* kB: the master key for data stored as "class-B", a 32-byte binary string.
* wrap(kB): an encrypted copy of kB. The keyserver stores wrap(kB) and never sees kB itself. The client (browser) uses a key derived from the user's password to decrypt wrap(kB), obtaining the real kB.
* sessionToken: a long-lived per-device token which allows the device to obtained signed BrowserID certificates for the account's identity (GUID@picl-something.org). This token remains valid until the user revokes it (either by changing their password, or triggering some kind of "revoke a specific device" or "revoke all devices" function).
= Test Vectors =