You're technically right, but it's practically true for good algorithms. Yes, if you apply a rot(-13) before your rot(13) "encryption" it's going to make it wor

You're technically right, but it's practically true for good algorithms. Yes, if you apply a rot(-13) before your rot(13) "encryption" it's going to make it worse. I think that if we are going to be concerned about multiple layers of encryption, as you say, then we should be equally concerned with things such as what encoding we use to send text with, or whether we use gzip or bzip. It would suck having to worry about all that; good encryption algorithms work regardless of how their plaintext is encoded, and home grown encryption is just another form of encoding.