How to disguise ciphertext If I want to have a secret conversation, then I can encrypt it (with OTR etc). However, since big brother watches all communication, sending encrypted data will likely raise flags. Does anyone know of an algorithm to take ciphertext and convert it into harmless looking plaintext?

For example, I could take each group of three hex digits, like "3E8" and convert it to an english word, like "peanut". So "2E8A983F7E100B6CE1" gets converted to "fork would said free dish quark". But I think that would still be pretty easy for big brother to detect.

Anyone know of a good algorithm for this? Anyone seen any research on it?

EDIT: Imagine two people want to communicate securely over a channel, but the channel only allows plaintext. If the channel doesn't understand the message, it will block it. So they have to find a way send a strong encrypted message that looks like plaintext.
What you are looking for is called steganography. It is a different field from cryptography so you might want to check in some other fora also.

I don't know much about steganography but i remember this paricular algorithm. You can take you ciphertext, and an image say a greyscale bitmap. Then you can replace the least significant bits of every pixel with a bit from your ciphertext. Since ciphertext are "random" bitstrings one would no be able to recognise a ciphertext from random noise on the pixel values.

You can then reconstruct the ciphertext by reading the last bit from each pixel.