X-CUBE-CRYPTOLIB first computed SHA256 hash wrong

[POliv]

Hello,

I would like to use the X-CUBE-CRYPTOLIB to calculate a SHA256 with a key, i'm using STM32CubeIDE 1.18.0 for an STM32u083 microcontroller, STM32CubeExpansion_Crypto_V4.2.0.

The issue I have is the first time I call cmox_mac_compute the wrong result is returned.

cmox_init_arg_t init_target = {CMOX_INIT_TARGET_AUTO, NULL};

if (cmox_initialize(&init_target) != CMOX_INIT_SUCCESS)
{
  Error_Handler();
}
  
uint8_t tResult[32] = {0};
uint8_t tMessage[63] = {153,234,98,104,200,115,43,208,16,24,124,106,63,66,15,0,0,0,0,0,250,191,113,33,0,0,0,0,0,0,0,53,231,216,222,211,203,112,30,58,145,125,101,150,57,215,149,108,50,229,247,80,239,35,157,119,19,121,218,120,231,50,70};
uint8_t tKey[32] = {173,182,187,187,244,184,224,88,49,224,82,119,184,125,189,202,255,179,154,153,213,5,120,138,162,120,25,250,40,96,170,122};

//Test 1
retval = cmox_mac_compute(CMOX_HMAC_SHA256_ALGO,     // Use HMAC SHA256 algorithm
						tMessage, sizeof(tMessage),  // Message to authenticate
						tKey,sizeof(tKey),          //HMAC Key to use
						NULL, 0,                   // Custom data
						tResult,              // Data buffer to receive generated authnetication tag
						sizeof(tResult),      // Expected authentication tag size
						&computed_size);

//Test 2
retval = cmox_mac_compute(CMOX_HMAC_SHA256_ALGO,     // Use HMAC SHA256 algorithm
						tMessage, sizeof(tMessage),  // Message to authenticate
						tKey,sizeof(tKey),          //HMAC Key to use
						NULL, 0,                   // Custom data
						tResult,              // Data buffer to receive generated authnetication tag
						sizeof(tResult),      // Expected authentication tag size
						&computed_size);

The test 1 result is

tResultuint8_t [32]0x20007c5c

tResult[0] uint8_t 112 'p'

tResult[1] uint8_t 217 'Ù'

tResult[2] uint8_t 29 '\035'

tResult[3] uint8_t 236 'ì'

tResult[4] uint8_t 15 '\017'

tResult[5] uint8_t 90 'Z'

tResult[6] uint8_t 181 'µ'

tResult[7] uint8_t 180 '´'

tResult[8] uint8_t 160 ' '

tResult[9] uint8_t 231 'ç'

tResult[10] uint8_t 12 '\f'

tResult[11] uint8_t 245 'õ'

tResult[12] uint8_t 103 'g'

tResult[13] uint8_t 108 'l'

tResult[14] uint8_t 174 '®'

tResult[15] uint8_t 103 'g'

tResult[16] uint8_t 134 '\206'

tResult[17] uint8_t 203 'Ë'

tResult[18] uint8_t 184 '¸'

tResult[19] uint8_t 142 '\216'

tResult[20] uint8_t 242 'ò'

tResult[21] uint8_t 100 'd'

tResult[22] uint8_t 32 ' '

tResult[23] uint8_t 47 '/'

tResult[24] uint8_t 122 'z'

tResult[25] uint8_t 0 '\0'

tResult[26] uint8_t 164 '¤'

tResult[27] uint8_t 176 '°'

tResult[28] uint8_t 160 ' '

tResult[29] uint8_t 179 '³'

tResult[30] uint8_t 55 '7'

tResult[31] uint8_t 114 'r'

and the test 2 result is

tResultuint8_t [32]0x20007c5c

tResult[0] uint8_t 18 '\022'

tResult[1] uint8_t 119 'w'

tResult[2] uint8_t 126 '~'

tResult[3] uint8_t 117 'u'

tResult[4] uint8_t 190 '¾'

tResult[5] uint8_t 209 'Ñ'

tResult[6] uint8_t 204 'Ì'

tResult[7] uint8_t 56 '8'

tResult[8] uint8_t 127 '\177'

tResult[9] uint8_t 227 'ã'

tResult[10] uint8_t 113 'q'

tResult[11] uint8_t 213 'Õ'

tResult[12] uint8_t 119 'w'

tResult[13] uint8_t 195 'Ã'

tResult[14] uint8_t 171 '«'

tResult[15] uint8_t 156 '\234'

tResult[16] uint8_t 223 'ß'

tResult[17] uint8_t 163 '£'

tResult[18] uint8_t 229 'å'

tResult[19] uint8_t 132 '\204'

tResult[20] uint8_t 118 'v'

tResult[21] uint8_t 137 '\211'

tResult[22] uint8_t 111 'o'

tResult[23] uint8_t 233 'é'

tResult[24] uint8_t 171 '«'

tResult[25] uint8_t 255 'ÿ'

tResult[26] uint8_t 100 'd'

tResult[27] uint8_t 209 'Ñ'

tResult[28] uint8_t 14 '\016'

tResult[29] uint8_t 233 'é'

tResult[30] uint8_t 204 'Ì'

tResult[31] uint8_t 218 'Ú'

The test 2 result is correct. Any idea what could be causing this?

[Pavel A.]

IIRC this is documented somewhere in the cryptolib. Practically, the user of cryptolib simply ignores existence of CRC: does not enable CRC in the cube, does not call __HAL_CRC_DR_RESET(hcrc) and so on.