Cryptography techniques

Cryptography is an art of codifying messages to avoid possible attacks. Sniffing, Spoofing and phishing are some common internet attacks. Attacks can be classified into two- Passive attack where attacker does not modify the contents of a message and Active attack where attacker modifies the content of the message. Cryptography is an efficient method to increase the security of messages where some codes are used to make message non-readable. The message in the non-readable format can be decoded by a technique, Cryptanalysis. The combination of Cryptography and Cryptanalysis is known as Cryptology. In the first step, plain text is converted into Cipher text, a codified text. For this we can employ two techniques- substitution techniques and transposition techniques. Caesar cipher, modified version of Caesar cipher, mono-alphabetic cipher, homophonic substitution cipher, polygram substitution cipher, poly-alphabetic substitution cipher, playfair cipher and hill cipher are examples for substitution techniques. Example for transposition techniques are Rail fence.