I have long had this idea of a simple encryption that can be used during spoken conversations to communicate with someone without being understood by other people in the room. Is there anything like that?
The criteria are as follows:
- Does not have to be secure enough withstand anyone trying to crack it using a recording or other technical helpers
- Does need to be secure enough so that people cannot understand it on the fly
- Needs to be key-based so that there are enough keys that you wouldn't understand it without knowing the key, even if you know the encryption method
- There need to be enough possible keys so that you can't just guess the key
- Needs to be easy enough to encode/decode that you can do it in slow conversation speed if you trained enough for it
Is there anything like that? If not, is it at all possible?