Primitives for identity and authorization

 Libtrust is library for managing authentication and authorization using public
 key cryptography.
 .
 Authentication is handled using the identity attached to the public key.
 Libtrust provides multiple methods to prove possession of the private key
 associated with an identity.
 .
  - TLS x509 certificates
  - Signature verification
  - Key Challenge
 .
 Authorization and access control is managed through a distributed trust graph.
 Trust servers are used as the authorities of the trust graph and allow caching
 portions of the graph for faster access.