History of Cryptography

Cryptography has been used about 40 centuries ago by the people Egypt to send a message to the troops who were on the battlefield and to the message is not readable by the enemy, although the messenger captured by the enemy. Around 400 BC, cryptography was used by the Spartans in the form of a piece of papyrus or parchment covered with a wooden rod. In ancient Roman times, when Julius Caesar wanted to send a message secret to a general on the battlefield. Such messages should be sent by a soldier, but because it contains a secret message, Julius Caesar did not want to open the message in the middle of the road. Here Julius Caesar thinking about how to handle it is to randomize the contents of the message into a message that can not be understood by anyone but can only be Generals understood by all. Of the General had been notified earlier how to read the random messages, having learned key. In the second world war, German enigma machine or also called the rotor machine used by Hitler to send a message to troops on the battlefield. Germans really believe that the message is encrypted use can not be solved enigma.
But the assumption was wrong, after years of study and the allies had cracked the codes it. After the Germans know that the enigma can be solved, then the enigma has experienced several changes. German Enigma used to encrypt a message that has the possibility to be able 15'1018
decrypt the message. some historians believe that the end of World War II due to the Enigma encryption techniques solved.
The development of computer and communication systems in the 60's impact on the demand of certain parties as a means to protect information in digital form and to provide services security. Starting from Feistel of IBM's business in the early 70s and achieving
\ peak in 1977 with the appointment of DES (Data Encryption Standard) as a federal information processing standards of the United States to encrypt information that is not yet classified. DES is a cryptographic mechanism The most known throughout history. The most surprising development in the history of cryptography occurred in 1976 when Diffiel and Hellman published "New Directions in Cryptography". This paper introduces the revolutionary concept of public key cryptography, and also provides a new method for key exchange, security is based on
power discrete logarithm problem. although, Diffiel and Hellman not have practical realization of the idea of public key encryption that time, the idea is very clear and foster a broad interest in the cryptographic community. In 1978 Riv est, Shamir and Adleman discovered the design of public key encryption is now called RSA. Draft RSA factoring problem, based on hard numbers,

and reactivate efforts to find a more efficient method for factoring. 80 years of vast increases in these areas, the RSA system is still safe. Another system is the design of public key found by Taher ElGamal in 1985. This design based on discrete logarithm problem. One of the important contribution of public-key cryptography is a sign digital signatures. In 1991 the first international standard for digital signatures adopted. This standard is based on RSA public key design. In 1994 United States government adopted the Digital Signature Standard, a cryptographic mechanisms based on the ElGamal algorithm.

The Caesar's Cryptography

Caesar substitution:
Cryptography has been known since Roman times. Was a great king of the Romans at that time whose name was Julius Caesar who introduced the first cryptographic techniques. He used it to hide a secret letter he would send. If the couriers were arrested and the letter fell into the hands of the enemy then the Mush still can not get any information even managed to get a physical letter. Caesar cryptography technique is actually simple, namely by replacing each letter with another letter in the alphabet with the previous agreement. So Cesar and the recipients have made an agreement with a table - tables alphabetically between the original letter by letter instead. Here is an example of cryptographic Caesar.

Example, alphabetical table appointments as follows:

If you want to send a C-section the phrase: "WAR" then the contents of the letter is "DZI". While recipients will return to match sentences in the letter in the table and translated back so he could read the same sentence with what is going to be sent Caesar. While others who do not have the above table can not be read, so that security letter awake. It was said that Caesar's love letter to Cleopatra also uses cryptography so that it can not be known by the senate - the Roman senate who did not like his relationship with Cleopatra.

Cryptography techniques above Caesar substitution technique is also called a cesarean (Substitution Caesar) or substitution techniques. Cryptographic system is to survive long enough, but eventually can be solved. The simplicity of the encoding techniques into the basic technique of substitution is weakness. Enough with the technique Brute Force Attack, or even with just the trial error cryptographic encryption can be solved. By simply knowing what the letters out and then a lot of analysis. For example in the Indonesian language the letter 'A' appears at most, so if the letter is the letter 'Z' appears at most, it can be concluded that the letter 'Z' is a substitute letter 'A'. Once on the next to get a clear information.