Cryptography

Introduction

The word cryptography in Greek means "secret writing." However, the term today refers to the science and art of transforming messages to make them secure and immune to attacks.

Figure shows the components involved in cryptography.

The original message, before being transformed, is called plaintext. After the message is transformed, it is called ciphertext.

An encryption algorithm transforms the plaintext to ciphertext; a decryption algorithm transforms the ciphertext back to plaintext.

The sender uses an encryption algorithm, and the receiver uses a decryption algorithm.