Quick Review of TCP and TLS Handshakes

Learn how devices establish trust and secure connections in the digital world.

Understanding the Handshakes by Travis Felder

In the world of cyber security, a handshake refers to the process of establishing a connection between two parties or devices as part of a secure communication protocol. A handshake typically ensures that both parties are aware of the connection and also serves to initiate the setup of a secure communication channel.

There are two common types of handshakes in cyber security:

• Three-Way Handshake
• Cryptographic Handshake

Three-Way Handshake (TCP Handshake)

In the context of a Transmission Control Protocol (TCP) connection, a three-way handshake is used to establish a secure and reliable connection between two devices. This process involves three specific steps:

• SYN: The initiating device sends a SYN (synchronize) packet to establish a connection with the receiving device.
• SYN-ACK: The receiving device acknowledges the SYN packet by sending back a SYN-ACK (synchronize-acknowledge) packet.
• ACK: The initiating device acknowledges the SYN-ACK packet by sending an ACK (acknowledge) packet.