CRYPTOGRAPHY

CRYPTOGRAPHY

ABSTRACT:

In the olden days, messages had to be conveyed during wars to instruct troops to carry out certain battle plans. As there were no modern communication devices then like the satellite and telephone, generals had to depend on messengers on horseback to deliver the messages. The danger was that the rider could easily be intercepted on his way to deliver the message, making it possible for the enemy to know where the opposing troops were located and how to ambush them. This would make it easy for them to be able to defeat their opposing army easily.

To counter such a consequence, Julius Caesar (who was believed to pioneer cryptography) invented a code language called the Caesar cipher. It was an easily broken code, but in a time where cryptography was unheard of, it became a major factor in him winning his wars. The Caesar cipher worked simply by shifting the letters in the alphabet by an arbitrary number of positions by the setter of the code. The receiver, having already known the number of positions the letters were shifted, would just as easily shift the letters back and retrieve the original message. For example, “The river flows” became “uif sjwfs gmpxt” if all the letters were shifted by one.

The proliferation of computers and communications systems in the 1960s brought with it a demand from the private sector for means to protect information in digital form and to provide security services. Beginning with the work of Feistel at IBM in the early 1970s and culminating in 1977 with the adoption as a U.S. Federal Information Processing Standard for encrypting unclassified information, DES, the Data Encryption Standard, is the most well-known cryptographic mechanism in history. It remains the standard means for securing electronic commerce for many financial institutions around the world. The most striking development in the history of cryptography came in 1976 when Diffie and Hellman published New Directions in Cryptography. This paper introduced the evolutionary concept of public-key cryptography and also provided a new and ingenious method.

Cryptography is a field of science involved with the encryption and decryption of data such that when a data is encrypted with a password, it is rendered unreadable or completely unusable until it is decrypted by either the same password or another of a suitable nature. It would be preferable that the password for decryption be held only by the intended viewers such that the encrypted data becomes completely secure and is only accessible to those who are supposed to access it. Without the correct password for decryption, a hijacker is unable to use the encrypted data in any way whatsoever unless he manages to crack the algorithm used to encrypt the data. Strong algorithms will require hundreds or thousands of years with current hardware to crack while the weakest ones take average hardware slightly over a few seconds to break

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