* randomly choose a 32-byte srpSalt (unique, but not secret)
* create srpVerifier from srpPW and srpSalt (as described below)
* deliver (email, stretchParams, mainSalt, srpParams, srpSalt, srpVerifier) to the keyserver's "POST /account/create" API
The server, when creating a new account, creates both kA and wrap(kB) as randomly-generated 256-bit (32-byte) strings. It stores these, along with all the remaining values, indexed by email, in the account table where they can be retrieved by getToken later.