Keeloq Encoder example code

[Ioannis]

Thanks Richard for the effort on this.

I'll try to do the same on the encryption part which is what I am interested in.

About PBPL, sure I will try to do this in PBP since the code is inteded to run on a low end PIC.

Thanks again,
Ioannis

[richard]

I feel there is something missing here , the code is meant to be rolling encryption . so something needs to be saved for the next call doesn't it ?

[Ioannis]

The general idea from the limited data I could find is this.

You have your secret keys (8 bytes) that both the encrypter and decrypter know.

Then you have also 4 bytes of data (32 bits) that will be encoded byt the encoder (either hardware or software).

The result will be placed (after the crazy 512 shifts and rotatons) at the same registers of the 4 data bytes. They call it CSR3:CSR0 registers in the data sheet and ANs.

Regarding the decryption I am very close, almost working. But the Encoder is a bit harder to accomplish, mainly because resources are limited on a 12Fxxx chips.

Thanks,
Ioannis