The (Trusted) Timely Computing Base (T)TCB was developed by the Navigators team at the Faculty of Sciences of University of Lisbon, in Portugal.


The (T)TCB is free software, distributed under the GNU general public license. It can only be used for non-commercial purposes. Any modification to the source code must be made under the terms of this license. 


There is a mailing list for questions and discussions about the (T)TCB users. To subscribe to this mailing list please contact  requesting to join the list, or visit this link.

The (T)TCB is a distributed embedded component that provides a set of time and security related services to client applications: Timing Failure Detection of timed executions, Timely Execution of small functions, Duration Measurement of local or distributed computations, Trusted Random Numbers, and Trusted Block Agreement on a value with limited size. It can be used as a fundamental building block for the development of dependable real-time applications.

The classes of applications that can be addressed with the help of a (T)TCB include most soft or mission critical real-time applications, in particular fail-safe or QoS adaptive applications, and intrusion-tolerant (or Byzantine-resilient) applications.


The (T)TCB software is currently available for Real-Time Linux 2.0, WinCE 3.0 and for RTAI

The (T)TCB model and architecture is described in several papers, which you can retrieve through these pages. Other documents specifically concerned with the TCB software, including the user manual, are currently in preparation and will be available soon.


Work on the (T)TCB started  in the context of the MICRA and DEAR-COTS national projects, and continues in the MAFTIA and CORTEX european IST projects and in DEFEATS national project, where the TCB is being extended and applied to support the construction of dependable applications



Real-Time Linux is available at



RTAI is available at

optimised for

(C) 1999-2003, Navigators