Encapsulating Security Payload (ESP)

Also known as: ESP

ESP is a member of the IPsec protocol suite and provides origin authenticity through source authentication, data integrity with hash functions and confidentiality through encryption protection for IP packets. ESP operates directly on top of IP, using IP protocol number 5.

Authentication Headers (AH) can be used in place of ESP. However, AH protocol provides a mechanism for authentication only. ESP provides data confidentiality (encryption) and authentication (data integrity, data origin authentication, and replay protection).