Checking the integrity of trees

Abstract

We describe a general checking the integrity of data structures corrupted by memory faults. Our approach is based on a recursive checksum technique. Basic methods of using checksums have been previously seen to be useful for detecting faults at the bit or word level; among our results is their extension to the node level. The major contributions of our paper are threefold. First, we show how the recursive checksum procedure can be applied to tree data structures that are dynamically changing, whereas the previous work concentrated on trees that were static in their structure. This results in a asymptotic improvement in running time for applications where it; is natural to model the underlying data as a tree. Second, we present a C++ implementation of this scheme. Significantly, it is seen that our software can be used with existing applications which manipulate trees with only minor modification of the application programs. Finally, we have performed fault injection experiments which confirm the fault detection capability of our integrity checking approach.<>