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Adaptability is key to communications security

Peter Davies of Thales e-Security opines that one of the critical features for effective communications security is the ability to adapt equipment, since changes in algorithm, communications technology or techniques may lead to a need to upgrade the implementation standard.

September 10, 2002

The "electronic age" in which we exist is an increasingly complex combination of interacting applications, many of which have been written to take advantage of an immature technology in order either to give some dimly perceived competitive advantage or to fulfill a political imperative.

One consequence of this complexity has been to restrict the development of effective paradigms that would normally assist with the cultural dissemination of the problems associated with developing and maintaining an adequate security response. How can we instill a security ethic in our organizations when the threats are impossible for even specialists to characterize and therefore understand?

Peter Davies

The most effective strategy is to actively manage the complexity by dividing systems into two categories, those whose effectiveness is amenable to high standards of proof and those that are not.

Firewalls and intrusion detection systems are examples of security techniques that have no theory or practice associated with them that justifies us in believing that they will provide high levels of protection. The regular press reports of penetrations of what might rightly be supposed to be some of the most secure systems of this type in the world are evidence of this. To operate effectively, these types of solution require constant expert attention; you may be sure that the National Security Agency invests significant resource in the operation of these types of system.

Communications security by use of encryption, by contrast, is amenable to high standards of proof and relatively simple operating procedures. The techniques involved in analysis have been evolved over decades and are well understood by experts, providing cost effective protection where the implementation is of good quality. 

So what is a good quality implementation?

In the past, a good quality implementation involved equipment designed with very fixed functionality and many years behind the technological requirement. Nowadays, one of the critical features has become the ability to adapt the equipment, since changes in algorithm, communications technology or techniques may lead to a need to upgrade the implementation standard.

The rate at which cryptographic algorithms are being replaced is increasing rather than decreasing. Algorithms may be made obsolete as the result of degradation in resistance to brute force attacks over time, or due to a sudden and unexpected cryptanalytic success.

The need to replace algorithms is understood, but even so, in most security systems both the cost of upgrade and the time taken to achieve it will be enormous. As an example, the financial transactions industry is probably the biggest DES (Data Encryption Standard) user base and yet many systems are still only in the specification stages of a DES to Triple DES upgrade, with AES (Advanced Encryption Standard) as yet unplanned for.

The consequences of a flaw being found in a well-established algorithm may be extremely serious if there is no upgrade path for systems using it.

The large investment in operating security systems also brings with it the need for interoperability between new and "legacy" cryptographic equipments that can be many years old. A "big-bang" upgrade is often infeasible for practical and economic reasons; instead the gradual introduction of units that simultaneously offer support for current and legacy communication protocols and algorithms allows a controlled upgrade.

The underlying communications infrastructure over which a security product operates clearly affects the operation of that product. As upgrades to the communications infrastructure are required at an ever increasing rate, so too are upgrades to the cryptos that operate on them. A lack of available or upgradeable security products can act as a barrier to the uptake of improved communications capability.
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Communications is now a part of almost every environment, and communications security is an area in which both the nature and quality of the available security solutions are intelligible both by experts and by a wider population.

Segmentation of the communications security from the rest of the applications environment allows the techniques evolved over decades for analysis of these solutions to be deployed while at the same time permitting users to focus their risk-based analysis on areas that are not amenable to this type of "isolationism."

But to ensure that it is sensible and cost effective to use good quality implementations of these solutions to "lock down" certain elements of the overall solution, it is essential that the equipment used should bring a level of flexibility that will not deter unforeseen changes to aspects such as algorithms or protocols when required.

The author, Peter Davies, is technical director of Thales e-Security and has been active both in the UK and U.S. in the development of electronic security equipment for the government and banking sectors for the last 16 years.

Thales e-Securitysupplies cryptographic security products and solutions used to protect a range of critical information infrastructures. Operating in markets covering network and transaction security, Thales e-Security addresses the business security needs of corporations and governments alike. More than 20 governments and half of the world's banks, together with the majority of the busiest exchanges, currently use Thales e-Security technology. The company offers a range of solutions for the protection of data across a variety of Wide Area Networks, including dial-up, GSM, leased line, X.25, frame relay and IP networks.