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It was in 1994 that the Data Encryption
Standard (DES), an American commercial encryption system,
was first cracked. The person who achieved this astonishing
feat was Mitsuru Matsui, a young engineer at Mitsubishi
Electric. But what attracted the attention of encryption
specialists around the world was not just the fact that
he had cracked DES but that he had used a completely new
technology to do it.
DES is an encryption technology with
a 56-bit key. At the time it was the most widely used commercial
cipher. Finding the correct key is like looking for a needle
in a haystack since there are 256 possible keys - that is,
there is a probability of just 1 in 70 quadrillion of picking
the right one by chance. Cracking such a code was considered,
for all intents and purposes, impossible.
First, there was the new methodology
employed for cracking DES. The linear decryption method developed
by Matsui was simply revolutionary: it greatly reduced the
number of calculations required for decryption. Of course,
there is a never-ending "arms race" between encryption
and decryption technologies: as soon as one side improves
its weaponry, so does the other to counter it. Cracking today's
cipher leads to the development of a stronger cipher tomorrow.
And indeed Mitsui's linear decryption method was to lead to
the birth of the strongest encryption system ever developed.
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Next, there was the new technology
to evaluate the strength of a cipher. Matsui was the first
person in the world to present a way to mathematically represent
the degree of difficulty involved in cracking a given code.
What this means is that everyone is free to choose an encryption
algorithm based on an objective appraisal of its merits. MISTY
thus transformed encryption systems into commercial products
that users can judge and pick for themselves. But that's not
all that's different. This commercial encryption technology
is taking on the role of a security infrastructure.
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