Lawful Interception and Countermeasures : In the era of Internet Telephony

University essay from KTH/Kommunikationssystem, CoS


Lawful interception and the way it is performed have played a significant role in the effectiveness of this type of communication monitoring. Although the secrecy of interception and the related equipment are supposed to provide correct information to a law enforcement agency, there are some countermeasures that can be taken by the subject that can seriously undermine the collection of correct and accurate data.

This thesis project attempts to identify the problems that exist for interception of telephony (be it fixed, mobile, or via the Internet). Moreover, there are some suggestions for improvements how lawful interception should be performed in order to avoid possible attacks that could decrease the credibility of the intercepted data. Numerous publications (in print or distributed on the Internet) have described weaknesses in the current state of the art lawful interception when using equipment that can be purchased in the market. This thesis presents improvements in how LI can be conducted in order to avoid these vulnerabilities. Additionally, there is a description of the key escrow systems and the possibility of avoiding one of their most significant vulnerabilities.

The main problem of the lawful interception is the rapid changes in telecommunications and the complicated architecture of the telecommunication networks, as both make monitoring vulnerable to specific countermeasures. An analysis of how lawful interception can take place and current countermeasures for lawful interception of Internet telephony are vital in order to identify the problems in carrying out such intercepts today and to make suggestions for improvements.

This topic is especially relevant given the current Swedish “FRA lagen” regarding interception of electronic communication going into, out of, and through Sweden. Not only is it important to understand how lawful interception can be performed or prevented, but it is also important to understand how information obtained from lawful interception could be purposely misleading or falsified.

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