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dolphin/Externals/polarssl/library/entropy.c

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/*
* Entropy accumulator implementation
*
* Copyright (C) 2006-2014, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* 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.
*/
#if !defined(POLARSSL_CONFIG_FILE)
#include "polarssl/config.h"
#else
#include POLARSSL_CONFIG_FILE
#endif
#if defined(POLARSSL_ENTROPY_C)
#include "polarssl/entropy.h"
#include "polarssl/entropy_poll.h"
#if defined(POLARSSL_FS_IO)
#include <stdio.h>
#endif
#if defined(POLARSSL_HAVEGE_C)
#include "polarssl/havege.h"
#endif
/* Implementation that should never be optimized out by the compiler */
static void polarssl_zeroize( void *v, size_t n ) {
volatile unsigned char *p = v; while( n-- ) *p++ = 0;
}
#define ENTROPY_MAX_LOOP 256 /**< Maximum amount to loop before error */
void entropy_init( entropy_context *ctx )
{
memset( ctx, 0, sizeof(entropy_context) );
#if defined(POLARSSL_THREADING_C)
polarssl_mutex_init( &ctx->mutex );
#endif
#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_starts( &ctx->accumulator, 0 );
#else
sha256_starts( &ctx->accumulator, 0 );
#endif
#if defined(POLARSSL_HAVEGE_C)
havege_init( &ctx->havege_data );
#endif
#if !defined(POLARSSL_NO_DEFAULT_ENTROPY_SOURCES)
#if !defined(POLARSSL_NO_PLATFORM_ENTROPY)
entropy_add_source( ctx, platform_entropy_poll, NULL,
ENTROPY_MIN_PLATFORM );
#endif
#if defined(POLARSSL_TIMING_C)
entropy_add_source( ctx, hardclock_poll, NULL, ENTROPY_MIN_HARDCLOCK );
#endif
#if defined(POLARSSL_HAVEGE_C)
entropy_add_source( ctx, havege_poll, &ctx->havege_data,
ENTROPY_MIN_HAVEGE );
#endif
#endif /* POLARSSL_NO_DEFAULT_ENTROPY_SOURCES */
}
void entropy_free( entropy_context *ctx )
{
#if defined(POLARSSL_HAVEGE_C)
havege_free( &ctx->havege_data );
#endif
polarssl_zeroize( ctx, sizeof( entropy_context ) );
#if defined(POLARSSL_THREADING_C)
polarssl_mutex_free( &ctx->mutex );
#endif
}
int entropy_add_source( entropy_context *ctx,
f_source_ptr f_source, void *p_source,
size_t threshold )
{
int index, ret = 0;
#if defined(POLARSSL_THREADING_C)
if( ( ret = polarssl_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#endif
index = ctx->source_count;
if( index >= ENTROPY_MAX_SOURCES )
{
ret = POLARSSL_ERR_ENTROPY_MAX_SOURCES;
goto exit;
}
ctx->source[index].f_source = f_source;
ctx->source[index].p_source = p_source;
ctx->source[index].threshold = threshold;
ctx->source_count++;
exit:
#if defined(POLARSSL_THREADING_C)
if( polarssl_mutex_unlock( &ctx->mutex ) != 0 )
return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
#endif
return( ret );
}
/*
* Entropy accumulator update
*/
static int entropy_update( entropy_context *ctx, unsigned char source_id,
const unsigned char *data, size_t len )
{
unsigned char header[2];
unsigned char tmp[ENTROPY_BLOCK_SIZE];
size_t use_len = len;
const unsigned char *p = data;
if( use_len > ENTROPY_BLOCK_SIZE )
{
#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512( data, len, tmp, 0 );
#else
sha256( data, len, tmp, 0 );
#endif
p = tmp;
use_len = ENTROPY_BLOCK_SIZE;
}
header[0] = source_id;
header[1] = use_len & 0xFF;
#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_update( &ctx->accumulator, header, 2 );
sha512_update( &ctx->accumulator, p, use_len );
#else
sha256_update( &ctx->accumulator, header, 2 );
sha256_update( &ctx->accumulator, p, use_len );
#endif
return( 0 );
}
int entropy_update_manual( entropy_context *ctx,
const unsigned char *data, size_t len )
{
int ret;
#if defined(POLARSSL_THREADING_C)
if( ( ret = polarssl_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#endif
ret = entropy_update( ctx, ENTROPY_SOURCE_MANUAL, data, len );
#if defined(POLARSSL_THREADING_C)
if( polarssl_mutex_unlock( &ctx->mutex ) != 0 )
return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
#endif
return( ret );
}
/*
* Run through the different sources to add entropy to our accumulator
*/
static int entropy_gather_internal( entropy_context *ctx )
{
int ret, i;
unsigned char buf[ENTROPY_MAX_GATHER];
size_t olen;
if( ctx->source_count == 0 )
return( POLARSSL_ERR_ENTROPY_NO_SOURCES_DEFINED );
/*
* Run through our entropy sources
*/
for( i = 0; i < ctx->source_count; i++ )
{
olen = 0;
if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source,
buf, ENTROPY_MAX_GATHER, &olen ) ) != 0 )
{
return( ret );
}
/*
* Add if we actually gathered something
*/
if( olen > 0 )
{
entropy_update( ctx, (unsigned char) i, buf, olen );
ctx->source[i].size += olen;
}
}
return( 0 );
}
/*
* Thread-safe wrapper for entropy_gather_internal()
*/
int entropy_gather( entropy_context *ctx )
{
int ret;
#if defined(POLARSSL_THREADING_C)
if( ( ret = polarssl_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#endif
ret = entropy_gather_internal( ctx );
#if defined(POLARSSL_THREADING_C)
if( polarssl_mutex_unlock( &ctx->mutex ) != 0 )
return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
#endif
return( ret );
}
int entropy_func( void *data, unsigned char *output, size_t len )
{
int ret, count = 0, i, reached;
entropy_context *ctx = (entropy_context *) data;
unsigned char buf[ENTROPY_BLOCK_SIZE];
if( len > ENTROPY_BLOCK_SIZE )
return( POLARSSL_ERR_ENTROPY_SOURCE_FAILED );
#if defined(POLARSSL_THREADING_C)
if( ( ret = polarssl_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#endif
/*
* Always gather extra entropy before a call
*/
do
{
if( count++ > ENTROPY_MAX_LOOP )
{
ret = POLARSSL_ERR_ENTROPY_SOURCE_FAILED;
goto exit;
}
if( ( ret = entropy_gather_internal( ctx ) ) != 0 )
goto exit;
reached = 0;
for( i = 0; i < ctx->source_count; i++ )
if( ctx->source[i].size >= ctx->source[i].threshold )
reached++;
}
while( reached != ctx->source_count );
memset( buf, 0, ENTROPY_BLOCK_SIZE );
#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_finish( &ctx->accumulator, buf );
/*
* Reset accumulator and counters and recycle existing entropy
*/
memset( &ctx->accumulator, 0, sizeof( sha512_context ) );
sha512_starts( &ctx->accumulator, 0 );
sha512_update( &ctx->accumulator, buf, ENTROPY_BLOCK_SIZE );
/*
* Perform second SHA-512 on entropy
*/
sha512( buf, ENTROPY_BLOCK_SIZE, buf, 0 );
#else /* POLARSSL_ENTROPY_SHA512_ACCUMULATOR */
sha256_finish( &ctx->accumulator, buf );
/*
* Reset accumulator and counters and recycle existing entropy
*/
memset( &ctx->accumulator, 0, sizeof( sha256_context ) );
sha256_starts( &ctx->accumulator, 0 );
sha256_update( &ctx->accumulator, buf, ENTROPY_BLOCK_SIZE );
/*
* Perform second SHA-256 on entropy
*/
sha256( buf, ENTROPY_BLOCK_SIZE, buf, 0 );
#endif /* POLARSSL_ENTROPY_SHA512_ACCUMULATOR */
for( i = 0; i < ctx->source_count; i++ )
ctx->source[i].size = 0;
memcpy( output, buf, len );
ret = 0;
exit:
#if defined(POLARSSL_THREADING_C)
if( polarssl_mutex_unlock( &ctx->mutex ) != 0 )
return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
#endif
return( ret );
}
#if defined(POLARSSL_FS_IO)
int entropy_write_seed_file( entropy_context *ctx, const char *path )
{
int ret = POLARSSL_ERR_ENTROPY_FILE_IO_ERROR;
FILE *f;
unsigned char buf[ENTROPY_BLOCK_SIZE];
if( ( f = fopen( path, "wb" ) ) == NULL )
return( POLARSSL_ERR_ENTROPY_FILE_IO_ERROR );
if( ( ret = entropy_func( ctx, buf, ENTROPY_BLOCK_SIZE ) ) != 0 )
goto exit;
if( fwrite( buf, 1, ENTROPY_BLOCK_SIZE, f ) != ENTROPY_BLOCK_SIZE )
{
ret = POLARSSL_ERR_ENTROPY_FILE_IO_ERROR;
goto exit;
}
ret = 0;
exit:
fclose( f );
return( ret );
}
int entropy_update_seed_file( entropy_context *ctx, const char *path )
{
FILE *f;
size_t n;
unsigned char buf[ ENTROPY_MAX_SEED_SIZE ];
if( ( f = fopen( path, "rb" ) ) == NULL )
return( POLARSSL_ERR_ENTROPY_FILE_IO_ERROR );
fseek( f, 0, SEEK_END );
n = (size_t) ftell( f );
fseek( f, 0, SEEK_SET );
if( n > ENTROPY_MAX_SEED_SIZE )
n = ENTROPY_MAX_SEED_SIZE;
if( fread( buf, 1, n, f ) != n )
{
fclose( f );
return( POLARSSL_ERR_ENTROPY_FILE_IO_ERROR );
}
fclose( f );
entropy_update_manual( ctx, buf, n );
return( entropy_write_seed_file( ctx, path ) );
}
#endif /* POLARSSL_FS_IO */
#if defined(POLARSSL_SELF_TEST)
#if defined(POLARSSL_PLATFORM_C)
#include "polarssl/platform.h"
#else
#include <stdio.h>
#define polarssl_printf printf
#endif
/*
* 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 );
}
/*
* 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 entropy_self_test( int verbose )
{
int ret = 0;
entropy_context ctx;
unsigned char buf[ENTROPY_BLOCK_SIZE] = { 0 };
unsigned char acc[ENTROPY_BLOCK_SIZE] = { 0 };
size_t i, j;
if( verbose != 0 )
polarssl_printf( " ENTROPY test: " );
entropy_init( &ctx );
ret = entropy_add_source( &ctx, entropy_dummy_source, NULL, 16 );
if( ret != 0 )
goto cleanup;
if( ( ret = entropy_gather( &ctx ) ) != 0 )
goto cleanup;
if( ( ret = entropy_update_manual( &ctx, buf, sizeof buf ) ) != 0 )
goto cleanup;
/*
* To test that 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 = 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;
}
}
cleanup:
entropy_free( &ctx );
if( verbose != 0 )
{
if( ret != 0 )
polarssl_printf( "failed\n" );
else
polarssl_printf( "passed\n" );
polarssl_printf( "\n" );
}
return( ret != 0 );
}
#endif /* POLARSSL_SELF_TEST */
#endif /* POLARSSL_ENTROPY_C */
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