How can I build raspberry pi that will encrypt calls on my phone (say lets VoIP calls, as cellular ones are harder but still an option). The rasp Pi would need to be connected in-between my earphones and my iPhone. There seems to be a product that tried to do this and launched on kickstart but they seem defunct now (https://www.kickstarter.com/projects/620001568/jackpair-safeguard-your-phone-conversation). I cant seem to figure it out whether theyre defunct because of lack of demand or due to product not working well.
You want to scramble your voice before it's sent through the phone? In this case you'll need a descrambler on the other end, and the quality will probably suffer since voice codecs are lossy and you'll have to account for that in your algorithm.<p>It sounds like a fun project but practically speaking why not just use some end-to-end encrypted VoIP protocol? The only practical use case I can see for your solution would be to do it over normal GSM calls when you don't have a data connection. Then it could have some value.