  We introduce LOCATHE (Location-Enhanced Authenticated Key Exchange), a
generic protocol that pools location, user attributes, access policy and
desired services into a multi-factor authentication, allowing two peers to
establish a secure, encrypted session and perform mutual authentication with
pre-shared keys, passwords and other authentication factors. LOCATHE
contributes to: (1) forward secrecy through ephemeral session keys; (2)
security through zero-knowledge password proofs (ZKPP), such that no passwords
can be learned from the exchange; (3) the ability to use not only location, but
also multiple authentication factors from a user to a service; (4) providing a
two-tiered privacy authentication scheme, in which a user may be authenticated
either based on her attributes (hiding her unique identification), or with a
full individual authentication; (5) employing the expressiveness and
flexibility of Decentralized or Multi-Authority Ciphertext-Policy
Attribute-Based Encryption, allowing multiple service providers to control
their respective key generation and attributes.
