aes: validate keys using crc before encryption/decryption
CRC is calculated when the key is set. This commit also adds new tests
for ecb encryption and decryption, simulating a fault injection after the key is set.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/configs/baremetal.h b/configs/baremetal.h
index 24af9b6..71bf463 100644
--- a/configs/baremetal.h
+++ b/configs/baremetal.h
@@ -138,6 +138,7 @@
#define MBEDTLS_OID_C
#define MBEDTLS_PLATFORM_C
#define MBEDTLS_CRC_C
+#define MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY
/* I/O buffer configuration */
#define MBEDTLS_SSL_MAX_CONTENT_LEN 2048
diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index cb7d726..5fb020f 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -90,6 +90,9 @@
#if defined(MBEDTLS_AES_SCA_COUNTERMEASURES)
uint32_t frk[8]; /*!< Fake AES round keys. */
#endif
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ uint16_t crc; /*!< CRC-16 of the set key */
+#endif
#if defined(MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH) && !defined(MBEDTLS_PADLOCK_C)
uint32_t buf[44]; /*!< Unaligned data buffer */
#else /* MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH */
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 7239557..974bf7b 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -986,6 +986,10 @@
#error "MBEDTLS_HAVE_INT32/MBEDTLS_HAVE_INT64 and MBEDTLS_HAVE_ASM cannot be defined simultaneously"
#endif /* (MBEDTLS_HAVE_INT32 || MBEDTLS_HAVE_INT64) && MBEDTLS_HAVE_ASM */
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY) && ( !defined(MBEDTLS_CRC_C) )
+#error "MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY defined, but not MBEDTLS_CRC_C"
+#endif
+
/*
* Avoid warning from -pedantic. This is a convenient place for this
* workaround since this is included by every single file before the
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 98df7c5..db38e81 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2735,11 +2735,23 @@
*
* Module: library/crc.c
*
- * This module enables mbedtls_crc_update.
+ * This module enables mbedtls_crc_update().
*/
//#define MBEDTLS_CRC_C
/**
+ * \def MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY
+ *
+ * Enable validation of AES keys by checking their CRC
+ * during every encryption/decryption.
+ *
+ * Module: library/aes.c
+ *
+ * Requires: MBEDTLS_CRC_C
+ */
+//#define MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY
+
+/**
* \def MBEDTLS_GCM_C
*
* Enable the Galois/Counter Mode (GCM) for AES.
diff --git a/library/aes.c b/library/aes.c
index e7a888f..d6a6b00 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -45,6 +45,10 @@
#include "mbedtls/aesni.h"
#endif
+#if defined(MBEDTLS_CRC_C) && defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+#include "mbedtls/crc.h"
+#endif
+
#if defined(MBEDTLS_SELF_TEST)
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
@@ -703,6 +707,7 @@
AES_VALIDATE_RET( ctx != NULL );
AES_VALIDATE_RET( key != NULL );
+ (void) ret;
switch( keybits )
{
@@ -821,8 +826,6 @@
#endif /* !MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH */
}
- ret = 0;
-
/* Validate execution path */
if( ( flow_ctrl == keybits >> 5 ) && ( ( ctx->nr == 10 && i == 10 )
#if !defined(MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH)
@@ -831,7 +834,10 @@
#endif
) )
{
- return ret;
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ ctx->crc = mbedtls_crc_update( 0, ctx->rk, keybits >> 3 );
+#endif
+ return 0;
}
mbedtls_platform_memset( RK, 0, ( keybits >> 5 ) * 4 );
@@ -926,6 +932,9 @@
}
else if( ( i == 0 ) && ( j == 4 ) )
{
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ ctx->crc = mbedtls_crc_update( 0, ctx->rk, keybits >> 3 );
+#endif
return( ret );
}
else
@@ -1088,6 +1097,21 @@
// reserve based on max rounds + dummy rounds + 2 (for initial key addition)
uint8_t round_ctrl_table[( 14 + AES_SCA_CM_ROUNDS + 2 )];
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ unsigned key_bytes = 0;
+ uint16_t check_crc = 0;
+ switch( ctx->nr )
+ {
+ case 10: key_bytes = 16; break;
+#if !defined(MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH)
+ case 12: key_bytes = 24; break;
+ case 14: key_bytes = 32; break;
+#endif /* !MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH */
+ default : return( MBEDTLS_ERR_AES_INVALID_KEY_LENGTH );
+ }
+ check_crc = mbedtls_crc_update( 0, ctx->rk, key_bytes );
+#endif
+
aes_data_real.rk_ptr = ctx->rk;
aes_data_fake.rk_ptr = ctx->frk;
@@ -1182,9 +1206,20 @@
flow_control++;
} while( ( i = ( i + 1 ) % 4 ) != offset );
- if( flow_control == tindex + dummy_rounds + 8 )
+ /* Double negation is used to silence an "extraneous parentheses" warning */
+ if( ! ( flow_control != tindex + dummy_rounds + 8 )
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ && check_crc == ctx->crc
+#endif
+ )
{
- return 0;
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ mbedtls_platform_random_delay();
+ if( mbedtls_crc_update( 0, ctx->rk, key_bytes ) == ctx->crc )
+#endif
+ {
+ return 0;
+ }
}
// Clear the output in case of a FI
@@ -1369,6 +1404,21 @@
// reserve based on max rounds + dummy rounds + 2 (for initial key addition)
uint8_t round_ctrl_table[( 14 + AES_SCA_CM_ROUNDS + 2 )];
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ unsigned key_bytes = 0;
+ uint16_t check_crc = 0;
+ switch( ctx->nr )
+ {
+ case 10: key_bytes = 16; break;
+#if !defined(MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH)
+ case 12: key_bytes = 24; break;
+ case 14: key_bytes = 32; break;
+#endif /* !MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH */
+ default : return( MBEDTLS_ERR_AES_INVALID_KEY_LENGTH );
+ }
+ check_crc = mbedtls_crc_update( 0, ctx->rk, key_bytes );
+#endif
+
aes_data_real.rk_ptr = ctx->rk;
aes_data_fake.rk_ptr = ctx->frk;
@@ -1463,9 +1513,20 @@
flow_control++;
} while( ( i = ( i + 1 ) % 4 ) != offset );
- if( flow_control == tindex + dummy_rounds + 8 )
+ /* Double negation is used to silence an "extraneous parentheses" warning */
+ if( ! ( flow_control != tindex + dummy_rounds + 8 )
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ && check_crc == ctx->crc
+#endif
+ )
{
- return 0;
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ mbedtls_platform_random_delay();
+ if( mbedtls_crc_update( 0, ctx->rk, key_bytes ) == ctx->crc )
+#endif
+ {
+ return 0;
+ }
}
// Clear the output in case of a FI
diff --git a/library/version_features.c b/library/version_features.c
index 7c5dae7..84cb8a6 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -687,6 +687,9 @@
#if defined(MBEDTLS_CRC_C)
"MBEDTLS_CRC_C",
#endif /* MBEDTLS_CRC_C */
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ "MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY",
+#endif /* MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY */
#if defined(MBEDTLS_GCM_C)
"MBEDTLS_GCM_C",
#endif /* MBEDTLS_GCM_C */
diff --git a/programs/ssl/query_config.c b/programs/ssl/query_config.c
index e83671c..af77ed5 100644
--- a/programs/ssl/query_config.c
+++ b/programs/ssl/query_config.c
@@ -1874,6 +1874,14 @@
}
#endif /* MBEDTLS_CRC_C */
+#if defined(MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY)
+ if( strcmp( "MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY", config ) == 0 )
+ {
+ MACRO_EXPANSION_TO_STR( MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY );
+ return( 0 );
+ }
+#endif /* MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY */
+
#if defined(MBEDTLS_GCM_C)
if( strcmp( "MBEDTLS_GCM_C", config ) == 0 )
{
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 0a3415e..1a00ca0 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -67,6 +67,7 @@
endif(MSVC)
add_test_suite(aes aes.ecb)
+add_test_suite(aes aes.ecb.crc)
add_test_suite(aes aes.cbc)
add_test_suite(aes aes.cfb)
add_test_suite(aes aes.ofb)
diff --git a/tests/suites/test_suite_aes.ecb.crc.data b/tests/suites/test_suite_aes.ecb.crc.data
new file mode 100644
index 0000000..cd42620
--- /dev/null
+++ b/tests/suites/test_suite_aes.ecb.crc.data
@@ -0,0 +1,46 @@
+AES-128-ECB Encrypt NIST KAT #1 good CRC
+aes_encrypt_ecb_crc:"00000000000000000000000000000000":"f34481ec3cc627bacd5dc3fb08f273e6":"0336763e966d92595a567cc9ce537f5e":0:0:1
+
+AES-128-ECB Encrypt NIST KAT #1 bad CRC
+aes_encrypt_ecb_crc:"00000000000000000000000000000000":"f34481ec3cc627bacd5dc3fb08f273e6":"00000000000000000000000000000000":42:MBEDTLS_ERR_PLATFORM_FAULT_DETECTED:0
+
+AES-128-ECB Decrypt NIST KAT #1 good CRC
+depends_on:!MBEDTLS_AES_ONLY_ENCRYPT
+aes_decrypt_ecb_crc:"00000000000000000000000000000000":"db4f1aa530967d6732ce4715eb0ee24b":"ff000000000000000000000000000000":614:0:1
+
+AES-128-ECB Decrypt NIST KAT #1 bad CRC
+depends_on:!MBEDTLS_AES_ONLY_ENCRYPT
+aes_decrypt_ecb_crc:"00000000000000000000000000000000":"db4f1aa530967d6732ce4715eb0ee24b":"00000000000000000000000000000000":42:MBEDTLS_ERR_PLATFORM_FAULT_DETECTED:0
+
+AES-192-ECB Encrypt NIST KAT #1 good CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH
+aes_encrypt_ecb_crc:"000000000000000000000000000000000000000000000000":"fffffffffffffffffffff80000000000":"156f07767a85a4312321f63968338a01":0:0:1
+
+AES-192-ECB Encrypt NIST KAT #1 bad CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH
+aes_encrypt_ecb_crc:"000000000000000000000000000000000000000000000000":"fffffffffffffffffffff80000000000":"00000000000000000000000000000000":42:MBEDTLS_ERR_PLATFORM_FAULT_DETECTED:0
+
+AES-192-ECB Decrypt NIST KAT #1 good CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH:!MBEDTLS_AES_ONLY_ENCRYPT
+aes_decrypt_ecb_crc:"fffffffffffffffffffffffffffffffff000000000000000":"bb2852c891c5947d2ed44032c421b85f":"00000000000000000000000000000000":31004:0:1
+
+AES-192-ECB Decrypt NIST KAT #1 bad CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH:!MBEDTLS_AES_ONLY_ENCRYPT
+aes_decrypt_ecb_crc:"fffffffffffffffffffffffffffffffff000000000000000":"bb2852c891c5947d2ed44032c421b85f":"00000000000000000000000000000000":42:MBEDTLS_ERR_PLATFORM_FAULT_DETECTED:0
+
+AES-256-ECB Encrypt NIST KAT #1 good CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH
+aes_encrypt_ecb_crc:"c1cc358b449909a19436cfbb3f852ef8bcb5ed12ac7058325f56e6099aab1a1c":"00000000000000000000000000000000":"352065272169abf9856843927d0674fd":61384:0:1
+
+AES-256-ECB Encrypt NIST KAT #1 bad CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH
+aes_encrypt_ecb_crc:"c1cc358b449909a19436cfbb3f852ef8bcb5ed12ac7058325f56e6099aab1a1c":"00000000000000000000000000000000":"00000000000000000000000000000000":42:MBEDTLS_ERR_PLATFORM_FAULT_DETECTED:0
+
+AES-256-ECB Decrypt NIST KAT #1 good CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH:!MBEDTLS_AES_ONLY_ENCRYPT
+aes_decrypt_ecb_crc:"fffffffffffffffffffffffffffffffffffffffffffffff00000000000000000":"edf61ae362e882ddc0167474a7a77f3a":"00000000000000000000000000000000":32504:0:1
+
+AES-256-ECB Decrypt NIST KAT #1 bad CRC
+depends_on:!MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH:!MBEDTLS_AES_ONLY_ENCRYPT
+aes_decrypt_ecb_crc:"fffffffffffffffffffffffffffffffffffffffffffffff00000000000000000":"edf61ae362e882ddc0167474a7a77f3a":"00000000000000000000000000000000":42:MBEDTLS_ERR_PLATFORM_FAULT_DETECTED:0
+
diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index da8c1e9..2a2f9cb 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -1,5 +1,6 @@
/* BEGIN_HEADER */
#include "mbedtls/aes.h"
+#include "mbedtls/platform.h"
/* END_HEADER */
/* BEGIN_DEPENDENCIES
@@ -369,6 +370,60 @@
}
/* END_CASE */
+/* BEGIN_CASE depends_on:MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY:MBEDTLS_AES_SCA_COUNTERMEASURES:!MBEDTLS_AES_SETKEY_ENC_ALT:!MBEDTLS_AESNI_C */
+void aes_encrypt_ecb_crc( data_t * key_str, data_t * src_str,
+ data_t * hex_dst_string, unsigned int crc, int crypt_result, int check_crc )
+{
+ unsigned char output[100];
+ mbedtls_aes_context ctx;
+
+ memset(output, 0x00, 100);
+
+ mbedtls_aes_init( &ctx );
+
+ TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
+
+ if( check_crc )
+ TEST_ASSERT( ctx.crc == crc );
+ else
+ ctx.crc = crc;
+
+ TEST_ASSERT( mbedtls_aes_crypt_ecb( &ctx, MBEDTLS_AES_ENCRYPT, src_str->x, output ) == crypt_result );
+
+ TEST_ASSERT( hexcmp( output, hex_dst_string->x, 16, hex_dst_string->len ) == 0 );
+
+exit:
+ mbedtls_aes_free( &ctx );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_VALIDATE_AES_KEYS_INTEGRITY:MBEDTLS_AES_SCA_COUNTERMEASURES:!MBEDTLS_AES_SETKEY_ENC_ALT:!MBEDTLS_AESNI_C */
+void aes_decrypt_ecb_crc( data_t * key_str, data_t * src_str,
+ data_t * hex_dst_string, unsigned int crc, int crypt_result, int check_crc )
+{
+ unsigned char output[100];
+ mbedtls_aes_context ctx;
+
+ memset(output, 0x00, 100);
+
+ mbedtls_aes_init( &ctx );
+
+ TEST_ASSERT( mbedtls_aes_setkey_dec( &ctx, key_str->x, key_str->len * 8 ) == 0 );
+
+ if( check_crc )
+ TEST_ASSERT( ctx.crc == crc );
+ else
+ ctx.crc = crc;
+
+ TEST_ASSERT( mbedtls_aes_crypt_ecb( &ctx, MBEDTLS_AES_DECRYPT, src_str->x, output ) == crypt_result );
+
+ TEST_ASSERT( hexcmp( output, hex_dst_string->x, 16, hex_dst_string->len ) == 0 );
+
+exit:
+ mbedtls_aes_free( &ctx );
+}
+/* END_CASE */
+
/* BEGIN_CASE depends_on:MBEDTLS_CHECK_PARAMS:!MBEDTLS_PARAM_FAILED_ALT */
void aes_check_params( )
{