[messaging] Pour one out for "voice authentication"

[Jeff Burdges]

An important question here is : 

What happens if users attempt to communicate the information before explaining it’s purpose aka foreshadowing?

Algorithm : 
- Let Words() be a function that returns a list of dictionary words, and ideally corresponding images, based upon a sha256.  
- Assign the two parties roles named Alice and Bob based upon the session information.
- Let X be the session information, let X_a = sha256("Alice" + X), and let X_b = sha256(“bob” + X)
- Alice's device tells her to communicate Words(X_a) in the conversation, and expect Bob to communicate Words(X_b).  
- Bob’s device does the same swapping X_a and X_b.

Both devices explain that : 
- the words should be used or foreshadowed in the conversation in close proximity in a context that makes using another word difficult,
- ideally any variation in the order in which they appear in the conversation should be explained later, and
- Alice and Bob should discuss when they think they’ve finished the exchange, citing when they believe referenced the words in the conversation.

Example : Alice does not need to say openly that her fist word is elephant, but could instead mention seeing a zoo animal eating hay in a strange place, and then elaborate later in the conversation.  Alice could foreshadow the appearance of an elephant in the conversation. 

There is an issue here merely the appearance of words in the conversation is not enough because our hostile AI could insert words where they only kinda make sense, like adding “like an apple” onto a sentence that trailed off.  That’s why we ask that the words all be foreshadowed in close proximity, and then later discuss that part of the conversation that contained the key exchange.  

We’ll eventually have AIs who could defeat such a key exchange of course, but at the same time some humans are extremely witty, so the risk of exposure for an attacker could be kept high.  Also, wit might remain pretty hard for machines to grasp for quite some time, partially because industry probably lacks the economic incentives to dump a bunch of resources into understanding wit. 

Jeff