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Information security and cryptography are cornerstones of the information society.
In fact, strong security mechanisms are needed to implement functions such as
the integrity of financial transactions, the accountability for electronic signatures,
the confidentiality within a virtual enterprise, the privacy of personal information,
or the availability of the critical infrastructure.
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SINTRA, the Secure INtrusion-Tolerant
Replication Architecture, provides synchronization
and coordination of a distributed system in a secure and fault-tolerant way.
Replication is a proven way to enhance the availability of a component or a
subsystem. SINTRA provides replication at the level of services, by
distributing them on physically separate nodes linked by a wide-area network.
It is targeted at secure directories, the Domain Name System
(DNS), distributed file systems, and trusted security
services, which form the infrastructure for Deep Computing.
The protocols of SINTRA are secure and tolerate malicious insiders,
providing a correct service whenever a sufficient majority of the
machines is correct.
SINTRA uses the state-machine replication approach and provides several
coordination protocols like agreement and atomic broadcast. Such protocols are
well-known in environments with non-malicious faults, i.e., where crashes and
network packet losses occur. The novelty of SINTRA is to also tolerate
malicious actions originating within the system, such as nodes infected by
viruses.
SINTRA is targeted at services distributed over the Internet, like Grid
computing; it uses an asynchronous system model, which makes it by design
resilient against network outages or denial-of-service attacks. A number of
novel protocols for agreement and fault-tolerant broadcast are implemented in
SITNRA and have been demonstrated on the Internet for the first time. In
particular, SINTRA provides a practical protocol for randomized Byzantine
agreement and a new protocol for secure atomic broadcast. Cryptography, in
particular threshold cryptography, plays an important role in those protocols.
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