Vol. 10, No. 6, Page 7

TECHNICAL EVALUATION - SAFEWORD

fingerprint has not changed. There are two such software packages

for PCs on the market:

DATA PHYSICIAN (Digital Dispatch Inc, US), designed to detect and remove Data Viruses from protected programs (reviewed in the February issue of Computers & Security).

VACCINE (Sophos Ltd, UK) detects Computer Viruses, Trojan Horses and Logic Bombs in any system, as well as checking the system against possible corruption or data modification. (CFSB will feature a review of VACCINE in a forthcoming issue - Editor).

Dr Jan Hruska, Sophos Ltd, UK

Product: - SafeWord: user identification. Developer:- Enigma Logic Inc, California, USA. Vendor:- SCICON Ltd, Wavendon Tower, Wavendon, Milton Keynes MK17 8LX, UK; tel: 0908-585858.

Availability:- Many different systems, including IBM MVS and VM running VTAM; UNIX; Tandem; DEC VAX running VMS or ULTRIX; XENIX; and MS-DOS. Contact SCICON for full details.

Price:- Typically f120-f175 per user.

This month's technical evaluation is slightly different as it does not concentrate on one specific version of a product. This is for the good reason that SafeWord is available on many different systems. Indeed, this is its main strength.

SafeWord provides a system of user-identification and audit. Each authorized user must carry a small key which is approximately the same size as an ordinary car key but squarer in shape. The key is designed to fit onto a key-ring. Each SafeWord key contains a proprietary microchip that not only stores the encryption key for use by the encryption algorithm, but is also capable of performing the encryption. The physical key must be inserted into a SafeWord decoder to be used. The decoder (which can be shared by multiple users) is a small handheld calculator comprising a six-button numeric keypad and an LCD display. There is no physical connection between the decoder and the computer system with which it is being used. Both the key and the decoder are claimed to be tamper-resistant, although no details were available to confirm the level to which this was carried out.

Access to a system by an authorized user is granted if the user can present the correct response to a random number challenge generated by SafeWord software running on the protected host system and displayed on the user's terminal screen. After identifying himself with his PIN, the user types the random number challenge into the decoder. Using the cryptographic key stored within the physical key, and a cryptographic algorithm, the decoder can calculate a response to the random number challenge. This response is shown on the LCD display of the decoder. The

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Vol. 10, No. 6, Page 8

user types the response into the computer system, and if all is well, access is granted.

Note that this process checks the user (he must know his

PIN), the key (it must be inserted into the decoder), and the data held within the key which is used in the cryptographic process described above. The critical part of this whole process is how the cryptographic keys held within the user's physical key are managed. For small numbers, each physical key is initialized by the manufacturer. Previous technical evaluations have pointed out the glaring weakness of this process, that someone (or some object) at the manufacturer's site potentially has knowledge of the cryptographic key. This objection is removed by the availability of SafeWord's key management package to the end user, and the many different authentication devices (see below). The security officer can set up his own keys with no outside knowledge by any third party. Like all the good things in life, this is not free.

Anyone implementing SafeWord to deter all unauthorized users has to make SafeWord software available on the machine in question. The software is written in C, which, allowing for the vagaries of some C compilers, is about as portable as you can get, given the upsurge in the use of C in the last few years.

It has to be said that none of the above is particularly unique. Other systems on the market require a user to prove his identity by entering a secret PIN, and to prove possession of a security key (it must be inserted into the decoder for access to succeed). However, SafeWord stands out as being available on almost any computer you care to name. This will be important in companies where many different systems are in routine use.

SafeWord software is also capable of operating with many of the security authentication devices currently available. This includes such names as Atalla Confidante (for ANSI X9.9 authentication equipment), Watchword and SecurID. The advantage of this to the user is that no matter what hardware proves ideal at the user interface, it is always possible to use SafeWord software on the computer which is being protected. Only one implementation is necessary.

SafeWord has been validated by the US National Computer Security Centre. In layman's terms, this means that security experts in the US have gone through the product very carefully and found nothing amiss. Note that this process only validates the functionality of the product, not the cryptographic algorithm in use.

Security management facilities are suitably extensive. User access can be regulated by combinations of time, date, ID, communications port, and total number of accesses. An audit trail is maintained on system disks in encrypted form. Only an authorized security officer can decrypt the audit trail. The management functions seemed particularly easy to use; options are chosen from data displayed on the screen relevant to an individual user.

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Vol. 10, No. 6, Page 9

Security against an external attacker monitoring traffic between a user and a remote computer is ultimately reliant on the strength of the encryption algorithm in use. Two options are

available, an in-house proprietary algorithm, or DES. In the past year there has been much discussion of proprietary algorithms, including the exposure by Martin Kochanski of many systems using unforgivably weak algorithms. Details of the proprietary algorithm used in SafeWord are not available, but it is stated to be subject to a current upgrade. Because of Martin Kochanski?

The developers are to be congratulated for reacting in this

way, rather than following the path trodden by other companies (who had better remain nameless) of trying to brush off serious attacks on algorithm strength as inconsequential.

I have commented in many previous technical evaluations that even if you know the details of the algorithm, there is no unique way to prove that an algorithm is strong. By comparison, proving an algorithm weak is simply a matter of compromising it in some way. SafeWord offers a DES option. Stick to it if you can, to guarantee some level of integrity.

So far I have concentrated on access control. However the same process of offering a random number challenge and verifying the response as being from the correct user with the correct key, can be used from within any software executing on the computer protected by SafeWord. Perhaps the best analogy to this is that of a "lock". Software locks can be used where necessary, and can be implemented in a hierarchical manner, so that more than one user is involved. I will be dealing with this in a future technical evaluation which will concentrate on a particular implementation of SafeWord: PC-SAFE, which is a version of SafeWord protecting a PC.

Conclusion

There are competing products offering similar facilities to SafeWord. However, I do not known of a product that is available on such a large range of systems. Potentially, any computer which offers a C compiler can be protected. Operation is also possible using a wide range of security hardware. These seem to be the two strong points of SafeWord.

Anyone implementing SafeWord can purchase a key management package. This is the only way to program keys for yourself so that no component of the key used by the encryption algorithm is inserted by either the manufacturer or his agent. Such a course of action is to be recommended to all purchasers. Likewise, unless performance parameters unavoidably dictate otherwise, stick to the DES algorithm.

SafeWord is implemented as a software package. The structure of the package is claimed to be designed to deter attackers, but as with all software packages, it can be circumvented by attacking the computer on which the software is executing.

Think of the case of a personal computer, where an attacker has secretly attached a logic analyser to the processor. Such an instrument is capable of monitoring all aspects of processing.

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Vol. 10, No. 6, Page 10

This includes the cryptographic keys and the cryptographic algorithm. This is not a criticism unique to SafeWord - similar scenarios apply to many computers that implement their security entirely in software.

However, it is undeniable that a tamper-resistant hardware security unit can cause a bottleneck, and would remove many of the claims to operate on many different systems in many different configurations. It all boils down to whether you are trying to prevent attacks by outsiders or attacks by internal staff. Against the latter, software security packages do not provide an answer, and there is no real alternative to wrapping up the security functions within tamper-resistant hardware. SafeWord can of course be run within tamper-resistant hardware.

There are components of any security system on which you must rely for security to be maintained. You must trust the supervisor on a mainframe system. All the security files are protected by access only being available to anyone with supervisor privileges. All this pre-supposes that there are no covert methods of gaining supervisory access. On a microcomputer you must prevent a potential attacker monitoring the processor with a logic analyser, or other similar instrument. This relies on physical security measures.

If you want your computer systems to be available only to authorized users, and especially if you have many different types of computer to which the user has legitimate access, then you could do far worse than look at SafeWord.

Keith Jackson

NORWEGIAN MANAGERS Top management within Norwegian corporate circles "care NEGLECT CONTINGENCY little or nothing" about safeguarding company computer systems PLANNING against natural or man-made catastrophes or subsequent losses

incurred through down-time, according to a new report presented to both industry and government by the Norwegian software systems organization, Informatikk A/S. The report runs to over 130 pages and covers a wide brief including Norwegian corporate attitudes to new technology and the relationship between computer departments and management thinking.

The report found that eight out of 10 managing directors were "100% aware" of the implications should the company face a computer failure. "Most managers agreed that computers are at risk and a smaller number accepted that their companies were almost dependent on computer efficiency to support the smooth running of their businesses. The most common answer to the question, "Why haven't you adopted an emergency contingency plan?" was that management didn't have the time to either develop or implement such a safeguard, according to the report.

The Informatikk report's researchers interviewed corporate and technical managers from 50 medium- to large-sized Norwegian companies with annual net sales of US$32 million to US$800 million. The company in each instance was asked by the research

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