Here's how I want encryption to work: it should be unbreakable when it's used to encrypt communication between journalists and their sources, but it should be b

Here's how I want encryption to work: it should be unbreakable when it's used to encrypt communication between journalists and their sources, but it should be breakable when used to encrypt communications between terrorists. I really "want [this thing] to be true". So why doesn't it work like this?