AES Encryption with SD

RE: AES Encryption with SD

codebreaker176 — Thu, 27 Aug 2020 06:24:20 GMT

Alright thanks!

RE: AES Encryption with SD

run_ar — Wed, 26 Aug 2020 13:11:52 GMT

I think that's already described in the code example in this thread. Just need to replace p_data with whatever date you want to encrypt. once that is done you add the encrypted data to manufacturer specific data in the advertisement packet.

RE: AES Encryption with SD

codebreaker176 — Mon, 24 Aug 2020 14:39:51 GMT

Hi,

Can you give an example how to use the security key in the code?

Like how and where is the security key supposed to be used.

And how to automatically generate a security key?

RE: AES Encryption with SD

run_ar — Thu, 20 Aug 2020 08:03:39 GMT

Hi,

You can use the same procedure as described earlier to encrypt the data before placing it in the advertisement data as manufacturer specific data. However you also need a good (secure) way to exchange the secure key, if that is in place and you use counter mode it should be quite secure.

RE: AES Encryption with SD

codebreaker176 — Thu, 20 Aug 2020 07:24:24 GMT

Hi,

Did you get what to do for this

[quote userid="76983" url="~/f/nordic-q-a/13429/aes-encryption-with-sd/180655"]i need encrypt the advertising data like uuid,major&minor of my beacon so that it cannot be visible to other app or nrf connect it should be visible only to self designed app[/quote]

If so can you please share

RE: AES Encryption with SD

Naralasetty Praneeth — Mon, 08 Apr 2019 08:08:11 GMT

hi @run_ar

i need encrypt the advertising data like uuid,major&minor of my beacon so that it cannot be visible to other app or nrf connect it should be visible only to self designed app

for this which code i should use

RE: AES Encryption with SD

run_ar — Wed, 01 Feb 2017 13:04:42 GMT

Compared to the "block cipher mode of operation" article on wikipedia: p_data is the actuall data you want to encrypt (plaintext). aes_struct.ciphertext is the same as the "block chiper encryption" block output. So when aes_struct.ciphertext is xor'ed with p_data you get what is named ciphertext in the counter mode overview in the wikipedia article (encrypted data ready to send). Obviously it's a bit confusion since there are two chipertexts... But the AES block supports encryption, not decryption which is why it's done like this.

RE: AES Encryption with SD

cherrycherry1 — Mon, 30 Jan 2017 08:12:36 GMT

Hi! Thanks for this example of AES XOR, but I was wondering if you could help me out a bit. I'm not a crypto pro but I got the following:

You init all variables and memset them to 0
you make a key, which is now just simply 0x00010203040506070809....
you set the whole plain text (clear text/text you want to encrypt) to 0xaa......
Enctypt it all
XOR p_data with the ciphertext. (1)
to decode to XOR the received enctypted aes_data with a ciphertext (2)

What I dont get is for point (1) What is p_data and what is where does the ciphertext come from? Is p data the raw data (so p_data = cleartext). Wikipedia stated that " he key size used for an AES cipher specifies the number of repetitions of transformation rounds that convert the input, called the plaintext, into the final output, called the ciphertext." If so, then (2) states that the ciphertext is known on the dec side

RE: AES Encryption with SD

run_ar — Thu, 08 Dec 2016 14:23:31 GMT

It's been a while, but it probably means "pointer to data, refering to the data you wish to encrypt" or something like that...

RE: AES Encryption with SD

gjk — Thu, 08 Dec 2016 13:25:06 GMT

p_data ???

RE: AES Encryption with SD

run_ar — Tue, 10 May 2016 09:07:31 GMT

The AES block is used to create a chippertext, this can be used to encrypt/decrypt data as shown below:

nrf_ecb_hal_data_t aes_struct;

uint8_t aes_data[16];

uint8_t aes_data_decrypted[16];



//Initializing arrays

memset (&aes_struct, 0, sizeof(aes_struct));

memset (aes_data, 0, sizeof(aes_data));

memset (aes_data_decrypted, 0, sizeof(aes_data_decrypted));



//Initializing key

for (int i = 0; i < 16; i++)

{

    aes_struct.key [i] = i;

}



//Initializing nouncence

memset (aes_struct.cleartext, 0xaa, sizeof(aes_struct.cleartext)); //todo: use more random data and add counter



//Creating chipertext

sd_ecb_block_encrypt(&aes_struct);  



//Encrypt -> XOR chipertext with p_data:

for (int i = 0; i < length; i++)

{  

    aes_data[i] = p_data [i] ^ aes_struct.ciphertext[i];

}



//decrypt -> XOR chipertext with Encrypted data:

for (int i = 0; i < length; i++)

{  

    aes_data_decrypted[i] = aes_data [i] ^ aes_struct.ciphertext[i];

}

RE: AES Encryption with SD

leehong — Wed, 04 May 2016 18:10:34 GMT

Yes, new data comes in every 10s. I'm using the S110 sd.

RE: AES Encryption with SD

run_ar — Wed, 04 May 2016 12:36:42 GMT

I haven't seen this before. Can you confirm that the data coming in from the other chip is actually changing? And which Softdevice version are you using?

RE: AES Encryption with SD

leehong — Wed, 27 Apr 2016 18:58:53 GMT

The value doesn't change. data in (clear_text) is data coming in from another chip at 10sec intervals. It seems the softdevice is too busy to process encryption?

RE: AES Encryption with SD

run_ar — Wed, 27 Apr 2016 11:42:47 GMT

What do you mean when you say that you are not getting any new values from cipher text? Do you mean you are not getting a value at all or that the value don't change? What data are you putting in, static or do you have a counter (ref counter mode)?