I have only recently become interested in encryption, and know very little about the various technologies currently available. The following question is therefore likely naive: Is there any strong form of encryption that allows you to specify both the input and output? For example, suppose I want to encrypt "This is an encrypted message" to send to a friend. Now, the standard form of PGP takes this text and transforms it into code that looks random, and it occurs to me that anyone who intercepted this message would be able to tell that it was encrypted. Could it be possible for someone to specify both the text to be encrypted and the encoded version so as to make the encrypted version appear to be unencrypted to the man in the middle, e.g. "This is an encrypted message"--->"This is an unencrypted message"? It seems that this would be a very useful tool. Thanks for your thoughts!