AES Encryption and Decryption using CCM mode

RE: AES Encryption and Decryption using CCM mode

PK424 — Mon, 20 May 2024 03:16:40 GMT

Hi Hieu,

Thank you for your response. I understand that you will be partially out of office and I appreciate your heads-up about potential delays in follow-up.

I have indeed switched to the latest version of the SDK as you suggested. I have also gone through the Cryptography examples in the nRF5 SDK and the Cryptography Library’s documentation. They were quite helpful.

PK424

RE: AES Encryption and Decryption using CCM mode

Hieu — Wed, 15 May 2024 12:58:39 GMT

Hi PK424,

We have a short holiday coming soon, and I am partially out of office from now and for the working days before and after that. Thus, it will be hard to schedule debugging.

Have you tried to look at the Cryptography examples in the nRF5 SDK? It might be helpful to also go over the Cryptography Library's documentation before and after you do.

Which version of the SDK are you using? I hope you have moved to the latest version.

By the way, due to the above-mentioned unavailability, please excuse some delay in further follow up. I am sorry for the inconvenience.

Hieu

RE: AES Encryption and Decryption using CCM mode

PK424 — Wed, 15 May 2024 05:59:01 GMT

Hi Hieu

I have written the code for AES encryption and decryption for nrf52832 the code is

int main(void)
{
 // Define the key, nonce, and input data
 aes_nonce_key_t nk = {
 .key = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F},
 .nonce = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C},
 .scratch = {0} // Initialize scratch area
 };
 uint8_t input[16] = "Hello, World!";
 uint8_t encrypted[20];
 uint8_t decrypted[16];
 /* Bootloader code */
 /* Initialize the system clock */
 InitSysClock();
 /* Initialize the system gpios */
 InitSysGpio();
 /* Initialize the UARTE0 */
 InitHostCon();
 // Encrypt the data
 aes_encrypt(&nk, input, encrypted);
 // Decrypt the data
 aes_decrypt(&nk, encrypted, decrypted, sizeof(decrypted));
 // Print the input data
 print_data("Input", input, sizeof(input));
 // Print the encrypted data
 print_data("Encrypted", encrypted, sizeof(encrypted));
 // Print the decrypted data
 print_data("Decrypted", decrypted, sizeof(decrypted));
 // Verify that the decrypted data matches the input data
 if(memcmp(input, decrypted, sizeof(input)) == 0) {
 // Success: The decrypted data matches the input
 printf("Decryption successful: Decrypted data matches input.\n");
 } else {
 // Error: The decrypted data does not match the input
 printf("Decryption failed: Decrypted data does not match input.\n");
 }
}
// Function to generate key-stream
void aes_generate_keystream(aes_nonce_key_t* nk){
 // Enable the CCM
 NRF_CCM->ENABLE = CCM_ENABLE_ENABLE_Enabled << CCM_ENABLE_ENABLE_Pos;
 // Set the key and nonce
 NRF_CCM->CNFPTR = (uint32_t) nk;
 // Set the scratch pointer for temporary key-stream storage
 NRF_CCM->SCRATCHPTR = (uint32_t) nk->scratch;
 // Start key-stream generation
 NRF_CCM->TASKS_KSGEN = 1;
 // Wait for key-stream generation to complete
 while (NRF_CCM->EVENTS_ENDKSGEN == 0);
}
// Function to encrypt data
void aes_encrypt(aes_nonce_key_t* nk, uint8_t* input, uint8_t* output){
 // Generate key-stream
 aes_generate_keystream(nk);
 // Set the input and output pointers
 NRF_CCM->INPTR = (uint32_t) input;
 NRF_CCM->OUTPTR = (uint32_t) output;
 // Set mode to encryption
 NRF_CCM->MODE = CCM_MODE_MODE_Encryption;
 // Start the encryption
 NRF_CCM->TASKS_CRYPT = 1;
 // Wait for the encryption to complete
 while (NRF_CCM->EVENTS_ENDCRYPT == 0);
}
// Function to decrypt data
void aes_decrypt(aes_nonce_key_t* nk, uint8_t* input, uint8_t* output, size_t len){
 // Ensure CCM is enabled and configured correctly
 NRF_CCM->ENABLE = CCM_ENABLE_ENABLE_Enabled << CCM_ENABLE_ENABLE_Pos;
 // Set the key and nonce
 NRF_CCM->CNFPTR = (uint32_t) nk;
 // Set the input and output pointers
 NRF_CCM->INPTR = (uint32_t) input;
 NRF_CCM->OUTPTR = (uint32_t) output;
 NRF_CCM->MODE = CCM_MODE_MODE_Decryption; // Set mode to decryption
 // Set the packet length
 NRF_CCM->MODE &= ~CCM_MODE_LENGTH_Msk;
 NRF_CCM->MODE |= ((len << CCM_MODE_LENGTH_Pos) & CCM_MODE_LENGTH_Msk);
 // Start the decryption
 NRF_CCM->TASKS_CRYPT = 1;
 while (NRF_CCM->EVENTS_ENDCRYPT == 0); // Wait for the decryption to complete
 // Check MIC status
 if (NRF_CCM->MICSTATUS != 0) {
 printf("MIC check failed.\n");
 } else {
 printf("MIC check passed.\n");
 }
}
/* --------------------------------------------------------------------------------*/

The output of code is 

00> MIC check passed.
00> Input: 48 65 6c 6c 6f 2c 20 57 6f 72 6c 64 21 00 00 00 
00> Encrypted: 04 d5 9c e9 86 7c 36 17 36 b1 f4 a5 79 21 ff 7b 50 48 00 b0 
00> Decrypted: 48 65 6c 6c 6f 2c 20 57 f3 39 ec 1a 05 af 66 51 
00> Decryption failed: Decrypted data does not match input.


The output which is generating the decrypted data do not match with the input data.
Can you pleas guide me with this what is wrong in the code.

RE: AES Encryption and Decryption using CCM mode

PK424 — Tue, 14 May 2024 08:28:43 GMT

Hi Hieu

Thank you for the link the link is working, but can you guide me with how can I use hardware ccm method without using nRF Connect SDK for encryption and decryption of data.

PK424

RE: AES Encryption and Decryption using CCM mode

Hieu — Tue, 14 May 2024 08:00:00 GMT

Hi PK424,

It looks like the comma character got combined into the link. Sorry for the inconvenience. Please use this link:
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.1/nrf/index.html

I will also fix the previous link.

In the nRF Connect SDK, the crypto library is setup so that, by default, if the hardware supports the crypto operation, then it will be done by hardware. Otherwise, a software library will be used.

Hieu

RE: AES Encryption and Decryption using CCM mode

PK424 — Mon, 13 May 2024 13:01:14 GMT

Hi Hieu

Thank you for the guidance but can you guide me with how can I use hardware ccm method for encryption and decryption of data without using the nordic's SDK and also the links you provided this link " https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.1/nrf/index.html," is out of use it says 'Page not found'.

PK424

RE: AES Encryption and Decryption using CCM mode

Hieu — Mon, 13 May 2024 08:01:23 GMT

Hi PK424,

The example you followed is very old. It is based on the nRF5 SDK, which is in maintenance mode and is not recommended on any new project. Not only that, but it is also based on an old version of the SDK.

Unless you have a strong reason to use the nRF5 SDK, I highly recommend you move to the nRF Connect SDK.
You can find the documentation here: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.1/nrf/index.html, and
cryptography samples for the SDK here: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.1/nrf/samples/crypto.html.

Hieu