From fba59211869f562d5b27110815bf9007d4fda87a Mon Sep 17 00:00:00 2001 From: Andrzej Kurek Date: Fri, 7 Aug 2020 21:02:25 -0400 Subject: [PATCH] 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 --- configs/baremetal.h | 1 + include/mbedtls/aes.h | 3 + include/mbedtls/check_config.h | 4 ++ include/mbedtls/config.h | 14 ++++- library/aes.c | 75 +++++++++++++++++++++--- library/version_features.c | 3 + programs/ssl/query_config.c | 8 +++ tests/CMakeLists.txt | 1 + tests/suites/test_suite_aes.ecb.crc.data | 46 +++++++++++++++ tests/suites/test_suite_aes.function | 55 +++++++++++++++++ 10 files changed, 202 insertions(+), 8 deletions(-) create mode 100644 tests/suites/test_suite_aes.ecb.crc.data diff --git a/configs/baremetal.h b/configs/baremetal.h index 24af9b670..71bf463e7 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 cb7d726ae..5fb020fa8 100644 --- a/include/mbedtls/aes.h +++ b/include/mbedtls/aes.h @@ -90,6 +90,9 @@ typedef struct mbedtls_aes_context #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 7239557a0..974bf7b1f 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 98df7c58c..db38e81cc 100644 --- a/include/mbedtls/config.h +++ b/include/mbedtls/config.h @@ -2735,10 +2735,22 @@ * * 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 * diff --git a/library/aes.c b/library/aes.c index e7a888f1a..d6a6b0097 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 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key, AES_VALIDATE_RET( ctx != NULL ); AES_VALIDATE_RET( key != NULL ); + (void) ret; switch( keybits ) { @@ -821,8 +826,6 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key, #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 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key, #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 @@ exit: } 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 @@ int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx, // 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 @@ int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx, 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 @@ int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx, // 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 @@ int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx, 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 7c5dae79c..84cb8a62b 100644 --- a/library/version_features.c +++ b/library/version_features.c @@ -687,6 +687,9 @@ static const char *features[] = { #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 e83671c16..af77ed553 100644 --- a/programs/ssl/query_config.c +++ b/programs/ssl/query_config.c @@ -1874,6 +1874,14 @@ int query_config( const char *config ) } #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 0a3415e34..1a00ca0b0 100644 --- a/tests/CMakeLists.txt +++ b/tests/CMakeLists.txt @@ -67,6 +67,7 @@ if(MSVC) 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 000000000..cd4262058 --- /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 da8c1e935..2a2f9cbcd 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 @@ exit: } /* 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( ) {