| ??? 05/04/05 06:11 Read: times |
#92859 - for the xor method to work Responding to: ???'s previous message |
You xor the data byte with a byte from a random number generator which has been seeded with some value.Then to decode it again you xor each byte of the recieved encrypted data with a byte from the random number generater seeded with the same value as the encryption rng.Its the simplest symetric method avialable and provides only the simplest protection which can be defeated with a pencil and paper within about 5 minutes.AES and DES may be small in terms of code size but the are slow in software.It you want a conpromise between the xor method and the slowness of DES/AES then go for RC4,it has known weakness but nothing which is going to matter in your application and it can be implemented in hardware quite easily.contact me if you want vhdl code which will implment it in a cpld.
Jez jez-smith@lycos.co.uk |
| Topic | Author | Date |
| ISP-AES(or other tiny encryption)for LPC | 01/01/70 00:00 | |
| so it works? | 01/01/70 00:00 | |
| re so it works? | 01/01/70 00:00 | |
| could it be | 01/01/70 00:00 | |
| TEA | 01/01/70 00:00 | |
| re could it be? | 01/01/70 00:00 | |
| double-xor | 01/01/70 00:00 | |
| LPC935 | 01/01/70 00:00 | |
| TEA | 01/01/70 00:00 | |
| Tea time! | 01/01/70 00:00 | |
| TEA time ;) | 01/01/70 00:00 | |
More tea | 01/01/70 00:00 | |
| Please clarify requirements | 01/01/70 00:00 | |
| what i want, Dan | 01/01/70 00:00 | |
| Looks like you are set then | 01/01/70 00:00 | |
| to Dan | 01/01/70 00:00 | |
| Re: to Dan | 01/01/70 00:00 | |
| Mode of operation | 01/01/70 00:00 | |
| I underdstand now., thanks | 01/01/70 00:00 | |
| better done in hardware | 01/01/70 00:00 | |
| what about this? | 01/01/70 00:00 | |
| what are you making | 01/01/70 00:00 | |
| theft has to be prevented | 01/01/70 00:00 | |
| either or | 01/01/70 00:00 | |
| FM is just a "vehicle"... | 01/01/70 00:00 | |
| but a diesel | 01/01/70 00:00 | |
| it's easy | 01/01/70 00:00 | |
| again, why | 01/01/70 00:00 | |
| unsecure? | 01/01/70 00:00 | |
| yes | 01/01/70 00:00 | |
| Individual sector security bits removal | 01/01/70 00:00 | |
| lockbits | 01/01/70 00:00 | |
| Now i understand! | 01/01/70 00:00 | |
| same thing | 01/01/70 00:00 | |
| what am i making? | 01/01/70 00:00 | |
| be careful | 01/01/70 00:00 | |
| why GSM? | 01/01/70 00:00 | |
| FM | 01/01/70 00:00 | |
| FM | 01/01/70 00:00 | |
| for the xor method to work | 01/01/70 00:00 | |
| RC4 | 01/01/70 00:00 | |
| RC4 | 01/01/70 00:00 | |
| A reminder | 01/01/70 00:00 | |
| encryption | 01/01/70 00:00 | |
| pgpi.org | 01/01/70 00:00 | |
| ok thanks jez | 01/01/70 00:00 |