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End-to-end Authorization

End-to-end Authorization

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End-to-end Authorization

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  1. End-to-end Authorization Jon Howell and David Kotz Presented by James Newell

  2. Background • Barriers impede authorization into hop-by-hop approaches • Administrative domains • Networks scale • Levels of abstraction • Different protocols • Gateways used to connect versions systems that bridge boundaries. End up making authorization decision on behalf of end-nodes.

  3. Motivation • End-to-end authorization approach spans all barriers • Make applications more secure • Reducing the number of programs that make access-control decisions • Giving more information to the access-control mechanisms • Providing more useful audit trails • Dynamic and Scalable Authorization

  4. Implementation • Snowflake • Built upon Simple Public Key Infrastructure (SPKI) • Principals, statements, and proofs are languages of the system • Statement is any assertion • Principle is any entity that can make a statement • Proof of authority is a collection of statements that together convince the reader of the truthfulness of the conclusion statement

  5. Signed-Certificate HD KS Transitivity HD KC·N Transitivity KS KC·N Name-monotonicity HKc· N  KC · N Signed-Certificate KS HKc· N Proofs • Send proof class to show authority • Transmitted in structure form • Proofs have expiration time • Structure of proof preserved (Tree)

  6. Prover • Tasks • Collects delegations in graph • Caches proofs • Constructs new Delegations • Graph • Nodes are principles and edges are proofs • Traverse graph breadth-first • Caches are “short-cuts” in the graph • Closures used to represent controlled principles

  7. Channels • Where authorization is propagated • Types • Secure network channel • Locally trustworthy channel • Signed request Client Server Channel with secret key KCH

  8. Secure Channel • Implementation of SSH with Java Sockets • Channel is a principle • Logic: • M  KCH K2  PC

  9. Local Channels • Trustworthy enough • No SSH channel • IPC pipes • No encryption in same JVM

  10. Signed Requests • Modified version of HTTP Authorization • Server’s Authenticate Message • Issuer that the client needs to speak for • Minimum restriction set • Client’s Authorization Message • Snowflake proof of the server’s message • Hash of the request • Server Authorization

  11. Applications • Web file server • Relational email database • Quoting protocol gateway

  12. Measurements • HTTP and RMI with Snowflake • HTTP and RMI with SSL • HTTP and RMI standard • Results • Major overhead on the order of many milliseconds with both Snowflake and SSL • Snowflake sometimes over two-times slower than SSL • Lack of performance may be due to slow libraries and no optimization

  13. Open Issues • Implementation issues (very abstract) • Performance is lacking • Does not address how logical assumptions are known to be true • How does administration work