Secret codes and messages are and have always been an important part of politics, warfare, business and many other aspects of society. In the real world encryption in its various forms is the way to go when transmitting sensitive information. Today’s (real world) encryption methods are advanced enough that decrypting an intercepted message takes long enough that the actual information is useless by the time it can be read. Still, no encryption method is so advanced that it can’t be cracked, at least in theory.
Within modern cryptography the quantum computer is something of a big deal. In theory it would be able to crack any message encrypted with any currently known encryption method in a fraction of the time it would take with current methods. At least that’s how I remember it. It was a while since I was studying these things.
How would the existence of magic affect the science of cryptography?
Just like every living thing has a soul, so does every message have a meaning. The meaning is put into it when it’s created. Rewriting the message changes its meaning, but encrypting the message does not. What this means is that if you can extract the meaning of the message it doesn’t matter if it is encrypted or not. Of course, though not easily, the meaning of a message can be extracted through magical means.
A consequence of this is that any message that is intercepted can be read, no matter how sophisticated the encryption method is. There are a few ways of preventing this:
- Split up a message into smaller parts that don’t make sense on their own. That way if not every part is intercepted it will be that much harder making sense of the message.
- Make messages unreadable by anyone other than the intended recipient. Magically or mechanically sealed message containers or self-destructing documents.
- Make the message impossible to intercept. This may not be entirely possible.
- Any combination of the above.
I wrote somewhere else that the Aether effectively prevents high-speed internet (may not apply to optical cables) but there are other ways of transmitting data; radio, telephone, telegraph etc. These are all methods of communication that can be intercepted without detection (again, may not apply to optical cables). What’s more, telephone lines and radio waves can’t be magically shielded to prevent the messages they transfer from being read (or heard).
This doesn’t mean that encrypted messages aren’t transmitted over radio or telephone. Magecraft is rare and expensive and for most everyday needs plain old cryptography is enough to keep a message secret. Even if a message is intercepted, the one who snoops it is unlikely to afford magical decryption. In the unlikely event magical decryption is employed an extra layer of security can be added by splitting up the message in multiple smaller parts and adding some additional fake parts.
In wartime or during time of strained diplomatic relations the highest level of security may be needed. In these situations magic may be used for encryption and decryption.
Documents can be enchanted to hide any text written on them and to self destruct if the enchant is deactivated in the wrong way or by the wrong person. The same thing goes for message containers; magical and mechanical looks as well as protection against tampering. Enchanting a container to destroy its contents when tampered with or when opened by an unauthorized individual is also very much possible.
Finally, skilled messengers to carry the messages back and forth are also used when needed. This may not be as swift as transmitting via radio or phone, but the added security may very well be worth it.