AES encryption/decryption code

Elian Lima

Other Parts Discussed in Thread: CC2530

Hello,

I´m Trying to use the sample code from the DN108 - Using AES Encryption in C111xFx, CC243x and CC251xFx to try to program an encryption code in my project. I´m using the CC2530, so is it possible?

If not is there any DN, AN or another thing that can help me to encrypt and decrypt my data?

over 14 years ago

0 Elian Lima over 14 years ago

Expert 1895 points

I´ve just forget to say that I´m using the code without DMA from section 4.2 of the document I said.

0 muhammad waqar azhar over 14 years ago in reply to Elian Lima

Prodigy 195 points

Hi,

Example code for encryption without DMA is also given in this app note as well.

If you have any specific question, i can try to awnser

0 Elian Lima over 13 years ago in reply to muhammad waqar azhar

Expert 1895 points

So...

I´m using the code for encryption without DMA like you said, but when I try to execute it, I put a breakpoint in every line of the specific code one at a time, and when I put the breakpoint after the last line: while(!(ENCCS & 0x08)); it didn´t get there. I don´t know why, because befores the NOP´s it works, and in this linte it doesn´t work. Can you helo me?

0 muhammad waqar azhar over 13 years ago in reply to Elian Lima

Prodigy 195 points

Hi,

well its difficult to tell this way, which mode are you using for encryption.

If possible can you send the code, i can have a look

regard

waqar

0 Elian Lima over 13 years ago in reply to muhammad waqar azhar

Expert 1895 points

I´m using exactly the code from the section 4.2 of the document, that is the mode without DMA. The code is as follows:

// Define size parameters for the AES processing:

#define SIZE_OF_ENC_BUFFER 128

#define SIZE_OF_AES_BLOCK 16

#define SIZE_OF_ENC_PACKET 8*SIZE_OF_AES_BLOCK

__no_init BYTE __xdata aes_buffer_1[SIZE_OF_ENC_BUFFER]; // Source buffer

__no_init BYTE __xdata aes_buffer_2[SIZE_OF_ENC_BUFFER]; // Target buffer

unsigned short i, j;

// Define size of AES block

#define SIZE_OF_AES_BLOCK 16

// Allocate source buffers for AES key and IV/NONCE

__no_init unsigned char __xdata key[SIZE_OF_AES_BLOCK];

__no_init unsigned char __xdata iv_nonce[SIZE_OF_AES_BLOCK];

unsigned short i;

// Generate Key:

// In a radio application this is typically generated based on

// a standard/protocol specification. However, for simplicity,

// this design note does not use any particular specification

// for generating it.

for(i = 0; i < SIZE_OF_AES_BLOCK; i++) { key[i] = i * 2; }

// Download Key (Set ENCCS.CMD = 10b),

// and start corresponding AES process (ENCCS.ST = 1)

ENCCS = 0x04 | 0x01;

for (i = 0; i < SIZE_OF_AES_BLOCK; i++) {

ENCDI = key[i];

}

// Monitor AES (ENCCS.RDY) to wait until key downloaded

while(!(ENCCS & 0x08));

// Generate IV/NONCE:

// In a radio application this is typically generated based on

// a standard/protocol specification. However, for simplicity,

// this design note does not use any particular specification

// for generating it.

for(i = 0; i < SIZE_OF_AES_BLOCK; i++) { iv_nonce[i] = i; }

// Dwonload IV/NONCE (Set ENCCS.CMD = 11b)

// and start corresponding AES process (ENCCS.ST = 1)

ENCCS = 0x06 | 0x01;

for (i = 0; i < SIZE_OF_AES_BLOCK; i++) {

ENCDI = iv_nonce[i];

}

// Monitor AES (ENCCS.RDY) to wait until IV/NONCE downloaded

while(!(ENCCS & 0x08));

// Perform AES encryption/decryption on allocated AES buffer ("aes_buffer_1"):

for (j = 0; j < SIZE_OF_ENC_PACKET/SIZE_OF_AES_BLOCK; j++) {

// Configure and start AES coprocessor for the desired AES mode:

// Encryption => ENCCS.CMD = 00b, decryption mode => ENCCS.CMD = 01b.

// Use so-called Cipher Block Chaining encryption mode => ENCCS.MODE = 000b.

// Start AES processing (ENCCS.ST = 1) of source buffer (aes_buffer_1).

ENCCS = 0x00 | 0x01; // Only valid for encryption mode !

//ENCCS = 0x02 | 0x01; // Only valid for decryption mode !

// Download data block (16 bytes) to AES coprocessor:

// In encryption mode "aes_buffer_1" represents the data to be encrypted.

// In decryption mode "aes_buffer_1" represents the data to be decrypted.

for (i = 0; i < SIZE_OF_AES_BLOCK; i++) {

ENCDI = aes_buffer_1[i+(j*SIZE_OF_AES_BLOCK)];

}

// Wait until AES download is finished, that is; apply delay

// equivalent to 40 NOPs:

asm("NOP");asm("NOP");asm("NOP");asm("NOP");asm("NOP");asm("NOP");asm("NOP");

asm("NOP");asm("NOP");asm("NOP");asm("NOP");asm("NOP");

// Upload data block (16 bytes) to allocated AES buffer:

// In encryption mode "aes_buffer_2" represents the encrypted data.

// In decryption mode "aes_buffer_2" represents the decrypted data.

for (i = 0; i < SIZE_OF_AES_BLOCK; i++) {

aes_buffer_2[i+(j*SIZE_OF_AES_BLOCK)] = ENCDO;

}

// Monitor AES (ENCCS.RDY) to wait until data block downloaded

while(!(ENCCS & 0x08));

}

I´ve just copied and paste from the document in my code and above.

The loop for (j = 0; j < SIZE_OF_ENC_PACKET/SIZE_OF_AES_BLOCK; j++) { } is done just one time, and I couldn´t understand why.

Can you help?

Sub-1 GHz

Sub-1 GHz forum

AES encryption/decryption code