Three-Way Handshake

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Three-Way Handshake

The Three-Way Handshake is a network protocol mechanism that involves the exchange of three messages between two hosts to establish a secure and reliable communication channel. Each message confirms the receipt of the previous message, ensuring a synchronized start to data transmission.

What does Three-Way Handshake mean?

Three-Way Handshake refers to a communication protocol that establishes a secure communication channel between two parties over an untrusted network. It is a fundamental mechanism in network security, providing confidentiality, authentication, and data integrity.

The handshake consists of three distinct messages exchanged between the parties:

  1. Client Hello: The client initiates the connection by sending a ‘client hello’ message. This message contains the client’s randomly generated nonce (a unique number to identify the Session) and a list of supported cryptographic algorithms.

  2. Server Hello: The server responds with a ‘server hello’ message. It selects a cryptographic algorithm from the client’s list, generates its own nonce, and sends a certificate containing its public key.

  3. Client Key Exchange: The client uses the server’s public key to encrypt a secret key and sends it to the server. This key will be used for encrypting the subsequent communication.

Applications

Three-Way Handshake is widely used in secure communication protocols, including:

  • Transport Layer Security (TLS) / Secure Sockets Layer (SSL): Used for securing web browsing, email, and other internet connections.
  • Internet Key Exchange Protocol (IKE): Used for secure key exchange in VPNs and IPsec.
  • Secure Shell (SSH): Used for secure remote access and File Transfer.
  • Virtual Private Network (VPN): Used for creating encrypted connections over public networks.

Its importance lies in establishing secure communication channels, preventing eavesdropping, man-in-the-middle attacks, and data tampering.

History

Three-Way Handshake was developed in the early days of computer networking. In 1976, Roger Needham and David Schroeder proposed a protocol for secure communication using public-key cryptography. This protocol paved the way for the modern Three-Way Handshake.

In 1996, the Transport Layer Security (TLS) protocol was developed by Netscape. TLS incorporated Three-Way Handshake as a fundamental component for secure web browsing. Over time, Three-Way Handshake became widely adopted in other protocols due to its proven security and efficiency.

Today, Three-Way Handshake remains a cornerstone of secure communication, ensuring data privacy, authentication, and integrity in various technology applications.