Ok, thank you for your help. 2011/6/2 Jakob Bieling <[email protected]>: > Hi again, > > one more follow-up. I mixed up on-the-fly encryption with standalone > encryption: > > - standalone encryption on the CC2420 really allows encryption only and does > not use CTR mode, ie. if you encrypt data, you cannot decrypt it, unless you > use a specific cipher mode (like CTR) > - on-the-fly encryption uses CTR mode and here the process for encrypting > and decrypting is the same (tho you would not have to care about that, since > the chip does pretty much everything for you) > > This means, you can use the standalone encryption only in cipher modes like > CTR, where only the encryption process is needed. Consequently, you will have > to implement your own CTR mode, if you want to be able to decrypt your data. > If you are not familiar with CTR, Wikipedia is a good place to start. > > Best, > Jakob > > > On Jun 2, 2011, at 10:17 AM, Jakob Bieling wrote: > >> Hi, >> >> On Jun 2, 2011, at 10:02 AM, Damian Rusinek wrote: >>> Unfortunately encrypting the ciper again does not decrypt it. >> >> In the sample code, try setting the plain text to >> >> uint8_t aes_plaintext[16] = { >> 0x69, 0xc4, 0xe0, 0xd8, 0x6a, 0x7b, 0x04, 0x30, >> 0xd8, 0xcd, 0xb7, 0x80, 0x70, 0xb4, 0xc5, 0x5a, >> }; >> >> and check what the encrypted text is. Make sure the rest of the sample code >> is unchanged! >> >>> To >>> decrypt, you need to provide generated keys in inverted order. That's >>> what I want to achieve. >> >> I am not sure what you mean by that. In general, the CC2420 needs inversion >> of the key-bytes, because the key is read like that (i.e., backwards) into >> RAM. But this affects encryption as well as decryption and is already done >> by that library. You should not need to invert anything. >> >> Best, >> Jakob >> >> >>> 2011/6/2 Jakob Bieling <[email protected]>: >>>> try "encryting" the cipher text again. The CC2420 AES works in CTR mode, >>>> meaning encryption and decryption are the same operation. >>>> >>>> Moreover, if you send your packets anyway, you can use the built-in >>>> functionality of the CC2420 chip to encrypt all outgoing packets on the >>>> fly. It will also decrypt incoming packets automatically. TinyOS already >>>> allows for this, simply Google for "tinyos cc2420 security tutorial". Note >>>> that the actual wiki seems to be down, but you use the Google cache. That >>>> worked for me. >>>> >>>> On Jun 2, 2011, at 9:07 AM, Damian Rusinek wrote: >>>> >>>>> Hello. >>>>> I'm using 'The Standalone AES Encryption of CC2420' which is described >>>>> here: >>>>> http://cis.sjtu.edu.cn/index.php/The_Standalone_AES_Encryption_of_CC2420_(TinyOS_2.10_and_MICAz) >>>>> >>>>> I encrypt the payload of my packet before sending. >>>>> The question is how can I decrypt it? >>>>> Does anybody use this library? >> -- >> net.cs.bonn.edu/bieling >> >> >> _______________________________________________ >> Tinyos-help mailing list >> [email protected] >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > -- > net.cs.bonn.edu/bieling > >
-- Pozdrawiam, Damian Rusinek. _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
