Prev: Keil C51/ 8051 port of uIP v0.9 TCP/IP stack.
Next: TCP/IP stack for GPRS
From: Tina on 11 Feb 2005 18:01
Hello

Can anyone guide me on the implementation of encryption algorithm
using microcontroller?
From: Tina on 12 Feb 2005 22:20
teenamalik(a)hotmail.com (Tina) wrote in message news:<bbaa8f6a.0502111501.5fcef39d(a)posting.google.com>...
> Hello
>
> Can anyone guide me on the implementation of encryption algorithm
> using microcontroller?

Thanks all for the reply.
I'm planning to implement the algorihm using 8051 controller and
stream cipher encryption.
From: Oliver Betz on 15 Feb 2005 15:13
"Wim Ton" <wimton(a)blueyonder.co.uk> wrote:

>> I'm planning to implement the algorihm using 8051 controller and
>> stream cipher encryption
>
>RC4 is a well established stream algorithm, but needs 512 bytes of RAM, RC5
>may be a better choice.

LFSRs, maybe two combined, need close to nothing (RAM, ROM, time).

What are the disadvantages?

Oliver
--
Oliver Betz, Muenchen (oliverbetz.de)
From: Guy Macon on 18 Feb 2005 16:59



R Adsett wrote:
>
>Guy Macon <http://www.guymacon.com/> says...
>
>> Oliver Betz wrote:
>>
>>>So why shouldn't the key be stored in this internal, more or less
>>>"protected" memory?
>>
>>Why encrypt then? Why not just store whatever you were planning
>>to encrypt in this internal, more or less "protected" memory?
>>The result is the same.
>
>I think he wants to encrypt it to protect it during the period
>from when it leaves his hands until it's loaded internally in
>the micro. Think of it as sneaker-ssl.

With the key already in the micro? That would work against someone
reading the downloadable/installable file. Not a bad idea.

There are two algorithms that are suitable for this, AES and RC4.
AES requires less RAM, RC4 requires less ROM and is a lot easier
for an embedded systems programmer to understand. Do a web search
on [ AES cipher ], [ RC4 Rivest ] and [ ciphersaber ].

I also suggest posting the code in sci.crypt before using it - but
make sure it is correct before swimming with the sharks!

(If anyone thinks that the encryption.decryption code should be
kept secret, please search on [ security obscurity cryptography ].)

--
Guy Macon <http://www.guymacon.com/>

From: Wim Ton on 16 Feb 2005 15:55
> LFSRs, maybe two combined, need close to nothing (RAM, ROM, time).
>
> What are the disadvantages?
>
> Oliver
> --
> Oliver Betz, Muenchen (oliverbetz.de)

You are right with the minimum resources and it surely will deter the mere
curious.

However, LFSRs need to be combined very carefully to be cryptographically
secure, mostly involving irregular stepping and majority and/or selection
funtions.

If you have 1 LFSR you need only the 'length' number of bits of know
plaintext to break the system.

To see what can go wrong with combining LFSRs, see the attacks on PKZIP and
GSM A5 (there is even a German 'Diplomarbeit' about it, althoug very
technical)

Regards, Wim


 |  Next  |  Last
Pages: 1 2 3 4 5
Prev: Keil C51/ 8051 port of uIP v0.9 TCP/IP stack.
Next: TCP/IP stack for GPRS