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Make all hash checking in programs constant-time

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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/aes/aescrypt2.c
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@ -75,6 +75,7 @@ int main( int argc, char *argv[] )
unsigned char key[512];
unsigned char digest[32];
unsigned char buffer[1024];
unsigned char diff;
aes_context aes_ctx;
sha256_context sha_ctx;
@ -397,7 +398,12 @@ int main( int argc, char *argv[] )
goto exit;
}
if( memcmp( digest, buffer, 32 ) != 0 )
/* Use constant-time buffer comparison */
diff = 0;
for( i = 0; i < 32; i++ )
diff |= digest[i] ^ buffer[i];
if( diff != 0 )
{
fprintf( stderr, "HMAC check failed: wrong key, "
"or file corrupted.\n" );