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Sunday, March 25, 2007

Only NSA can listen, so that's OK

Export version of Lotus Notes provides trapdoor for NSA.

by Duncan Campbell (01.06.1999)


Giant US software manufacturer Lotus has been lowering the profile of information about how they have installed an NSA-only trapdoor into e-mail and conference systems used by many European governments, including the German Ministry of Defence, the French Ministry of Education and Research and the Ministry of Education in Latvia.

Last week in Brussels, Lotus staged a lavish "Global Government Forum" to try and gain more government customers for its software. They succeeded in striking a new 500,000 user deal with the Russian Ministry of Higher and Professional Education for the development of a new information infrastructure for the Russian education system. Yet another conference, Lotus Eurosphere '99, will be held in Berlin in October.

Lotus claims that its systems are inherently more secure than those from its main rival, Microsoft. However, although details of how the NSA trapdoor works can still be found in some corners of the web {1}, the key technical papers and press releases which reveal how Lotus worked with NSA to build a special trapdoor into the International Edition of Lotus Notes have disappeared from the web.

Visitors to the security pages on Lotus's website {2} are now told that the export version of Lotus Notes uses "a system approved by the US government called "Workgroup Differential" and "encrypt(s) information using 64 bit keys".

The name "Workgroup Differential" is meaningless. The correct title is "Differential Workfactor Cryptography". The "differential workfactor" means that the US National Security Agency can break the code on Lotus Notes private messages sixteen million times faster than anyone else.

How "Differential Workfactor Cryptography" works was revealed by Lotus itself three years ago. Although the documents concerned have now disappeared from the web, Telepolis has obtained copies.

In a keynote speech to the RSA Data Security Conference on 17 January 1996, Ray Ozzie, President of Lotus designers Iris Associates revealed how Lotus had come to terms with American government export controls, which prohibited the export of cryptographic systems with a key length over forty bits.

He told them that no-one regarded this as secure:

"Our customers have lost confidence in forty-bit crypto. They told us that, if we were going to continue to market forty-bit Lotus Notes overseas, we should stop marketing it as a secure system - that we should start to call it "data scrambling" or "data masking" instead of encryption."

Lotus's answer was a system that let NSA easily read foreign users' e-mail, while improving security against other eavesdroppers. In a paper distributed to the RSA conference, Security Project Leader Charles Kaufman explained in detail how the system worked.

When sending e-mail messages, Lotus uses a 64 bit key. But in export editions, 24 bits of the key are broadcast with the message, reducing the effective key length to forty bits. The 24 bits are encrypted using a public key created by the NSA. This is called the Workfactor Reduction Field. Only NSA can decrypt the information in the Workfactor Reduction Field. Once the key length is reduced to forty bits, fast modern computers can break the code in seconds or minutes.

Only Americans could think that this was an advantage for the Lotus system.

In 1996, Kaufman also revealed that Notes had to be weakened even further to prevent users from simply removing the NSA backdoor from being sent along with their messages. To prevent foreign users tampering with the workfactor reduction field, the International Edition of Lotus Notes will refuse to decipher any message which does not contain the correct field. To check this means that the entire key to the message has to be transmitted in the message. The recipient's software then checks that the workfactor reduction field is present and correct. The fact that the full key is sent along with the message creates the possibility of a second backdoor, reducing further.

Since these papers were presented openly, European governments have become aware of the enormous scale of communications monitoring by the NSA, and by the Echelon {3} network in particular. The loophole in Lotus Notes made front page news in Sweden in November 1997. Although the company did not deny the allegation, they claimed that the American government would not "misuse" them.

Since the row in Sweden, both Lotus and RSA have removed the 1996 papers from their web sites. Another Lotus employee claimed "we haven't weakened the security of international encryption, but actually made it equal to the US security (to everyone but the NSA). We are proud of this arrangement" (our emphasis).

Only Americans could think that this was an advantage for the Lotus system. From the European perspective, the greatest threat may be economic and political espionage by NSA. With Lotus bent on increasing its markets in Europe, there must be serious questions about whether users are being told the whole truth about security.


{1} See IBM Redbook, Page 80 at



Copyright (c) Heise Zeitschriften Verlag

Bill Totten


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