Action Comte Concurrency, Mobility, and Transactions

1
Action ComèteConcurrency, Mobility, and
Transactions

• Catuscia Palamidessi
• INRIA-Futurs and LIX

2
Status and People

• Comète is an Action. We are planning to
  present it as a project in the next coming
  months.
• Permanent members
• Catuscia Palamidessi (coordinator)
• Fabrice Le Fessant
• Ongoing collaborations
• Frank Valencia, BRICS and Uppsala Univ.
  (Concurrent Constraint Programming, reactive
  programming, security)
• Diletta Cacciagrano, Univ. de LAquila
  (p-calculus, fairness)
• Planned collaborations
• Bernadette Charron Bost, LIX (Safety and
  liveness)
• Veronique Benzakem, LRI (Transactions)
• Giuseppe Castagna, ENS (Mobility)
• Davide Sangiorgi, Univ di Bologna (p-calculus)
• Vladimiro Sassone, Univ of Sussex and Michele
  Bugliesi, Univ di Venezia (distributed resources,
  atomicity. Possibility of a STREP)

3
Projects

• ACI Securite
• ROSSIGNOL Verification of Cryptographic
  Protocols
• LIF responsableD. Luigiez
• LSV Responsable F. Jacquemard
• INRIA-Futurs LIX responsable C. Palamidessi
• Verimag Responsible Y. Lackhnech

4
Main Goals

• Foundations of Langauges for Concurrent and
  Distributed Systems
• Process Calculi (pi-calculus)
• Mobility, Probabilities
• Development of a probabilistic version of the
  asynchronous ?-calculus
• Distributed implementation of the p-calculus
• A langauge for specification and verification of
  security protocols (PROPIS)
• Development of a platform for distributed
  programming

5
Main goals

• Probabilistic Asynchronous p (ppa)
• Aim add the power of randomization to obtain a
  language that
• is as expressive as p (it is possible to encode p
  into it)
• can be implemented in a fully distributed way
• Expressive power of p
• Solution to the generalized dining philosophers
• Encoding of p into ppa completed and proved
  correct wrt a notion of testing semantics

6
Features of PROPIS

• PRObabilistic PI for Security
• ppa enriched with cryptographic primitives
  similar to those of the spi-calculus Abadi and
  Gordon
• The probability features will allow to analyse
  security protocols at a finer level
  (cryptographic level), i.e. beyond the Dolew-Yao
  assumptions of perfect cryptography In our
  approach an attacker can try to guess a key, for
  instance. The point is to prove that the
  probability that his attack can be effective is
  negligible.
• The probability features will also allow to
  express protocols that require randomization.

7
Example The dining cryptographers
An example of achieving anonymity
Crypt(0)
pays0
notpays0
Master
Crypt(1)
Crypt(2)
8
The dining cryptographers

• The Problem
• Three cryptographers share a meal
• The meal is paid either by the organization
  (master) or by one of them. The master decides
  who pays
• Each of the cryptographers is informed by the
  master whether or not he is paying
• Goal
• The cryptographers would like to know whether the
  meal is being paid by the master or by one of
  them, but without knowing who is paying (if it is
  one of them).

9
The dining cryptographers Solution

• Solution Each cryptographer tosses a coin
  (probabilistic choice). Each coin is in between
  two cryptographers.
• The result of each coin-tossing is visible to the
  adjacent cryptographers, and only to them.
• Each cryptographer examines the two adjacent
  coins
• If he is paying, he announces agree if the
  results are the same, and disagree otherwise.
• If he is not paying, he says the opposite
• Claim 1 if the number of disagree is even,
  then the master is paying. Otherwise, one of them
  is paying.
• Claim 2 In the latter case, if the coin is fair
  the non paying cryptographers will not be able to
  deduce whom exactly is paying

10
The dining cryptographers Solution
Crypt(0)
pays0
notpays0
Coin(0)
Coin(1)
look20
Master
out1
Crypt(1)
Crypt(2)
Coin(2)