Cryptography and Codes

Cryptography and Codes

“Unfortunately it can be easy for someone to get personal information through online shopping sites by using cryptography methods.”

The confidentiality of information is crucial for people, companies and countries. Cryptography develops methods of encoding and decoding information for its safety. Nowadays as people share their personal, commercial, military or political information in the internet cryptography is becoming more and more significant. Unfortunately it can be easy for someone to get personal information through online shopping sites by using cryptography methods. Therefore credit card information entered into the website is converted into illegible characters through an encryption method so that the credit card number can be transmitted to the server securely. Then the server can easily retrieve the original form of the credit card number using decryption. The encryption algorithm includes essential elements known as the “key”.  Protection of the “key” is always vital.

History of cryptography     

2000 BCE the ancient Egyptians used hieroglyphs on the gravestones of their kings. Since the system of hieroglyphs was too complex to understand, people began to use it for encoding. This was the starting point of cryptography. Roman emperor used a type of encryption technique called “Caesar cipher”. The Chinese people used ideography which conveys ideas through symbols by hiding the meaning of words. In the middle ages it prevailed in Europe. The Arabs were the first to succeed to decode encrypted messages like the Egyptian Ahmad al-Qalashandi which used the technique of language stability. With this technique the frequency of the characters within the encrypted text is compared to the frequency standards in the language. In this way it is determined what an encoded letter really stands for.   In 1931 the French obtained documents from a German spy which showed the functions of a code named enigma that was going to be used in world war 2 by the Germans. British mathematicians deciphered the code during the war thus the commands of Hitler could easily be learned by the allied powers.              

Cryptographic methods       

1.     Classical cryptography

2.     Modern cryptography

Classical cryptography is the replacement of a letter by another letter in the alphabet. For example TECHNO BLOG X=WHKKQR EORJ A       

SPARTAN CYLINDER is a device used in classical method. A message is written in a piece of paper rolled around a cylinder with a known diameter; the encrypted message is then detached from the cylinder and sent. The only way to DECHIPHER the code is having the same diametric cylinder. if the unrolled paper is rerolled around a decoding cylinder, the original message is obtained.    

 One Modern cryptography is called Public Key Cryptography. In this form the key used to encrypt the message is different from the one to decrypt it. The public key may be widely distributed while the private key is kept secret and only the possessor can decipher it.

Secret key cryptography is when a single secret key is used for encrypting and decrypting the code. One disadvantage of this cryptography is the distribution of the private key since it is always at the risk of being acquired by third parties.