A Look at Public Key Encryption


Encryption is the process of disguising information by
transforming plain text into gibberish, or ciphertext, which
cannot be understood by an unauthorized person. Decryption is the
process of transforming ciphertext back into plaintext that can
be read by anyone. Example of encryption can be found in history,
for example in the era of the Cold War, the Solviet Union and the
United States would send electronic messages to one military
point to another, encrypted. If the enemy intercepted the
message, they would have to crack this message to get the
information. Typically when governments used encryption they used
a very complex method of encrypting messages. Encryption does not
have to be complex; the Captain Video Decoder Rings that we had
as children used encryption. You\'d encode your secret message,
such as "Meet me by the swings," by replacing the letters of the
alphabet with substitute letters from a certain number of places
away. For example, let\'s say we decide to use the key "+4." That
would mean we\'d switch each letter in our message with the letter
that comes four places later in the alphabet. D would become H; R
would become V, and so on. You, or anyone else who knows the key
can easily switch the H back to a D, the V back to an R, and
figure out where to meet. Theses two examples are on opposite
sides of the spectrum, but both have their similarities and their
differences.
The major difference complexity, the government pays
mathematicians to research complex algorithms by which to encode
the messages, like the system used by Captain Video but these
algorithms are complex enough that if you tried to crack them it
would take you decades with even the most powerful computer
today. This complex mathematical code is what makes the text
secure to anyone who tries to crack it. Some similarities we can
find in these two examples are their use of the key, the
unlocking instructions, to decode the message. They only used one
key to encrypt and decrypt the messages. This creates problems,
security problems. The single key must itself be kept very
secret, while somehow still being transmitted to the person
receiving encoded messages. Even if the key is transmitted
safely, which you can never know for certain, the recipient can
never be sure received messages haven\'t been intercepted by the
enemy, altered, and passed along to create havoc and disarray.
This was a major fault of the one key system that made it very
vulnerable. The answer to this problem can in 1976.
Up until 1976 no one outside the government or at least outside
the government\'s control, performed any serious work in
cryptography. The National Security Agency (NSA) was in charge of
all advancement of cryptography, and that changed when a 31-year-
old computer wizard named Whitfield Diffie came up with a new
system, called "public-key" cryptography.
Diffie tended a complicated multi-user computer system at
MIT. He became troubled with the problem of how to make the
system, which held a person\'s work and sometimes his or her
intimate secrets, truly secure. The traditional, top-down
approach to the problem- protecting the files by user passwords,
which in turn were stored in the electronic equivalent of vaults
tended by trusted system administrators- was not satisfying. The
weakness of the system was clear: The user\'s privacy depended on
the degree to which the administrators were willing to protect
it. Diffie recognized that the solution rested in a decentralized
system in which each person held the literal key to his or her
own privacy. He tried to get people interested in taking on the
mathematical challenge of discovering such a system, but there
were no takers. It was not until the early 1970s, when the people
running the ARPAnet were exploring security options for their
members, that Diffie decided to take it on himself. By then he
was at Stanford, under the thrall of David Kahn\'s work. The
problem with the existing system of cryptography was that secure
information traveled over insecure channels. In other words, a
message could be intercepted before reaching its recipient. The
passing of the key Kahn realized also was a major problem. The
problem got even worse when one tried to imagine encryption
employed on a massive scale. The only way to do it, really, was
to have registries, or digital repositories, where keys would be
stored. As far as Kiffie was concerned, that system was screwed,
you wound up having to trust the people in charge of the
registry. It negated the very essence of cryptography, to
maintain