11. Introduction to Cryptography

Introduction to Cryptography

Cryptography is the art and science of securing information by converting it into a form that is unintelligible to unauthorized individuals. Its history dates back thousands of years, with the earliest instances found in ancient civilizations where secret codes were used to protect sensitive messages during wars and political communications. In modern times, cryptography has evolved significantly due to the rapid advancements in technology and the need for secure digital communication. It plays a crucial role in various aspects of our lives, including online banking, e-commerce, secure messaging, and data protection.

The primary goal of cryptography is to ensure confidentiality, integrity, and authenticity of information. Confidentiality refers to the protection of data from unauthorized access or reading by converting it into ciphertext, making it unreadable without the appropriate decryption key. Integrity ensures that the data remains unchanged during transmission or storage, preventing any unauthorized modifications. Authenticity involves verifying the identity of the sender and confirming that the received information indeed originated from the claimed source.

Modern cryptographic systems rely on complex algorithms and mathematical principles to achieve their objectives. Symmetric-key cryptography, where the same key is used for both encryption and decryption, is efficient for secure communication between trusted parties but requires a secure key exchange. Asymmetric-key cryptography, on the other hand, employs a pair of keys – a public key for encryption and a private key for decryption, enabling secure communication with anyone without the need for a secure key exchange. This combination of cryptographic techniques forms the basis for secure online communication and data protection, and it is an essential component of cybersecurity in the digital age.