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Make all hash checking in programs constant-time

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This commit is contained in:
Manuel Pégourié-Gonnard
2013-10-28 12:51:32 +01:00
committed by Paul Bakker
parent 424cd6943c
commit 291f9af935
5 changed files with 35 additions and 5 deletions
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8
programs/hash/generic_sum.c
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@@ -77,6 +77,7 @@ static int generic_check( const md_info_t *md_info, char *filename )
int nb_tot1, nb_tot2;
unsigned char sum[POLARSSL_MD_MAX_SIZE];
char buf[POLARSSL_MD_MAX_SIZE * 2 + 1], line[1024];
char diff;
if( ( f = fopen( filename, "rb" ) ) == NULL )
{
@@ -123,7 +124,12 @@ static int generic_check( const md_info_t *md_info, char *filename )
for( i = 0; i < md_info->size; i++ )
sprintf( buf + i * 2, "%02x", sum[i] );
if( memcmp( line, buf, 2 * md_info->size ) != 0 )
/* Use constant-time buffer comparison */
diff = 0;
for( i = 0; i < 2 * md_info->size; i++ )
diff |= line[i] ^ buf[i];
if( diff != 0 )
{
nb_err2++;
fprintf( stderr, "wrong checksum: %s\n", line + 66 );