6-3-3 IPSec Explained

Key Concepts

• IPSec Overview
• Security Associations (SAs)
• Authentication Header (AH)
• Encapsulating Security Payload (ESP)
• Internet Key Exchange (IKE)

IPSec Overview

IPSec (Internet Protocol Security) is a suite of protocols designed to provide secure communication over IP networks. It ensures data integrity, confidentiality, and authentication by encrypting and authenticating IP packets.

Security Associations (SAs)

Security Associations are the foundation of IPSec. They define the security parameters for communication between two IPSec peers. Each SA includes information such as encryption algorithms, authentication methods, and key lifetimes. SAs are unidirectional, meaning two SAs are required for bidirectional communication.

Authentication Header (AH)

The Authentication Header provides data integrity and authentication but does not provide confidentiality. AH includes a hash value (MAC) that is computed over the entire IP packet, ensuring that the packet has not been altered in transit. AH is less commonly used than ESP due to its limitations in handling NAT (Network Address Translation).

Encapsulating Security Payload (ESP)

ESP provides both data integrity and confidentiality. It encrypts the payload of the IP packet and includes an authentication tag to verify the integrity of the encrypted data. ESP is more versatile than AH and is widely used in IPSec implementations.

Internet Key Exchange (IKE)

IKE is a protocol used to establish, negotiate, modify, and delete SAs. It uses a combination of ISAKMP (Internet Security Association and Key Management Protocol) and cryptographic algorithms to securely exchange keys and negotiate security parameters. IKE ensures that both parties agree on the same security settings before data transmission begins.

Examples and Analogies

Think of IPSec as a secure envelope for your letters. Just as an envelope protects the contents from being read by unauthorized parties, IPSec protects your data from being intercepted and tampered with.

Security Associations are like agreements between two parties on how to secure their communication. Just as you and a friend might agree on a secret code to communicate, IPSec peers agree on encryption and authentication methods.

The Authentication Header is like a seal on an envelope that ensures the contents have not been tampered with. If the seal is broken, you know the contents have been altered.

Encapsulating Security Payload is like a locked envelope that not only ensures the contents have not been tampered with but also keeps them secret. Only the intended recipient with the key can open and read the contents.

Internet Key Exchange is like a secure handshake between two parties to agree on the lock and key for their communication. Just as you and a friend might exchange keys to a lockbox, IKE ensures that both parties have the same security settings before exchanging data.