here is a video link to a lecture given by M. Castro on the topic of Byzantine fault tolerant systems. If reading the papers is a daunting task for somebody, this is an interesting alternative for sure.
University of Washington
April 6, 2000
Miguel Castro, Massachusetts Institute of Technology
The growing reliance of our society on computers demands that we provide systems with improved reliability, availability, and security. This talk describes BFT -- a new software Byzantine fault tolerance toolkit that addresses these issues. BFT can be used to build replicated systems that work correctly and remain available even when some of their replicas behave arbitrarily due to malicious attacks, software errors, or hardware failures.