STM32H563 Trustzone cmox hardfault

[DBara.1]

Hello. I am trying to encrypt/decrypt data in secure area of stm32h563 (Trustzone application), using code from one of the examples (using  cmox_cipher_encrypt function). Running the function in non-secure area, everything works fine. Trying to run that in secure area immediatly hardfaults. It seems like problem might be that the library tries to access something in the non secure area. Initial thought was CRC engine, but in cubemx i specificly initialized that to secure area because it will be used in there. Is there some known workaround or updated libraries to use cmox_cipher_encrypt in secure area?

[DBara.1]

To follow-up on this: Tried running cmox_cipher_encrypt functions in non secure area. Those works fine, but there are two key things:
1) First encrypted output is completely different from the all others (Running 10 loops of same code, first run gives values which differ from other 9 runs). Based on previous talks in the forum, that seems to be some kind of problem with how cmox uses CRC engine, CRC might have some default init values.
2) Even when getting same values on the remaining 9 runs, nothing matches online AES256-CBC calculator. Tried running the code using NIST test vectors and result does not match. 

[lobna]

Dear @DBara.1 

Please provide the following information so we can analyze the issue further. If possible, include a minimal reproducible example and the exact test vector used.

• Device / Software:
  - STM32 part number:
  - Package / revision:
  - STM32Cube version:
  - CMOX version:
  - Compiler / toolchain:
  - IDE version:
• Execution Context:
  - Secure or Non-Secure execution:
  - TrustZone enabled:
  - SAU configuration:
  - GTZC configuration:
  - MPU configuration:
• CRC Setup:
  - Is the CRC clock enabled before the first crypto call?
  - Is the CRC peripheral reset to a known state?
  - Does any other code access CRC before CMOX?
  - Is CRC assigned to the correct security domain?
  - CRC initialization code:
• Crypto Parameters:
  - Algorithm:
  - Mode:
  - Key size:
  - IV size:
  - Padding mode:
  - Input length:
• Test Vector:
  - Exact key:
  - Exact IV:
  - Plaintext:
  - Expected ciphertext:
  - Actual ciphertext:
• Memory Placement:
  - Input buffer address:
  - Output buffer address:
  - Are the buffers located in Secure RAM?
  - Are the buffers properly aligned?
  - Linker section used:
• Reproduction Behavior:
  - Is the first run different from the subsequent runs?
  - Are all runs identical?
  - Does it match the online calculator?
  - Does it match the NIST vector?
  - Number of iterations tested:
• Fault Information:
  - HardFault occurs:
  - SecureFault occurs:
  - CFSR:
  - HFSR:
  - BFAR:
  - MMFAR:
  - Stacked PC:
  - Stacked LR:
  - Call stack:

Best regards 

Lobna

[DBara.1]

Hello, 
Im not that advanced yet to understand like half of the things you asked for, but i will try :)
If it would be easier i can just upload whole project somewhere, but generally: Opened CubeMX, Select STM32H563ZIT (MCU on Nucleo-H563ZI board).Activate CRC to Cortex-M33 secure, generate code. Add ST Cryptography libraries to project, write minimal cmox_ciper_encrypt test code in secure area, write linker function to call this from non secure area, make the call. Code reaches cmox_cipher_encrypt() function and then hardfaults. 

• Device / Software:
  - STM32H563ZIT6
  - LQFP-144
  - STM32CubeMX version: 6.17.0
  - CMOX version: No idea where to find this, but generally libraries 
  - Compiler / toolchain: arm-none-eabi-gcc
  - IDE version: 2.1.0
  
  
• Execution Context:
  - Secure or Non-Secure execution: Executing encryption function in Secure zone
  - TrustZone enabled: Yes
  - SAU configuration: Default?
  - GTZC configuration: Default?
  - MPU configuration: Default?
• CRC Setup:
  - Is the CRC clock enabled before the first crypto call? No
  - Is the CRC peripheral reset to a known state? Should be in its default state after initialization
  - Does any other code access CRC before CMOX? No
  - Is CRC assigned to the correct security domain? Yes
  - CRC initialization code:
  
   

static void MX_CRC_Init(void)
{
/* USER CODE BEGIN CRC_Init 0 */
/* USER CODE END CRC_Init 0 */
/* USER CODE BEGIN CRC_Init 1 */
/* USER CODE END CRC_Init 1 */
hcrc.Instance = CRC;
hcrc.Init.DefaultPolynomialUse = DEFAULT_POLYNOMIAL_ENABLE;
hcrc.Init.DefaultInitValueUse = DEFAULT_INIT_VALUE_ENABLE;
hcrc.Init.InputDataInversionMode = CRC_INPUTDATA_INVERSION_NONE;
hcrc.Init.OutputDataInversionMode = CRC_OUTPUTDATA_INVERSION_DISABLE;
hcrc.InputDataFormat = CRC_INPUTDATA_FORMAT_BYTES;
if (HAL_CRC_Init(&hcrc) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN CRC_Init 2 */
/* USER CODE END CRC_Init 2 */
}

• Crypto Parameters:
  - Algorithm: AES-256
  - Mode: CBC
  - Key size: 32 bytes
  - IV size: 16 bytes
  - Padding mode: None
  - Input length: 16 bytes
• Test Vector: 
  - Exact key: 0x603DEB1015CA71BE2B73AEF0857D77811F352C073B6108D72D9810A30914DFF4
  - Exact IV: 0x000102030405060708090A0B0C0D0E0F
  - Plaintext: 0x6BC1BEE22E409F96E93D7E117393172A
  - Expected ciphertext: 0xF58C4C04D6E5F1BA779EABFB5F7BFBD6
  - Actual ciphertext:Hardfault
• Memory Placement:
  Would be good to know how to check all of theese. Buffers are generally declared as uint8_t key[32] and so before calling all of the cmox functions.
  - Input buffer address:
  - Output buffer address:
  - Are the buffers located in Secure RAM?
  - Are the buffers properly aligned?
  - Linker section used:
• Reproduction Behavior:
  - Is the first run different from the subsequent runs? No
  - Are all runs identical? Yes
  - Does it match the online calculator? Hardfault
  - Does it match the NIST vector? Hardfault
  - Number of iterations tested: a lot
• Fault Information:
  - HardFault occurs: Yes
  - SecureFault occurs: No
  - CFSR: 1048576
  - HFSR: 1073741824
  - BFAR: 805633116
  - MMFAR: 805633116
  - Stacked PC: 0xc0019d8
  - Stacked LR: -23
  - Call stack: Corrupted.
  
  For the second part of the problem, when running same exact code in non-secure area:
  Getting different values for the first run compared to all other runs seems to have been some other function using CRC engine before the encryption, that got sorted out with the fresh project and only encryption function tests. Besides that, return value still does not match the expected value. 
  Expected ciphertext from NIST: 0xF58C4C04D6E5F1BA779EABFB5F7BFBD6 
  Actual ciphertext from STM: 0x17A6495D11D8BEF42610AD89AFBD5633
  Returned ciphertext does not match neither NIST nor online calculator (online calculator matches NIST).
  Code snippet for actual encryption:
  
   

cmox_cbc_handle_t Cbc_Ctx;
uint8_t key[32] = {0x60,0x3D,0xEB,0x10,0x15,0xCA,0x71,0xBE,0x2B,0x73,0xAE,0xF0,0x85,0x7D,0x77,0x81,0x1F,0x35,0x2C,0x07,0x3B,0x61,0x08,0xD7,0x2D,0x98,0x10,0xA3,0x09,0x14,0xDF,0xF4};
uint8_t iv[16] = {0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F};
uint8_t input[16] = {0x6B,0xC1,0xBE,0xE2,0x2E,0x40,0x9F,0x96,0xE9,0x3D,0x7E,0x11,0x73,0x93,0x17,0x2A};
uint8_t output[16] = {0};
cmox_cipher_retval_t retval;
size_t computed_size;
cmox_cipher_handle_t *cipher_ctx;
uint32_t index;
cmox_init_arg_t init_target = {CMOX_INIT_TARGET_AUTO, NULL};
if (cmox_initialize(&init_target) != CMOX_INIT_SUCCESS)
{
Error_Handler();
}
retval = cmox_cipher_encrypt(CMOX_AES_CBC_ENC_ALGO, input, sizeof(input), key, sizeof(key),iv, sizeof(iv), output, &computed_size);
HAL_Delay(10);

Best regards, 
Dainius

[lobna]

Dear @DBara.1 

Thank you for your prompt response. Would it be possible to upload a ZIP file containing the entire project?

Best regards

Lobna