commit fba59211869f562d5b27110815bf9007d4fda87a
author Andrzej Kurek <andrzej.kurek@arm.com> Fri Aug 07 21:02:25 2020 -0400
committer Andrzej Kurek <andrzej.kurek@arm.com> Sat Aug 08 19:06:44 2020 -0400
tree 8a5eef1c00384d7ba5d0a6d1a7136a45e6f06139
parent 9df2b416b908b7ce206386a04980ac9f6c66b57c

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>

include/mbedtls/aes.h

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 */

include/mbedtls/check_config.h

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

include/mbedtls/config.h

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.