Malicious Cryptography: Exposing Cryptovirology

Chapter 4

The Two Faces of Anonymity

The ability to communicate anonymously and do things in an anonymous fashion is a mixed blessing. Criminals that perform criminal operations in an anonymous way minimize their risk of getting caught and voters that cast ballots anonymously do so without fear of persecution. Anonymity mechanisms, however simple in design, can be regarded as technologies unto themselves. The need for communicating anonymously and performing anonymous activities has extended into the digital realm and there currently exist advanced cryptographic algorithms for anonymously sending e-mails, voting, and purchasing items over the Internet. The potential for abuse of such technologies is immense and the first part of this chapter sheds some light on many of the possibilities. The chapter concludes with a description of a cryptotrojan attack that utilizes an anonymous communication channel. By carrying out the attack, the Trojan horse author is able to steal login/password pairs from a host machine in a way that greatly diminishes the risk of getting caught.

4.1 Anonymity in a Digital Age

Mechanisms that provide anonymity serve the common good in a variety of ways. For example, the ability to cast ballots anonymously helps protect voters against government persecution in response to their choices in electoral candidates. Other modes of communication that involve anonymity ...