[curves] PAKE use cases & requirements

[Feng Hao]

Hi Trevor,

>All Requirements
>-----------------
> - IPR free
> - security proof
> - efficient (in messages, computation)
> - simple
> - flexible to different curves
> - sidechannel resistant
> - no backdoors
> - small messages
> - non-augmented and augmented options
> - work with existing hashed passwords
> - low DoS potential
> - simultaneous initiate allowed

This looks good. I would suggest to change the third one to

 - efficient (in rounds, message, computation)

Then you don't need the last one, as the simultaneous initiation is related to the round efficiency.

Cheers,
Feng