FREE ESSAY ON CRYPTOGRAPHY

CRYPTOGRAPHY

Cryptography is the science of encoding a message into a form that is unreadable and
making sure only the proper people are capable of decoding the message back into its
original form. This is usually done by using an encryption algorithm and a decryption
algorithm (these two are often the same) and very often a secret key. Some of the early
cryptographic systems did not use a key but instead kept the algorithm itself secret. The
message sender uses the encryption algorithm and the key to encode the message, and then
sends it to the receiver. The receiver then uses the decryption algorithm and the key to
turn back the encrypted message into its original form and read it. 
If the message is intercepted others, they will only have unreadable data and will have
gained nothing, unless they can figure out the decryption algorithm and obtain the key.
This is why the key is never to be sent with the message, and has to be kept secret at
all cost. If the key is compromised, the sender and the encrypted data is no longer safe.
The sender and the receiver then usually agree on a new key to prevent any further
damage. 
In ancient Greece, around 550 Bc, messages were sent encoded to generals and could only
be decoded using special staff keys. The key actually consisted of a physical object,
which was applied on the message to get the decrypted version of it. In 50 Bc., one of
the most simple cryptographic algorithms ever used was the one called the Caesar cipher,
that was used by Julius Caesar to send messages to his generals. It consisted simply of
switching each letter with the letter that was 3 letters further down the alphabet. 
For example Stephen would become Vwhskhq. To decrypt the message, the receivers would
simply subtract 3 letters from each letter. This algorithm was later improved and called
ROT13, where the letters could be shifted to any number between 1 and 25, and the number
of letters shifted was the secret key. This very simple algorithm has been used on Usenet
successfully to prevent people from inadvertently reading materials they might find
offensive.
Monoalphabetic substitution is another simple step away from the ROT13 algorithm. In this
algorithm, each letter correspond to another letter but in no particular order. For
example a = d, d = x, f = e, etc for all 26 letters. This made it much harder to break
but also made fairly big keys that couldn't be memorized, since they consisted of 26
pairs of letters. 
In France during 1585, members of the king's court liked to send romantic or gossip
messages to each other and encrypt them for safety, which becomes almost a necessity.
Blaise de Vigenere came up with a poly-alpabetic substitution known as the Vigenere
cipher. Basically, the algorithm would encrypt messages several letters at a time instead
of letter by letter. For example ab = fh, th = sq. To simplify the huge keys it would
require, the key was broken into a table and a key, the table was fairly big but the key
was small enough to be memorized, and the table was useless without the key. This cipher
wasn't totally safe but no totally sure method to break it was developed before early in
the 20th century. 
During World War I, American troops used Native Americans to send messages over the
radio, which could only be understood by other native Indians, and almost nobody in
Germany could understand it. Also in World War I, the Playfair algorithm was developed by
the Allies, the key, like in the Vigenere cipher, is based on a little table and a short
keyword, which were both changed periodically. The rules used with the table were much
more complex and made it fairly safe. 
In World War II, however, the Germans gave up on abstract algorithms and came up with a
physical encrypting/decrypting machine called the Enigma. It had different wheels of
different sizes which were to be tuned differently depending on the date, the different
turnings were listed in a little booklet that came with the machine. It wasn't broken
before the Allies finally managed to capture enough pieces of the machine and collect
enough data from operating errors by the Germans. 
For most messages, computers would be the ideal carrier. Being able to encrypt our
messages so that no one else can read them is great, but is this something we really
need? Most of us do not need to have our transmissions encrypted, for the very simple
reason that nobody is interested in intercepting and reading the average person's things.

Privacy of this type would not be worth going through the trouble of setting up unless
you have an important secret to keep. However if it came standard with most operating
systems then it would be convenient enough to use on a regular basis. 
But there are people out there that need to keep important secrets and aren't terrorists
or criminals or the army. Most businesses will not be able to use the Internet as a means
of communication as long as all their online communications are vulnerable to industrial
spying. 
For businesses, the only safe way to communicate through a medium where each single bit
they send can be listened to is to encrypt all of their communications with a cipher
strong enough to resist breaking attempts from the other businesses. 
Another use of cryptography applied to business is the one used by a European television
channel. It distributes a keycode to their TVs, but only the customers paying every month
for the new keycode that corresponds to their decoder box will be able to decode the
broadcasted programs. Without the use of encryption, broadcasting a premium channel would
be stupid. 
Finally, one of the most useful uses of cryptography that we might all find useful is
"Digicash". Without cryptography it is very hard to implement a successful and convenient
scheme for online money. And online money is something most online businesses and
shoppers would love to have. 
Cryptography has its origins in wars and is therefore considered very much like a weapon
because of the advantage it can give to one side or the other. Legally, any information
about any kind of strong encryption is considered a weapon. What this means is that it is
illegal to export it to another country in any way. Many government agencies takes this
matter very seriously.
There are more or less equivalent laws in most other countries in the world as well.
Illegal immigrants in France tattooed cryptographic data on their forearms so that it
would be illegal to send them back to their country. 
Since the Internet is worldwide, posting any strong encryption information on the web is
the same as exporting it, and is therefore illegal. Which means that right now encrypted
Internet communications are more or less illegal as well. Also, the government is now
trying to impose the Clipper chip as a standard on all computers, and banning all other
forms of cryptography, in order to have a unique cryptographic system which it has the
ability to break. 
The problem is, is that it is already too late to prevent these cryptography systems from
being exported. Most foreign countries already have knowledge of them, and there are many
foreign business companies that use strong cryptography. So prohibiting exportation of
these materials is purely and simply useless. Furthermore, prohibiting US companies from
being able to export strong cryptography results in loss of marketing opportunities for
them. It also means that they won't be able to conduct safe, private conversations when
dealing with foreign companies because they cannot use encrypted communications.
Cryptography will prove to be important in the present and future by ensuring that credit
card numbers stay secure over the Internet. Other things it does is prevent fraud,
military actions are not compromised through bad radio security, and information
exchanged among the White House, Pentagon, and other governmental agencies are not
compromised by hostile nations.
Bibliography
Dont remember =(