Analog Audio Signal Crypting

[fairplay]

Hi,
I wanna ask some questions to you. I have a project for my highschool. Thanks for your help.

Project Details:
First step, we wanna convert analog audio signal to digital signal. After we will change a few bite (i am not sure that. i wanna say: 1/8 of byte) so it will be crypted. Finally, we will convert crypted digital signal to analog audio signal and give PIC's output. This analog data will send on unreliable point and another PIC will decrypt this signal with use reverse this method.

Questions:
How many bite of every digital audio sample is enough? 8 bite are enough? We wanna write this program with PIC assembly. We can't use ready encoder part on this project cause it must be changeable. We don't have enough information about this project.

Sorry for my bad English, thanks.

 

[KrisBlueNZ]

I'd say you'll need to encode every bit of every byte. Look for public domain encryption systems and pass the digitised data through it just like it was a file. The encrypted data will be uncompressable so you'll need plenty of bandwidth between the sending PIC and the receiving PIC. If the communication is unreliable (you said it will be sent "on unreliable point"; I don't know what you mean exactly), you'll need error correction and/or error detection and retries. Also it may not be possible to do it in real time; this depends on how complicated the compression and transfer algorithms are, and how fast your processor is. There are super-fast PIC-compatible processors available (not from Microchip;.sorry I've forgotten the name of the company - Google it). Good luck!

 

[fairplay]

I have only usb brenner pic programmer tool. It is mean, i can only code microchip basic pic products. We don't work industrial. So we can't have every pic and programmer tool. We are just student. It should has a basic way. When understand, when making.

Thank you for your help.