| ??? 05/09/05 13:11 Read: times |
#93219 - Re: to Dan Responding to: ???'s previous message |
Khaled Sarsam said:
I know about java but i find it difficult using usngined numbers. Unsigned numbers are 'easier' and more predictable (especially for shifting operations) that signed numbers. If you have already done so much about this XTEA encryption i would be glad if you could share with me your expertiese about the XTEA encryption. XTEA is a slight modification of TEA to deal with some weaknesses, but it still has some weaknesses that you should research to see if it fits your requirements for cryptographic strength. That goes for any cryptographic algorithm. XTEA can be operated in the same modes as DES. My difficult part to understand is the communication part, the data that is been sent to the microcontroller and interpereted as data-length, adress actual data checksum, etc, so that is my hard part. If you have the code room, sscanf() can help. For example, assuming your MCU has received a HEX record (line) into a char array named hex_record: unsigned len, addr, type; sscanf(hex_record, ":%2X%4X%2X", &len, &addr, &type); Now you have integer data objects you can use to scan and convert the rest of the HEX record. I found the assembly part in this site but i am not sure how to implement it within the microcontroller. The link I provided earlier has C source code for both TEA and XTEA (called "New variant"). You don't have to use assembly unless you've got some performance requirement that warrants it. Use C first to get your system prototyped, then optimize using assembly if necessary. |
| 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 |