Section: Application Domains

Safe Distributed Computations

Participants : Vincent Danjean, Thierry Gautier, Clément Pernet, Jean-Louis Roch.

Large scale distributed platforms, such as the GRID and Peer-to-Peer computing systems, gather thousands of nodes for computing parallel applications. At this scale, component failures, disconnections (fail-stop faults) or results modifications (malicious faults) are part of operation, and applications have to deal directly with repeated failures during program runs. Indeed, since failure rate in such platform is proportional to the number of involved resources, the mean time between failure is dramatically decreased on very large size architectures. Moreover, even if a middleware is used to secure the communications and to manage the resources, the computational nodes operate in an unbounded environment and are subject to a wide range of attacks able to break confidentiality or to alter the resources or the computed results. Beyond fault-tolerancy, yet the possibility of massive attacks resulting in an error rate larger than tolerable by the application has to be considered. Such massive attacks are especially of concern due to Distributed Denial of Service, virus or Trojan attacks, and more generally orchestrated attacks against widespread vulnerabilities of a specific operating system that may result in the corruption of a large number of resources. The challenge is then to provide confidence to the parties about the use of such an unbound infrastructure. The MOAIS team addresses two issues:

• fault tolerance (node failures and disconnections): based on a global distributed consistent state , for the sake of scalability;

• security aspects: confidentiality, authentication and integrity of the computations.

Our approach to solve those problems is based on the efficient checkpointing of the dataflow that described the computation at coarse-grain. This distributed checkpoint, based on the local stack of each work-stealer process, provides a causally linked representation of the state. It is used for a scalable checkpoint/restart protocol and for probabilistic detection of massive attacks.

Moreover, we study the scalability of security protocols on large scale infrastructures. To open the grid usage to commercial applications from small-size companies (namely in the field of micro and nano-technology within the global competitiveness cluster Minalogic in Grenoble), we are currently studying the scalability issues related to systematic ciphering of all components of a distributed application in relation with CS Group (thesis of Thomas Roche, CIFRE scholarship). Dedicated to multicore architectures, an adaptive parallelization of a block cipher (based on counter mode) has been evaluated. Within the SHIVA contract and the Ph.D. of Ludovic Jacquin (coadvised with the PLANETE EPI), we develop a high-rate systematic ciphering architecture based on the coupling of a multicore architecture with security components (FPGA and smart card).