TMS320F28377D: using AES encryption in C2000 series

Hope_Chen

Intellectual 1000 points

Part Number: TMS320F28377D
Other Parts Discussed in Thread: C2000WARE

Hello TI engineers

Recently, our company want to use AES encryption in TI's C2000 series,

and I have found the AES encryption source in the TI's website(www.ti.com/.../aes-128)

the encryption function we used is as below,

void aes_enc_dec(unsigned char *state, unsigned char *key, unsigned char dir)

but I met some trouble when I use it,

As you know, the minimum data unit of TMS320F28377D is two byte,

that is to say, "char" type in TMS320F28377D is two byte. It is a little special with others.

so I think this function could not be used in TMS320F28377D.

is there a encryption source that could be used in TMS320F28377D? or how could I do some modification to it so that it could compliant with TMS320F28377D?

Best Regards

Hope Chen

over 6 years ago

0 Vasudha Bhadoria over 6 years ago

TI__Genius 10845 points

Hi,

I am looking into this thread and will get back shortly.

Thanks

Vasudha

0 Hope_Chen over 6 years ago in reply to Vasudha Bhadoria

Intellectual 1000 points

Hi Vasudha

Thanks for your reply,
I am not sure if I have described my issue clearly,
If you need more information about my issue,
Please contact me

Best Regards
Hope Chen

0 Eric Peeters over 6 years ago in reply to Hope_Chen

TI__Prodigy 10 points

Hi Hope,

You can always use AES_128 with only 2 bytes, you just need to fill the remaining bytes with 0's. AES is a block cipher, not a stream cipher. This means that it always encrypts 16 bytes at a time. If you could please describe to me what you are trying to achieve, I'd be happy to assist you in choosing the best solution. Thanks!

Eric Peeters

0 MatthewPate over 6 years ago in reply to Eric Peeters

TI__Guru* 80410 points

Hope,

As Eric said there are some small modifications that can be made to make the algo work with C2000's 16-bit char size. This thread has that info.

http://e2e.ti.com/support/microcontrollers/c2000/f/171/t/640459

Just to be clear, the msp430.h and those kind of references are not valid; you can just use an existing example in C2000Ware past all the system init to place the algo portion of the code(clocks will be setup, WD disabled, etc).

Matt

0 Sal Pezzino over 6 years ago in reply to MatthewPate

TI__Mastermind 32995 points

As Matt mentioned above, please see e2e.ti.com/.../640459

To get it working for C2000, you only need to modify 2 lines of code. This is because the C28x is a 16-bit word machine.

Use this function for galois_mul2()

// multiply by 2 in the galois field
unsigned char galois_mul2(unsigned char value)
{
if (value>>7)
{
return (((value << 1)^0x1b) & 0xFF);
} else
return ((value << 1) & 0xFF);
}

Regards,
sal

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TMS320F28377D: using AES encryption in C2000 series