Reliably zeroize sensitive data in Crypt-and-Hash sample application
The AES sample application programs/aes/crypt_and_hash could miss
zeroizing the stack-based key buffer in case of an error during
operation. This commit fixes this and also clears all command line
arguments (one of which might be the key) before exit.
diff --git a/programs/aes/crypt_and_hash.c b/programs/aes/crypt_and_hash.c
index adb95e0..a16e91e 100644
--- a/programs/aes/crypt_and_hash.c
+++ b/programs/aes/crypt_and_hash.c
@@ -224,8 +224,6 @@
}
}
- memset( argv[6], 0, strlen( argv[6] ) );
-
#if defined(_WIN32_WCE)
filesize = fseek( fin, 0L, SEEK_END );
#else
@@ -303,8 +301,6 @@
}
- memset( key, 0, sizeof( key ) );
-
if( mbedtls_cipher_setkey( &cipher_ctx, digest, cipher_info->key_bitlen,
MBEDTLS_ENCRYPT ) != 0 )
{
@@ -444,8 +440,6 @@
mbedtls_md_finish( &md_ctx, digest );
}
- memset( key, 0, sizeof( key ) );
-
if( mbedtls_cipher_setkey( &cipher_ctx, digest, cipher_info->key_bitlen,
MBEDTLS_DECRYPT ) != 0 )
{
@@ -540,7 +534,16 @@
if( fout )
fclose( fout );
+ /* Zeroize all command line arguments to also cover
+ the case when the user has missed or reordered some,
+ in which case the key might not be in argv[6]. */
+ for( i = 0; i < argc; i++ )
+ memset( argv[i], 0, strlen( argv[i] ) );
+
+ memset( IV, 0, sizeof( IV ) );
+ memset( key, 0, sizeof( key ) );
memset( buffer, 0, sizeof( buffer ) );
+ memset( output, 0, sizeof( output ) );
memset( digest, 0, sizeof( digest ) );
mbedtls_cipher_free( &cipher_ctx );