Use mbedtls_xor in AES
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/aes.c b/library/aes.c
index 7d03524..4f7c888 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -978,7 +978,6 @@
const unsigned char *input,
unsigned char *output )
{
- int i;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char temp[16];
@@ -1009,8 +1008,7 @@
if( ret != 0 )
goto exit;
- for( i = 0; i < 16; i++ )
- output[i] = (unsigned char)( output[i] ^ iv[i] );
+ mbedtls_xor( output, output, iv, 16 );
memcpy( iv, temp, 16 );
@@ -1023,8 +1021,7 @@
{
while( length > 0 )
{
- for( i = 0; i < 16; i++ )
- output[i] = (unsigned char)( input[i] ^ iv[i] );
+ mbedtls_xor( output, input, iv, 16 );
ret = mbedtls_aes_crypt_ecb( ctx, mode, output, output );
if( ret != 0 )
@@ -1106,8 +1103,6 @@
while( blocks-- )
{
- size_t i;
-
if( leftover && ( mode == MBEDTLS_AES_DECRYPT ) && blocks == 0 )
{
/* We are on the last block in a decrypt operation that has
@@ -1119,15 +1114,13 @@
mbedtls_gf128mul_x_ble( tweak, tweak );
}
- for( i = 0; i < 16; i++ )
- tmp[i] = input[i] ^ tweak[i];
+ mbedtls_xor( tmp, input, tweak, 16 );
ret = mbedtls_aes_crypt_ecb( &ctx->crypt, mode, tmp, tmp );
if( ret != 0 )
return( ret );
- for( i = 0; i < 16; i++ )
- output[i] = tmp[i] ^ tweak[i];
+ mbedtls_xor( output, tmp, tweak, 16 );
/* Update the tweak for the next block. */
mbedtls_gf128mul_x_ble( tweak, tweak );
@@ -1147,20 +1140,19 @@
size_t i;
unsigned char *prev_output = output - 16;
- /* Copy ciphertext bytes from the previous block to our output for each
- * byte of ciphertext we won't steal. At the same time, copy the
- * remainder of the input for this final round (since the loop bounds
- * are the same). */
+ /* Copy the remainder of the input for this final round. */
for( i = 0; i < leftover; i++ )
{
output[i] = prev_output[i];
- tmp[i] = input[i] ^ t[i];
}
+ /* Copy ciphertext bytes from the previous block to our output for each
+ * byte of ciphertext we won't steal. */
+ mbedtls_xor( tmp, input, t, leftover );
+
/* Copy ciphertext bytes from the previous block for input in this
* round. */
- for( ; i < 16; i++ )
- tmp[i] = prev_output[i] ^ t[i];
+ mbedtls_xor( tmp + i, prev_output + i, t + i, 16 - i );
ret = mbedtls_aes_crypt_ecb( &ctx->crypt, mode, tmp, tmp );
if( ret != 0 )
@@ -1168,8 +1160,7 @@
/* Write the result back to the previous block, overriding the previous
* output we copied. */
- for( i = 0; i < 16; i++ )
- prev_output[i] = tmp[i] ^ t[i];
+ mbedtls_xor( prev_output, tmp, t, 16 );
}
return( 0 );