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Merge pull request #3919 from AndrzejKurek/fi-flag-ccm-countermeasures

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Make CCM shuffling an masking optional
This commit is contained in:
Andrzej Kurek 2020-11-26 14:08:32 -05:00 committed by GitHub
commit 6994eb2b52
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 119 additions and 19 deletions
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1
configs/baremetal.h
View File

@ -158,6 +158,7 @@
/* Fault Injection Countermeasures */
#define MBEDTLS_FI_COUNTERMEASURES
#define MBEDTLS_CCM_SHUFFLING_MASKING
#if defined(MBEDTLS_USER_CONFIG_FILE)
#include MBEDTLS_USER_CONFIG_FILE

9
include/mbedtls/config.h
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@ -664,6 +664,15 @@
*/
//#define MBEDTLS_FI_COUNTERMEASURES
/**
* \def MBEDTLS_CCM_SHUFFLING_MASKING
*
* Add shuffling and masking to the CCM module as an additional security
* measure.
*
*/
//#define MBEDTLS_CCM_SHUFFLING_MASKING
/**
* \def MBEDTLS_CAMELLIA_SMALL_MEMORY
*

113
library/ccm.c
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@ -114,6 +114,7 @@ void mbedtls_ccm_free( mbedtls_ccm_context *ctx )
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 @@ static void mbedtls_generate_masks( unsigned char* table, size_t size )
table[i] = mbedtls_platform_random_in_range( 256 );
}
}
#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
/*
* Macros for common operations.
@ -159,6 +161,7 @@ static void mbedtls_generate_masks( unsigned char* table, size_t size )
* (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 @@ static void mbedtls_generate_masks( unsigned char* table, size_t size )
\
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 @@ static void mbedtls_generate_masks( unsigned char* table, size_t size )
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 @@ static void mbedtls_generate_masks( unsigned char* table, size_t size )
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
@ -224,11 +255,13 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
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.
@ -251,6 +284,7 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
mbedtls_platform_zeroize( ctr, 16 );
q = (uint_fast8_t) (16 - 1 - iv_len);
flow_ctrl++; /* 1 */
/*
* First block B_0:
@ -264,6 +298,7 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
* 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 ) |
@ -271,17 +306,31 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
( q - 1 ) ) ^ mask_table[0];
for( i = 0; i < iv_len; i++ )
{
b[i+1] = iv[i] ^ mask_table[i+1];
flow_ctrl++; /* iv_len + 1 */
}
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;
flow_ctrl++; /* iv_len + 2 */
/*
* If there is additional data, update CBC-MAC with
@ -292,30 +341,37 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
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;
UPDATE_CBC_MAC;
flow_ctrl++; /* iv_len + 2 + ( add_len? 1 : 0 ) */
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 );
#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;
@ -337,6 +393,7 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
mbedtls_platform_memcpy( ctr + 1, iv, iv_len );
mbedtls_platform_memset( ctr + 1 + iv_len, 0, q );
ctr[15] = 1;
flow_ctrl++; /* iv_len + 3 + ( add_len? 1 : 0 ) */
/*
* Authenticate and {en,de}crypt the message.
@ -354,22 +411,29 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
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 */
}
CTR_CRYPT( dst, src, use_len );
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 */
}
dst += use_len;
@ -384,6 +448,7 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
if( ++ctr[15-i] != 0 )
break;
}
flow_ctrl++; /* iv_len + 4 + ( add_len? 1 : 0 ) + enc/dec */
/*
* Authentication: reset counter and crypt/mask internal tag
@ -394,12 +459,26 @@ static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
CTR_CRYPT( y, y, 16 );
mbedtls_platform_memcpy( tag, y, tag_len );
flow_ctrl++; /* iv_len + 5 + ( add_len? 1 : 0 ) + enc/dec */
mbedtls_platform_zeroize( b, 16 );
mbedtls_platform_zeroize( y, 16 );
mbedtls_platform_zeroize( ctr, 16 );
{
size_t operations = length / 16;
operations += ( length % 16 ? 1 : 0 );
operations += ( add_len > 0 ? 1 : 0 );
/* See comments above on steps in calculating flow_ctrl */
if( flow_ctrl == iv_len + 5 + operations )
{
mbedtls_platform_random_delay();
if( flow_ctrl == iv_len + 5 + operations )
return( ret );
}
}
return( MBEDTLS_ERR_PLATFORM_FAULT_DETECTED );
}
/*
* Authenticated encryption

3
library/version_features.c
View File

@ -276,6 +276,9 @@ static const char *features[] = {
#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 */

8
programs/ssl/query_config.c
View File

@ -778,6 +778,14 @@ int query_config( const char *config )
}
#endif /* MBEDTLS_FI_COUNTERMEASURES */
#if defined(MBEDTLS_CCM_SHUFFLING_MASKING)
if( strcmp( "MBEDTLS_CCM_SHUFFLING_MASKING", config ) == 0 )
{
MACRO_EXPANSION_TO_STR( MBEDTLS_CCM_SHUFFLING_MASKING );
return( 0 );
}
#endif /* MBEDTLS_CCM_SHUFFLING_MASKING */
#if defined(MBEDTLS_CAMELLIA_SMALL_MEMORY)
if( strcmp( "MBEDTLS_CAMELLIA_SMALL_MEMORY", config ) == 0 )
{