Make CCM shuffling and masking optional
Add a define for CCM shuffling and masking operations.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/library/ccm.c b/library/ccm.c
index dc176b2..5ba869a 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -114,6 +114,7 @@
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ccm_context ) );
}
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
/* Durstenfeld's version of Fisher-Yates shuffle */
static void mbedtls_generate_permutation( unsigned char* table, size_t size )
{
@@ -148,6 +149,7 @@
table[i] = mbedtls_platform_random_in_range( 256 );
}
}
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
/*
* Macros for common operations.
@@ -159,6 +161,7 @@
* (Always using b as the source helps the compiler optimise a bit better.)
* Initial b masking happens outside of this macro due to various sources of it.
*/
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
#define UPDATE_CBC_MAC \
for( i = 0; i < 16; i++ ) \
{ \
@@ -168,14 +171,25 @@
\
if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \
return( ret );
+#else
+#define UPDATE_CBC_MAC \
+ for( i = 0; i < 16; i++ ) \
+ y[i] ^= b[i]; \
+ \
+ if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \
+ return( ret );
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
/*
* Copy src to dst starting at a random offset, while masking the whole dst buffer.
*/
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
#define COPY_MASK( dst, src, mask, len_src, len_dst ) \
do \
{ \
unsigned j, offset = mbedtls_platform_random_in_range( 256 ); \
+ mbedtls_generate_masks( mask_table, 16 ); \
+ mbedtls_generate_permutation( perm_table, 16 ); \
for( i = 0; i < len_src; i++ ) \
{ \
j = (i + offset) % len_src; \
@@ -184,11 +198,14 @@
for( ; i < len_dst; i++ ) \
(dst)[i] ^= (mask)[i]; \
} while( 0 )
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
+
/*
* Encrypt or decrypt a partial block with CTR
* Warning: using b for temporary storage! src and dst must not be b!
* This avoids allocating one more 16 bytes buffer while allowing src == dst.
*/
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
#define CTR_CRYPT( dst, src, len ) \
do \
{ \
@@ -200,13 +217,27 @@
return( ret ); \
} \
\
- for( i = 0; i < len; i++ ) \
+ for( i = 0; i < (len); i++ ) \
{ \
(dst)[perm_table[i]] = (src)[perm_table[i]] ^ mask_table[perm_table[i]];\
(dst)[perm_table[i]] ^= b[perm_table[i]]; \
(dst)[perm_table[i]] ^= mask_table[perm_table[i]]; \
} \
} while( 0 )
+#else
+#define CTR_CRYPT( dst, src, len ) \
+ do \
+ { \
+ if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctr, \
+ 16, b, &olen ) ) != 0 ) \
+ { \
+ return( ret ); \
+ } \
+ \
+ for( i = 0; i < (len); i++ ) \
+ (dst)[i] = (src)[i] ^ b[i]; \
+ } while( 0 )
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
/*
* Authenticated encryption or decryption
@@ -224,12 +255,13 @@
unsigned char b[16];
unsigned char y[16];
unsigned char ctr[16];
- unsigned char perm_table[16];
- unsigned char mask_table[16];
const unsigned char *src;
unsigned char *dst;
volatile size_t flow_ctrl = 0;
-
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
+ unsigned char perm_table[16];
+ unsigned char mask_table[16];
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
/*
* Check length requirements: SP800-38C A.1
* Additional requirement: a < 2^16 - 2^8 to simplify the code.
@@ -266,6 +298,7 @@
* 5 .. 3 (t - 2) / 2
* 2 .. 0 q - 1
*/
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
mbedtls_generate_masks( mask_table, 16 );
mbedtls_generate_permutation( perm_table, 16 );
b[0] = (unsigned char) ( ( ( add_len > 0 ) << 6 ) |
@@ -279,11 +312,21 @@
}
for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
b[15-i] = (unsigned char)( ( len_left & 0xFF ) ) ^ mask_table[15-i];
+#else
+ b[0] = 0;
+ b[0] |= ( add_len > 0 ) << 6;
+ b[0] |= ( ( tag_len - 2 ) / 2 ) << 3;
+ b[0] |= q - 1;
+
+ mbedtls_platform_memcpy( b + 1, iv, iv_len );
+ flow_ctrl += iv_len; /* iv_len + 1 */
+ for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
+ b[15-i] = (unsigned char)( len_left & 0xFF );
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
if( len_left > 0 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
-
/* Start CBC-MAC with first block */
memset( y, 0, 16 );
UPDATE_CBC_MAC;
@@ -298,16 +341,20 @@
size_t use_len;
len_left = add_len;
src = add;
-
- mbedtls_generate_masks( mask_table, 16 );
- mbedtls_generate_permutation( perm_table, 16 );
mbedtls_platform_memset( b, 0, 16 );
- b[0] = (unsigned char)( ( ( add_len >> 8 ) & 0xFF ) ^ mask_table[0] );
- b[1] = (unsigned char)( ( ( add_len ) & 0xFF ) ^ mask_table[1] );
use_len = len_left < 16 - 2 ? len_left : 16 - 2;
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
COPY_MASK( b+2, src, mask_table+2, use_len, 14 );
+ b[0] = (unsigned char)( ( ( add_len >> 8 ) & 0xFF ) ^ mask_table[0] );
+ b[1] = (unsigned char)( ( ( add_len ) & 0xFF ) ^ mask_table[1] );
+#else
+ b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF );
+ b[1] = (unsigned char)( ( add_len ) & 0xFF );
+
+ mbedtls_platform_memcpy( b + 2, src, use_len );
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
len_left -= use_len;
src += use_len;
@@ -317,12 +364,14 @@
while( len_left > 0 )
{
- mbedtls_generate_masks( mask_table, 16 );
- mbedtls_generate_permutation( perm_table, 16 );
use_len = len_left > 16 ? 16 : len_left;
-
mbedtls_platform_memset( b, 0, 16 );
- COPY_MASK( b, src, mask_table, use_len, 16);
+
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
+ COPY_MASK( b, src, mask_table, use_len, 16 );
+#else
+ mbedtls_platform_memcpy( b, src, use_len );
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
UPDATE_CBC_MAC;
len_left -= use_len;
@@ -362,10 +411,13 @@
if( mode == CCM_ENCRYPT )
{
- mbedtls_generate_masks( mask_table, 16 );
- mbedtls_generate_permutation( perm_table, 16 );
mbedtls_platform_memset( b, 0, 16 );
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
COPY_MASK( b, src, mask_table, use_len, 16 );
+#else
+ mbedtls_platform_memcpy( b, src, use_len );
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
+
UPDATE_CBC_MAC;
flow_ctrl++; /* iv_len + 3 + ( add_len? 1 : 0 ) + encryptions */
}
@@ -374,10 +426,12 @@
if( mode == CCM_DECRYPT )
{
- mbedtls_generate_masks( mask_table, 16 );
- mbedtls_generate_permutation( perm_table, 16 );
mbedtls_platform_memset( b, 0, 16 );
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
COPY_MASK( b, dst, mask_table, use_len, 16 );
+#else
+ mbedtls_platform_memcpy( b, dst, use_len );
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
UPDATE_CBC_MAC;
flow_ctrl++; /* iv_len + 3 + ( add_len? 1 : 0 ) + decryptions */
}
diff --git a/library/version_features.c b/library/version_features.c
index 8044dc9..39c098f 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -276,6 +276,9 @@
#if defined(MBEDTLS_FI_COUNTERMEASURES)
"MBEDTLS_FI_COUNTERMEASURES",
#endif /* MBEDTLS_FI_COUNTERMEASURES */
+#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
+ "MBEDTLS_CCM_SHUFFLING_MASKING",
+#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
#if defined(MBEDTLS_CAMELLIA_SMALL_MEMORY)
"MBEDTLS_CAMELLIA_SMALL_MEMORY",
#endif /* MBEDTLS_CAMELLIA_SMALL_MEMORY */