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Encapsulating security payload

(also ESP)

Encapsulating security payload definition

Encapsulating security payload (ESP) is an encryption protocol that keeps data safe from unauthorized access. It's part of a group of security protocols called IPsec. ESP uses symmetric encryption, where the same key is used to both lock and unlock the data. It helps protect information by making it unreadable to anyone who shouldn't have access to it and ensures the data is genuine and hasn't been tampered with. Additionally, ESP helps prevent specific types of malicious attacks (e.g., replay).

See also: encryption key, replay attack

How does encapsulating security payload work?

  • When a device wants to send data to another device, ESP first encrypts the payload of the data packet. It uses cryptographic algorithms, such as Advanced Encryption Standard (AES), to scramble the data into an unreadable form. This encryption ensures that even if someone gets hold of the data, they cannot understand it without the decryption key.
  • ESP checks to ensure the encrypted data hasn't been tampered with by creating a unique digital signature. This signature acts like a fingerprint that the recipient can use to confirm if the data is real and hasn't been changed during transmission.
  • ESP encapsulates or puts the data inside a new package called an IP packet. This package has a special ESP header containing important details like encryption, authentication, and other necessary information for the recipient to understand and process the data correctly.
  • When the recipient device receives the encapsulated packet, it checks if ESP is being used by examining the header. It then decrypts the payload using the appropriate algorithm and verifies the data’s authenticity.
  • Once the recipient device has decrypted and verified the data, it can process the original payload as intended (e.g., deliver it to the appropriate application or service).