Cryptography Reference
In-Depth Information
Though the test can be bypassed, utmost mistrust is recommended. Why was
such a test embedded in the first place without giving any warning? How many
more backdoors might there be in SESAME?
This discovery is shocking in view of the project's significance. I wouldn't
be surprised to hear one day that the designers caused the software's strange
behavior for lack of qualification.
Sending Passwords, and a Shocking Story
The examples given above are not exhaustive and basically nothing new for
cryptologists, and such a product is called
snake oil
. A 'more innovative' soft-
ware or hardware product would mix the password into the ciphertext in some
way or other. There are no limits to imagination. The bits can be hidden in the
header, or you somewhat 'extend' the ciphertext. Or you compress the cipher-
text to make plenty of room for sending the password along. In addition, the
vendor could encrypt the password together with a known sequential number
(using a fixed key) and mix the ciphertext created into the output. This makes
it extremely difficult for others to detect the fraud. Large-scale surveillance of
encrypted data communication would be easy in any event.
This fraud — you can't use a more harmless name — would probably not be
detected. Ask around how many users know about the ciphering in Microsoft
Word mentioned above. And yet, its 'quality' is easy to check. How much
harder would it be in the current example where fraud can hardly be proven
by analyzing the ciphertext alone!
However, the method has a disadvantage for the vendor: if a hacker eventually
succeeds in discovering this hide-and-seek game, fraud can no longer be denied.
Woe betide the vendor who is not the market leader!
There is a practical example for such an approach. During the preparation of
the second edition, I came across the text you will find in
txt/policy/madsen.txt
on our Web site. The author thinks this might be the biggest secret-service
scandal of the past century — but as often happens nowadays, most material
about it is found on the Internet.
In March 1992, the Iranian military counterespionage arrested Hans Buhler,
an honorable salesman of the Swiss firm Crypto AG, a leading supplier of
ciphering devices, accused of spying for Germany and the USA. Buhler was
interrogated for five hours daily for nine months, but he knew nothing about
backdoors allegedly built into the devices. Eventually, Crypto AG paid one
