I am new to cryptography. My questions is this: I process packets on runtime. I do not have time for advanced encryption or decryption techniques that take a long time.
As far as I know, going with OTP is the first option for this restriction. However, I also have another soft restriction which is this: I do not want to send keys that are as long as my messages. I can afford to produce long keys if I will only share a seed/ initialization vector between devices. However, in this case I have little processing power, so the generation of streaming keys should be as simple as possible.
What would be a good strategy in this case. I know that my terminology or understanding may be lacking; I can clarify or answer questions if you have.