Abstract :
Security in networks differs in several aspects from security in a centralized computer system. This is because (1) the switching nodes and concentrators are distributed physically and cannot be considered secure, and (2) the network protocols, if not properly designed, can be used by an intruder to gain access to the network data or have it misrouted. This special issue describes many developments in the above-mentioned aspects of data security in networks. The first article surveys digital signatures. Both private-key and public-key encryption techniques can be used to generate digital signatures. Since an unauthorized party can counterfeit public keys or use private keys that have been compromised, the use of public-key encryption alone does not ensure secrecy or a correct digital signature. The next article discusses the protection of public keys and signature keys. A protocol is a set of rules to be followed by users to ensure orderly communication. The next work describes several issues in protocol design and implementation. The importance of arbitrators in the design of secure protocols is explained and some implementations are described. An application of the RSA digital signature to electronic mail is described in the last article.
