Knowledge transfer and information leakage in protocols Abdullah - PowerPoint PPT Presentation

Knowledge transfer and information leakage in protocols Abdullah Abdul Khadir, Madhavan Mukund, S P Suresh Chennai Mathematical Institute {abdullah,madhavan, spsuresh }@cmi.ac.in Formal Methods Update Meeting IIT Mandi July 18, 2017 Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 1 / 15

• Structured conversation to efgect information exchange • Informative : Transmit relevant information to trusted partner • Safe : Do not leak confjdential data to eavesdropper(s) • Full safety not always possible. e.g. rejecting a password • Quantify information leakage Information exchange in protocols Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 2 / 15 • Protocols

• Informative : Transmit relevant information to trusted partner • Safe : Do not leak confjdential data to eavesdropper(s) • Full safety not always possible. e.g. rejecting a password • Quantify information leakage Information exchange in protocols Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 2 / 15 • Protocols • Structured conversation to efgect information exchange

• Safe : Do not leak confjdential data to eavesdropper(s) • Full safety not always possible. e.g. rejecting a password • Quantify information leakage Information exchange in protocols Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 2 / 15 • Protocols • Structured conversation to efgect information exchange • Informative : Transmit relevant information to trusted partner

• Full safety not always possible. e.g. rejecting a password • Quantify information leakage Information exchange in protocols Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 2 / 15 • Protocols • Structured conversation to efgect information exchange • Informative : Transmit relevant information to trusted partner • Safe : Do not leak confjdential data to eavesdropper(s)

• Quantify information leakage Information exchange in protocols Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 2 / 15 • Protocols • Structured conversation to efgect information exchange • Informative : Transmit relevant information to trusted partner • Safe : Do not leak confjdential data to eavesdropper(s) • Full safety not always possible. e.g. rejecting a password

Information exchange in protocols Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 2 / 15 • Protocols • Structured conversation to efgect information exchange • Informative : Transmit relevant information to trusted partner • Safe : Do not leak confjdential data to eavesdropper(s) • Full safety not always possible. e.g. rejecting a password • Quantify information leakage

• Low outputs not afgected by high inputs • Quantitative : Measure information leakage based on entropy Studying information leakage Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 3 / 15 • Qualitative : Non-interference and allied notions / refjnements

• Quantitative : Measure information leakage based on entropy Studying information leakage Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 3 / 15 • Qualitative : Non-interference and allied notions / refjnements • Low outputs not afgected by high inputs

Studying information leakage Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 3 / 15 • Qualitative : Non-interference and allied notions / refjnements • Low outputs not afgected by high inputs • Quantitative : Measure information leakage based on entropy

• Information consists of propositional facts • Represents knowledge to be shared among agents • Eavesdropper has no knowledge initially • As messages are exchanged, agents learn more facts • Measure how much eavesdropper knows at the end • Check if honest agents know all they ought to know Our approach Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 4 / 15 • Discrete measurement of information leakage

• Represents knowledge to be shared among agents • Eavesdropper has no knowledge initially • As messages are exchanged, agents learn more facts • Measure how much eavesdropper knows at the end • Check if honest agents know all they ought to know Our approach Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 4 / 15 • Discrete measurement of information leakage • Information consists of propositional facts

• Eavesdropper has no knowledge initially • As messages are exchanged, agents learn more facts • Measure how much eavesdropper knows at the end • Check if honest agents know all they ought to know Our approach Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 4 / 15 • Discrete measurement of information leakage • Information consists of propositional facts • Represents knowledge to be shared among agents

• As messages are exchanged, agents learn more facts • Measure how much eavesdropper knows at the end • Check if honest agents know all they ought to know Our approach Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 4 / 15 • Discrete measurement of information leakage • Information consists of propositional facts • Represents knowledge to be shared among agents • Eavesdropper has no knowledge initially

• Measure how much eavesdropper knows at the end • Check if honest agents know all they ought to know Our approach Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 4 / 15 • Discrete measurement of information leakage • Information consists of propositional facts • Represents knowledge to be shared among agents • Eavesdropper has no knowledge initially • As messages are exchanged, agents learn more facts

• Check if honest agents know all they ought to know Our approach Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 4 / 15 • Discrete measurement of information leakage • Information consists of propositional facts • Represents knowledge to be shared among agents • Eavesdropper has no knowledge initially • As messages are exchanged, agents learn more facts • Measure how much eavesdropper knows at the end

Abdullah, Madhavan, Suresh Our approach Knowledge transfer and information leakage in protocols Update Meeting 2017 4 / 15 • Discrete measurement of information leakage • Information consists of propositional facts • Represents knowledge to be shared among agents • Eavesdropper has no knowledge initially • As messages are exchanged, agents learn more facts • Measure how much eavesdropper knows at the end • Check if honest agents know all they ought to know

• The deal • Find a sequence of (truthful) announcements that help them learn the whole deal, while D does not know the whole deal SADI problems A 0 1 B 2 3 4 C 5 6 7 8 Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 5 / 15 • There are four agents A , B , C and D , with D being the eavesdropper

• Find a sequence of (truthful) announcements that help them learn the whole deal, while D does not know the whole deal SADI problems A B C Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 5 / 15 • There are four agents A , B , C and D , with D being the eavesdropper • The deal 0 , 1 2 , 3 , 4 5 , 6 , 7 , 8

SADI problems A B C while D does not know the whole deal Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 5 / 15 • There are four agents A , B , C and D , with D being the eavesdropper • The deal 0 , 1 2 , 3 , 4 5 , 6 , 7 , 8 • Find a sequence of (truthful) announcements that help them learn the whole deal,

• What is known at the end? • Can this be promoted to a protocol? • Yes! Informative and safe sequences A My hand is 01 or 08 or 18 B Pass C My hand is 0234 or 1237 or 5678 Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 6 / 15 • A one-round protocol

• Can this be promoted to a protocol? • Yes! Informative and safe sequences A My hand is 01 or 08 or 18 B Pass C My hand is 0234 or 1237 or 5678 Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 6 / 15 • A one-round protocol • What is known at the end?

• Yes! Informative and safe sequences A My hand is 01 or 08 or 18 B Pass C My hand is 0234 or 1237 or 5678 Abdullah, Madhavan, Suresh Knowledge transfer and information leakage in protocols Update Meeting 2017 6 / 15 • A one-round protocol • What is known at the end? • Can this be promoted to a protocol?