Practical problems with a cryptographic protection scheme

Abstract

Z is a software system designed to provide media-transparent net- work services on a collection of UNIX® machines. These services are comprised of file transfer and command execution; Z preserves file ownership on remote transfer, and more significantly, owner and group identity when executing commands remotely. In order to secure known vulnerabilities in the system, enhancements were made. In particular, a cryptographically-derived checksum was added to the messages. After the initial implementation of the checksumming scheme, several iterations of performance improvement occurred. The result was unsatisfactory to the user community, so the checksum was removed. Instead, vulnerabilities were reduced by improved monitoring and maintenance procedures.