I re-read the paper, and it’s true, the arguments they give are not mathematical in nature.
Page 11-13 (and the first line of page 14) basically runs down what’s wrong with having a key held in escrow by the government:
- If the key is ever disclosed, then every encrypted communication since that key was put into use becomes vulnerable. This is why big businesses are moving towards the practice of negotiating a new encryption key for every transaction, or forward secrecy.
- Encryption currently assures tamper-proofing as well as secrecy. Once you disclose the encryption key, you have no assurance that someone didn’t go in, make changes, and then re-encrypt the message.
- I’ll quote the last point in its entirety:
The third principal debate to third-party escrow is procedural and comes down to a simple question: who would control the escrowed keys? Within the US, one could postulate that the FBI or some other designated federal entity would hold the private key necessary to obtain access to data and that judicial mechanisms would be constructed to enable its use by the plethora of federal, state, and local law enforcement agencies. However, this leaves unanswered the question of what happens outside a nation’s borders. Would German and France public- and private- sector organizations be willing to use systems that gave the US government access to the data – especially when they could instead use locally built systems that do not? What about Russia? Would encrypted data transmitted between the US and China need to have keys escrowed by both governments? Could a single escrow agent be found that would be acceptable to both governments? If so, would access be granted to just one of the two governments or would both need to agree to a request?
So, yes, you’re correct. The main arguments are not with the math. However, I still equate the idea of a key that only the good guys can use with a unicorn that only approaches virgins: both ideas only make sense in a world with magic.
