KeyNote Presentation KeyNote

Vishwas Patil, TIFR.2/10 KeyNote: “?”  Aim:- A notation for specifying local security policies and security credentials that can be sent over an untrusted network.

KeyNote Presentation Vishwas Patil, TIFR.3/10 KeyNote: versus PolicyMaker  KeyNote predicate notations are based on C-like expressions and regular expressions.  KeyNote assertions always return a boolean.  It has built-in credential signature verification.  Human-readable assertion syntax (RFC 822).  Trusted actions are described by simple attribute/value pair. But it is similar in spirit to that of PolicyMaker!

KeyNote Presentation Vishwas Patil, TIFR.4/10 KeyNote: Approach  KeyNote accepts as input a set of local policy assertions, a collection of credential assertions, and a collection of attributes ( action environment ) that describes a proposed trusted action associated with a set of public-keys.  By applying assertion predicates to the environment it decides consistency of actions with local policy.

KeyNote Presentation Vishwas Patil, TIFR.5/10 KeyNote: Architecture  KeyNote is monotonic; adding an assertion to a query can never result in a query's having a lower compliance value that it would have had without the assertion.  Removing an assertion never results in increasing the compliance value returned by KeyNote for a given query.  The monotonicity property can simplify the design and analysis of complex network- based security protocols.

KeyNote Presentation Vishwas Patil, TIFR.6/10 KeyNote: Architecture Continued  KeyNote does not itself provide credential revocation services.  KeyNote compliance checker helps in verifying (signature) the credentials received from untrusted requestor.

KeyNote Presentation Vishwas Patil, TIFR.7/10

KeyNote Presentation Vishwas Patil, TIFR.8/10 Keynote: Basic Syntax structure  A KeyNote assertion contains a sequence of sections, called fields, each of which specifies one aspect of the assertion's semantics.  Fields start with an identifier at the beginning of a line and continue until the next field is encountered. :: ? ? ? ? ? ? ; [X]* means zero or more repetitions of character string X. [X]+ means one or more repetitions of X. * means zero or more repetitions of non-terminal. + means one or more repetitions of X. ? means zero or one repetitions of X.  Nonterminal grammar symbols are enclosed in angle brackets.  Quoted strings in grammar productions represent terminals.  All KeyNote assertions are encoded in ASCII.

KeyNote Presentation Vishwas Patil, TIFR.9/10 KeyNote: Semantics  Informally, the semantics of KeyNote evaluation can be thought of as involving the construction of a directed graph of KeyNote assertions rooted at a POLICY assertion that connects with at least one of the principals that requested the action.  Semantics are almost similar to PolicyMaker.  RFC 2704 gives detailed description of the semantics.

KeyNote Presentation Vishwas Patil, TIFR.10/10 KeyNote: Discussion  Advantages / Disadvantages  Evaluation: simplicity, expressiveness, generality, extensibility  Open-Source implementations available.  OpenBSD uses it in IPSEC implementation.  $ man keynote