Cryptography

Cryptography is a method of transmitting or storing secret messages where only intended recipient can read and process them. It is the science of writing in secret code and is an ancient art. It can be used to ensure Confidentiality, Integrity and Authenticity. The readable data(Clear Text/ Plain Text) converts into unreadable format(Cipher Text) using Encryption/Enciphering Algorithm. Encryption/Enciphering Algorithm is a set of rules dictating how enciphering and deciphering takes place. There are many types of algorithms. Blowfish, Des, Enigma, Gost, Loki97, ReipleDes, Xtea, etc.. There is a random variable called Crypto Variable/Key(a sequence of bits) which gives secrecy to the whole process. Only sender and the intended receiver should have the key. The intended recipient can Decrypt/Decipher using that Crypto Variable/Key.


Example:

Plane Text: The Technical Avenue
Algorithm: BlowFish
Key: 3

Cipher Text: 5T3jLYKbWglAp1S2cYGuVdTR1iMREeWt

The first documented use of cryptography in writing dates back to circa 1900 B.C. Julius Caesar developed a method of sending secret messages by substituting each letter in the message by a letter which is three positions ahead in the alphabet. (Rotation-3 or ROT-3 cipher)

Example:
Cipher Text: wkh whfkqlfdo dyhqxh
Key: 3
Plane Text: The Technical Avenue

 There are many more types of Cryptosystems available.
Vigenere Cipher, Vernam Cipher(One-Time Pad), Running Key Cipher, etc..

Encrypted messages can sometimes be broken by cryptanalysis, also called codebreaking, although modern cryptography techniques are virtually unbreakable.