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Entropy collector and CTR-DRBG now also work on SHA-256 if SHA-512 not available

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This commit is contained in:
Paul Bakker
2013-08-27 15:06:26 +02:00
parent 0a20171d52
commit fb08fd2e23
6 changed files with 65 additions and 5 deletions
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30
library/entropy.c
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@ -40,7 +40,11 @@ void entropy_init( entropy_context *ctx )
{
memset( ctx, 0, sizeof(entropy_context) );
#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
@ -91,8 +95,11 @@ static int entropy_update( entropy_context *ctx, unsigned char source_id,
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;
}
@ -100,8 +107,13 @@ static int entropy_update( entropy_context *ctx, unsigned char source_id,
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 );
}
@ -179,6 +191,7 @@ int entropy_func( void *data, unsigned char *output, size_t len )
memset( buf, 0, ENTROPY_BLOCK_SIZE );
#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_finish( &ctx->accumulator, buf );
/*
@ -192,6 +205,21 @@ int entropy_func( void *data, unsigned char *output, size_t len )
memset( &ctx->accumulator, 0, sizeof( sha512_context ) );
sha512_starts( &ctx->accumulator, 0 );
sha512_update( &ctx->accumulator, buf, ENTROPY_BLOCK_SIZE );
#else /* POLARSSL_ENTROPY_SHA512_ACCUMULATOR */
sha256_finish( &ctx->accumulator, buf );
/*
* Perform second SHA-256 on entropy
*/
sha256( buf, ENTROPY_BLOCK_SIZE, buf, 0 );
/*
* 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 );
#endif /* POLARSSL_ENTROPY_SHA512_ACCUMULATOR */
for( i = 0; i < ctx->source_count; i++ )
ctx->source[i].size = 0;