Introduction to Lawful Interception Systems

A lot of people are asking me about Lawful Interception Systems, so I had the idea to present some basic concepts about this technology here.

Introduction

Lawful interception is the legally sanctioned official access to private communications, such as telephone calls, e-mail messages, instant messages or VOIP communications. In general, LI is a security process in which a network operator or service provider gives law enforcement officials access to the communications of private individuals or organizations.

Architecture

Although the details may vary from country to country or vendor to vendor there are a general set of logical and physical requirements wich explain much of the common terminology used. The architecture requires a distinct separation of the IP network and the networks used for distribution and processing of LI information. The interfaces between the production network and the Law Enforcement System must be protected.

Basically a LI system must have a set of components (it may vary)

• Capture System - Normally a appliance with High Speed Network Capture Cards designed to receive 100% of a link traffic (using taps), analyze it and send the desired info (monitored people conversations) to the Mediation System;
• Mediation System - A system designed to act as a standard of input/output interfaces standardizing the data collection when several communication systems from different vendors are in place 
• Data Retention System - A secured storage system which stores all the captured data and allows only LEA (Law Enforcement Agencies) to access it (a carrier or an enterprise deploying cannot have access to captured data)
• Administration System - Usually a GUI that allows only LEA to access it and input all the necessary information for data capture

Types of Captured data

With LI systems is possible flows from applications like:

• emails;
• instant messengers chats;
• voip talks;
• web pages "hidden content";
• web chats,
• IRC's

etc...

Regulations

To avoid fraud or abuse some regulations are in place to protect the right of individuals and organizations.

• CALEA - http://www.askcalea.com
• ETSI - http://portal.etsi.org/li/Summary.asp

Summary

Several government agencies around the globe are deploying LI systems. Carriers are doing this also to be compliance with local regulations. There are several studies about privacy, criptography but these are beyond the scope of this post.

Regards

Comments

[Dave]

I think that it is also important to point out here that many of these systems require the law enforcement organization to acquire the appropriate level of legal authorization to be in place before any data capture can take place.

Additionally, it is also important to note that the strength of the data collected hinges on the organizations capability to establish non-repudiation. Tomes of incriminating data can be turned useless if the target of the investigation can repudiate the data.

[Douglas Alvarez]

This is an emerging market segment - especially in Latin America - and it is very hard to establish a true picture of the market needs for now. I myself have done some research on various LA countries laws and regulations with no luck or at the most poor or incomplete information.

For solution providers, such as the company I work for, the main topic is to offer a low cost, out-of the box solution as this represents an extra cost for the operators that must implement such type of solution.