HAL_CRYPEx_AES() maximum number of output bytes?

[dsorber]

I am using an STM32L4S9ZIJX part and attempting to encrypt a 256KB buffer (actually 262,144 - 16 = 262,128 bytes) using AES256 CTR mode in polling mode.

I created a wrapper function to perform the encryption:

int encrypt_CTR_mode(uint8_t* key, uint8_t* IV, uint8_t* plaintext, uint32_t pt_length,
                     uint8_t* ciphertext)
{
    // Deinit old parameters
    if (HAL_CRYP_DeInit(&hcryp) != HAL_OK)
    {
        LOG(error, "ERROR: HAL_CRYP_DeInit() failed\n");
        return -1;
    }

    // Setup new params
    hcryp.Init.DataType = CRYP_DATATYPE_32B;
    hcryp.Init.KeySize = CRYP_KEYSIZE_256B;
    hcryp.Init.OperatingMode = CRYP_ALGOMODE_ENCRYPT;
    hcryp.Init.ChainingMode = CRYP_CHAINMODE_AES_CTR;
    hcryp.Init.KeyWriteFlag = CRYP_KEY_WRITE_ENABLE;
    hcryp.Init.pKey = key;
    hcryp.Init.pInitVect = IV;

    // Init new parameters
    if (HAL_CRYP_Init(&hcryp) != HAL_OK)
    {
        LOG(error, "ERROR: HAL_CRYP_Init() failed\n");
        return -1;
    }

    // Encrypt plaintext
    HAL_StatusTypeDef rc;
    rc = HAL_CRYPEx_AES(&hcryp, plaintext, pt_length, ciphertext, 5000);
    if (rc != HAL_OK)
    {
        LOG(error, "ERROR: HAL_CRYPEx_AES() -- %d\n", rc);
        return -1;
    }

    return 0;
}

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The function returns successfully but I only get 65,520 (0xFFF0) output bytes even though I'm passing in 262,128 to HAL_CRYPEx_AES().  Is there some limitation for the maximum output length of HAL_CRYPEx_AES()?  I can't find any such limitation documented.

[dsorber]

Whoops... I see my problem: HAL_CRYPEx_AES() size parameter is a uint16_t.

[Tesla DeLorean]

Thankfully the source is exposed, and deeper hcryp->CrypInCount is uint32_t

You could perhaps also decompose the data into blocks