropy_add_source( ctx, mbedtls_sysfn_26_9_poll, NULL,

                                4, MBEDTLS_ENTROPY_SOURCE_WEAK );

    mbedtls_entropy_add_source( ctx, mbedtls_sysfn_14_poll, NULL,

                                4, MBEDTLS_ENTROPY_SOURCE_WEAK );

    mbedtls_entropy_add_source( ctx, mbedtls_sysfn_18_4_poll, NULL,

                                4, MBEDTLS_ENTROPY_SOURCE_STRONG );

    mbedtls_entropy_add_source( ctx, mbedtls_sysfn_37_0_poll, NULL,

                                4, MBEDTLS_ENTROPY_SOURCE_WEAK );

    mbedtls_entropy_add_source( ctx, mbedtls_sysfn_66_3_poll, NULL,

                                4, MBEDTLS_ENTROPY_SOURCE_WEAK );

    mbedtls_entropy_add_source( ctx, mbedtls_sysfn_68_0_poll, NULL,

                                4, MBEDTLS_ENTROPY_SOURCE_STRONG );

#if defined(MBEDTLS_TEST_NULL_ENTROPY)

    mbedtls_entropy_add_source( ctx, mbedtls_null_entropy_poll, NULL,

                                1, MBEDTLS_ENTROPY_SOURCE_STRONG );

#endif

#if !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)

#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)

    mbedtls_entropy_add_source( ctx, mbedtls_platform_entropy_poll, NULL,

                                MBEDTLS_ENTROPY_MIN_PLATFORM,

                                MBEDTLS_ENTROPY_SOURCE_STRONG );

#endif

#if defined(MBEDTLS_TIMING_C)

    mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL,

                                MBEDTLS_ENTROPY_MIN_HARDCLOCK,

                                MBEDTLS_ENTROPY_SOURCE_WEAK );

#endif

#if defined(MBEDTLS_HAVEGE_C)

    mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data,

                                MBEDTLS_ENTROPY_MIN_HAVEGE,

                                MBEDTLS_ENTROPY_SOURCE_STRONG );

#endif

#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)

    mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL,

                                MBEDTLS_ENTROPY_MIN_HARDWARE,

                                MBEDTLS_ENTROPY_SOURCE_STRONG );

#endif

#if defined(MBEDTLS_ENTROPY_NV_SEED)

    mbedtls_entropy_add_source( ctx, mbedtls_nv_seed_poll, NULL,

                                MBEDTLS_ENTROPY_BLOCK_SIZE,

                                MBEDTLS_ENTROPY_SOURCE_STRONG );

    ctx->initial_entropy_run = 0;

#endif

#endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */

}

void mbedtls_entropy_free( mbedtls_entropy_context *ctx )

{

#if defined(MBEDTLS_HAVEGE_C)

    mbedtls_havege_free( &ctx->havege_data );

#endif

#if defined(MBEDTLS_THREADING_C)

    mbedtls_mutex_free( &ctx->mutex );

#endif

#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)

    mbedtls_sha512_free( &ctx->accumulator );

#else

    mbedtls_sha256_free( &ctx->accumulator );

#endif

#if defined(MBEDTLS_ENTROPY_NV_SEED)

    ctx->initial_entropy_run = 0;

#endif

    ctx->source_count = 0;

    mbedtls_platform_zeroize( ctx->source, sizeof( ctx->source ) );

    ctx->accumulator_started = 0;

}

int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,

                        mbedtls_entropy_f_source_ptr f_source, void *p_source,

                        size_t threshold, int strong )

{

    int idx, ret = 0;

#if defined(MBEDTLS_THREADING_C)

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

        return( ret );

#endif

    idx = ctx->source_count;

    if( idx >= MBEDTLS_ENTROPY_MAX_SOURCES )

    {

        ret = MBEDTLS_ERR_ENTROPY_MAX_SOURCES;

        goto exit;

    }

    ctx->source[idx].f_source  = f_source;

    ctx->source[idx].p_source  = p_source;

    ctx->source[idx].threshold = threshold;

    ctx->source[idx].strong    = strong;

    ctx->source_count++;

exit:

#if defined(MBEDTLS_THREADING_C)

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

        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );

#endif

    return( ret );

}

/*

 * Entropy accumulator update

 */

static int entropy_update( mbedtls_entropy_context *ctx, unsigned char source_id,

                           const unsigned char *data, size_t len )

{

    unsigned char header[2];

    unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE];

    size_t use_len = len;

    const unsigned char *p = data;

    int ret = 0;

    if( use_len > MBEDTLS_ENTROPY_BLOCK_SIZE )

    {

#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)

        if( ( ret = mbedtls_sha512_ret( data, len, tmp, 0 ) ) != 0 )

            goto cleanup;

#else

        if( ( ret = mbedtls_sha256_ret( data, len, tmp, 0 ) ) != 0 )

            goto cleanup;

#endif

        p = tmp;

        use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;

    }

    header[0] = source_id;

    header[1] = use_len & 0xFF;

    /*

     * Start the accumulator if this has not already happened. Note that

     * it is sufficient to start the accumulator here only because all calls to

     * gather entropy eventually execute this code.

     */

#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)

    if( ctx->accumulator_started == 0 &&

        ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 )

        goto cleanup;

    else

        ctx->accumulator_started = 1;

    if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, header, 2 ) ) != 0 )

        goto cleanup;

    ret = mbedtls_sha512_update_ret( &ctx->accumulator, p, use_len );

#else

    if( ctx->accumulator_started == 0 &&

        ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 )

        goto cleanup;

    else

        ctx->accumulator_started = 1;

    if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, header, 2 ) ) != 0 )

        goto cleanup;

    ret = mbedtls_sha256_update_ret( &ctx->accumulator, p, use_len );

#endif

cleanup:

    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );

    return( ret );

}

int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,

                           const unsigned char *data, size_t len )

{

    int ret;

#if defined(MBEDTLS_THREADING_C)

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

        return( ret );

#endif

    ret = entropy_update( ctx, MBEDTLS_ENTROPY_SOURCE_MANUAL, data, len );

#if defined(MBEDTLS_THREADING_C)

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

        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );

#endif

    return( ret );

}

/*

 * Run through the different sources to add entropy to our accumulator

 */

static int entropy_gather_internal( mbedtls_entropy_context *ctx )

{

    int ret, i, have_one_strong = 0;

    unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER];

    size_t olen;

    if( ctx->source_count == 0 )

        return( MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED );

    /*

     * Run through our entropy sources

     */

    for( i = 0; i < ctx->source_count; i++ )

    {

        if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )

            have_one_strong = 1;

        olen = 0;

        if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source,

                        buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 )

        {

            goto cleanup;

        }

        /*

         * Add if we actually gathered something

         */

        if( olen > 0 )

        {

            if( ( ret = entropy_update( ctx, (unsigned char) i,

                                        buf, olen ) ) != 0 )

                return( ret );

            ctx->source[i].size += olen;

        }

    }

    if( have_one_strong == 0 )

        ret = MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE;

cleanup:

    mbedtls_platform_zeroize( buf, sizeof( buf ) );

    return( ret );

}

/*

 * Thread-safe wrapper for entropy_gather_internal()

 */

int mbedtls_entropy_gather( mbedtls_entropy_context *ctx )

{

    int ret;

#if defined(MBEDTLS_THREADING_C)

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

        return( ret );

#endif

    ret = entropy_gather_internal( ctx );

#if defined(MBEDTLS_THREADING_C)

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

        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );

#endif

    return( ret );

}

int mbedtls_entropy_func( void *data, unsigned char *output, size_t len )

{

    int ret, count = 0, i, done;

    mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data;

    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];

    if( len > MBEDTLS_ENTROPY_BLOCK_SIZE )

        return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );

#if defined(MBEDTLS_ENTROPY_NV_SEED)

    /* Update the NV entropy seed before generating any entropy for outside

     * use.

     */

    if( ctx->initial_entropy_run == 0 )

    {

        ctx->initial_entropy_run = 1;

        if( ( ret = mbedtls_entropy_update_nv_seed( ctx ) ) != 0 )

            return( ret );

    }

#endif

#if defined(MBEDTLS_THREADING_C)

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

        return( ret );

#endif

    /*

     * Always gather extra entropy before a call

     */

    do

    {

        if( count++ > ENTROPY_MAX_LOOP )

        {

            /*for( i = 0; i < ctx->source_count; i++ ) { // rgimad

                mbedtls_printf("ctx->source[%d].size = %d\n", i, ctx->source[i].size);

            }*/

            ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

            goto exit;

        }

        if( ( ret = entropy_gather_internal( ctx ) ) != 0 )

            goto exit;

        done = 1;

        for( i = 0; i < ctx->source_count; i++ )

            if( ctx->source[i].size < ctx->source[i].threshold )

                done = 0;

    }

    while( ! done );

    memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );

#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)

    /*

     * Note that at this stage it is assumed that the accumulator was started

     * in a previous call to entropy_update(). If this is not guaranteed, the

     * code below will fail.

     */

    if( ( ret = mbedtls_sha512_finish_ret( &ctx->accumulator, buf ) ) != 0 )

        goto exit;

    /*

     * Reset accumulator and counters and recycle existing entropy

     */

    mbedtls_sha512_free( &ctx->accumulator );

    mbedtls_sha512_init( &ctx->accumulator );

    if( ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 )

        goto exit;

    if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, buf,

                                           MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )

        goto exit;

    /*

     * Perform second SHA-512 on entropy

     */

    if( ( ret = mbedtls_sha512_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE,

                                    buf, 0 ) ) != 0 )

        goto exit;

#else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */

    if( ( ret = mbedtls_sha256_finish_ret( &ctx->accumulator, buf ) ) != 0 )

        goto exit;

    /*

     * Reset accumulator and counters and recycle existing entropy

     */

    mbedtls_sha256_free( &ctx->accumulator );

    mbedtls_sha256_init( &ctx->accumulator );

    if( ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 )

        goto exit;

    if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, buf,

                                           MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )

        goto exit;

    /*

     * Perform second SHA-256 on entropy

     */

    if( ( ret = mbedtls_sha256_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE,

                                    buf, 0 ) ) != 0 )

        goto exit;

#endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */

    for( i = 0; i < ctx->source_count; i++ )

        ctx->source[i].size = 0;

    memcpy( output, buf, len );

    ret = 0;

exit:

    mbedtls_platform_zeroize( buf, sizeof( buf ) );

#if defined(MBEDTLS_THREADING_C)

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

        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );

#endif

    return( ret );

}

#if defined(MBEDTLS_ENTROPY_NV_SEED)

int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx )

{

    int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;

    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];

    /* Read new seed  and write it to NV */

    if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )

        return( ret );

    if( mbedtls_nv_seed_write( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )

        return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );

    /* Manually update the remaining stream with a separator value to diverge */

    memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );

    ret = mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );

    return( ret );

}

#endif /* MBEDTLS_ENTROPY_NV_SEED */

#if defined(MBEDTLS_FS_IO)

int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path )

{

    int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;

    FILE *f;

    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];

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

        return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );

    if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )

        goto exit;

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

    {

        ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;

        goto exit;

    }

    ret = 0;

exit:

    mbedtls_platform_zeroize( buf, sizeof( buf ) );

    fclose( f );

    return( ret );

}

int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path )

{

    int ret = 0;

    FILE *f;

    size_t n;

    unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];

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

        return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );

    fseek( f, 0, SEEK_END );

    n = (size_t) ftell( f );

    fseek( f, 0, SEEK_SET );

    if( n > MBEDTLS_ENTROPY_MAX_SEED_SIZE )

        n = MBEDTLS_ENTROPY_MAX_SEED_SIZE;

    if( fread( buf, 1, n, f ) != n )

        ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;

    else

        ret = mbedtls_entropy_update_manual( ctx, buf, n );

    fclose( f );

    mbedtls_platform_zeroize( buf, sizeof( buf ) );

    if( ret != 0 )

        return( ret );

    return( mbedtls_entropy_write_seed_file( ctx, path ) );

}

#endif /* MBEDTLS_FS_IO */

#if defined(MBEDTLS_SELF_TEST)

#if !defined(MBEDTLS_TEST_NULL_ENTROPY)

/*

 * Dummy source function

 */

static int entropy_dummy_source( void *data, unsigned char *output,

                                 size_t len, size_t *olen )

{

    ((void) data);

    memset( output, 0x2a, len );

    *olen = len;

    return( 0 );

}

#endif /* !MBEDTLS_TEST_NULL_ENTROPY */

#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)

static int mbedtls_entropy_source_self_test_gather( unsigned char *buf, size_t buf_len )

{

    int ret = 0;

    size_t entropy_len = 0;

    size_t olen = 0;

    size_t attempts = buf_len;

    while( attempts > 0 && entropy_len < buf_len )

    {

        if( ( ret = mbedtls_hardware_poll( NULL, buf + entropy_len,

            buf_len - entropy_len, &olen ) ) != 0 )

            return( ret );

        entropy_len += olen;

        attempts--;

    }

    if( entropy_len < buf_len )

    {

        ret = 1;

    }

    return( ret );

}

static int mbedtls_entropy_source_self_test_check_bits( const unsigned char *buf,

                                                        size_t buf_len )

{

    unsigned char set= 0xFF;

    unsigned char unset = 0x00;

    size_t i;

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

    {

        set &= buf[i];

        unset |= buf[i];

    }

    return( set == 0xFF || unset == 0x00 );

}

/*

 * A test to ensure hat the entropy sources are functioning correctly

 * and there is no obvious failure. The test performs the following checks:

 *  - The entropy source is not providing only 0s (all bits unset) or 1s (all

 *    bits set).

 *  - The entropy source is not providing values in a pattern. Because the

 *    hardware could be providing data in an arbitrary length, this check polls

 *    the hardware entropy source twice and compares the result to ensure they

 *    are not equal.

 *  - The error code returned by the entropy source is not an error.

 */

int mbedtls_entropy_source_self_test( int verbose )

{

    int ret = 0;

    unsigned char buf0[2 * sizeof( unsigned long long int )];

    unsigned char buf1[2 * sizeof( unsigned long long int )];

    if( verbose != 0 )

        mbedtls_printf( "  ENTROPY_BIAS test: " );

    memset( buf0, 0x00, sizeof( buf0 ) );

    memset( buf1, 0x00, sizeof( buf1 ) );

    if( ( ret = mbedtls_entropy_source_self_test_gather( buf0, sizeof( buf0 ) ) ) != 0 )

        goto cleanup;

    if( ( ret = mbedtls_entropy_source_self_test_gather( buf1, sizeof( buf1 ) ) ) != 0 )

        goto cleanup;

    /* Make sure that the returned values are not all 0 or 1 */

    if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf0, sizeof( buf0 ) ) ) != 0 )

        goto cleanup;

    if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf1, sizeof( buf1 ) ) ) != 0 )

        goto cleanup;

    /* Make sure that the entropy source is not returning values in a

     * pattern */

    ret = memcmp( buf0, buf1, sizeof( buf0 ) ) == 0;

cleanup:

    if( verbose != 0 )

    {

        if( ret != 0 )

            mbedtls_printf( "failed\n" );

        else

            mbedtls_printf( "passed\n" );

        mbedtls_printf( "\n" );

    }

    return( ret != 0 );

}

#endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */

/*

 * The actual entropy quality is hard to test, but we can at least

 * test that the functions don't cause errors and write the correct

 * amount of data to buffers.

 */

int mbedtls_entropy_self_test( int verbose )

{

    int ret = 1;

#if !defined(MBEDTLS_TEST_NULL_ENTROPY)

    mbedtls_entropy_context ctx;

    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };

    unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };

    size_t i, j;

#endif /* !MBEDTLS_TEST_NULL_ENTROPY */

    if( verbose != 0 )

        mbedtls_printf( "  ENTROPY test: " );

#if !defined(MBEDTLS_TEST_NULL_ENTROPY)

    mbedtls_entropy_init( &ctx );

    /* First do a gather to make sure we have default sources */

    if( ( ret = mbedtls_entropy_gather( &ctx ) ) != 0 )

        goto cleanup;

    ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16,

                                      MBEDTLS_ENTROPY_SOURCE_WEAK );

    if( ret != 0 )

        goto cleanup;

    if( ( ret = mbedtls_entropy_update_manual( &ctx, buf, sizeof buf ) ) != 0 )

        goto cleanup;

    /*

     * To test that mbedtls_entropy_func writes correct number of bytes:

     * - use the whole buffer and rely on ASan to detect overruns

     * - collect entropy 8 times and OR the result in an accumulator:

     *   any byte should then be 0 with probably 2^(-64), so requiring

     *   each of the 32 or 64 bytes to be non-zero has a false failure rate

     *   of at most 2^(-58) which is acceptable.

     */

    for( i = 0; i < 8; i++ )

    {

        if( ( ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ) ) != 0 )

            goto cleanup;

        for( j = 0; j < sizeof( buf ); j++ )

            acc[j] |= buf[j];

    }

    for( j = 0; j < sizeof( buf ); j++ )

    {

        if( acc[j] == 0 )

        {

            ret = 1;

            goto cleanup;

        }

    }

#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)

    if( ( ret = mbedtls_entropy_source_self_test( 0 ) ) != 0 )

        goto cleanup;

#endif

cleanup:

    mbedtls_entropy_free( &ctx );

#endif /* !MBEDTLS_TEST_NULL_ENTROPY */

    if( verbose != 0 )

    {

        if( ret != 0 )

            mbedtls_printf( "failed\n" );

        else

            mbedtls_printf( "passed\n" );

        mbedtls_printf( "\n" );

    }

    return( ret != 0 );

}

#endif /* MBEDTLS_SELF_TEST */

#endif /* MBEDTLS_ENTROPY_C */