Encyclopedia of Cryptography and Security

2005 Edition
| Editors: Henk C. A. van Tilborg

Trojan Horses, Computer Viruses and Worms

  • Yvo Desmedt
Reference work entry
DOI: https://doi.org/10.1007/0-387-23483-7_438

A program which is different from the specified (specs) one, is said to contain a Trojan horse. The Trojan horse may be malicious. It is difficult to decide whether a program is free of Trojan horses.

A Trojan horse that, when executed, can modify other computer programs, e.g., by copying itself (or a part of it) into these, is called a computer virus. Protection mechanisms used against {computer viruses} are to:
  • use digitally signed computer programs. Provided these digitally signed programs were developed in a secure and trusted environment, then one can detect modifications to the digitally signed program [3]. (For implementation issues see [1].) If the environment was not trusted, known computer viruses may be in the digitally signed program and remain undetected unless virus scanners are used.

  • use virus scanners. To a known computer virus corresponds a fingerprint(also known as a “signature” in the computer virus literature). Before running a program (e.g., at the start-up of...

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  1. [1]
    Davida, G.I., Y.G. Desmedt, and B.J. Matt (1989). “Defending systems against viruses through cryptographic authentication.” Proceedings 1989 IEEE Symposium on Security and Privacy, IEEE Computer Society, May 1989, Oakland, CA, 312–318.Google Scholar
  2. [2]
    Hoffman, L.J. (ed.) (1990). Rogue Programs: Viruses, Worms and Trojan Horses. Van-Nostrand Reinhold, New York.Google Scholar
  3. [3]
    Pozzo, M.M. and T.E. Gray (1987). “An approach to containing viruses.” Computers and Security, 6 (4), 321–331.CrossRefGoogle Scholar
  4. [4]
    Shoch, J.F. and J. Hupp (1982). “The `worm' programs: Early experience with a distributed computation.” Communication of ACM, 25 (3), 172–180.CrossRefGoogle Scholar

Copyright information

© International Federation for Information Processing 2005

Authors and Affiliations

  • Yvo Desmedt

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