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Authentication header

Authentication header

Authentication header definition

The authentication header (AH) is an Internet Protocol security (IPsec) suite component. We use it to provide connectionless integrity and data origin authentication for IP datagrams. AH also offers protection against replay attacks and ensures that no one changes the data during transit. Because of this, it is a crucial tool for maintaining the integrity and authenticity of information transmitted over IP networks.

See also: datagram, replay attack, packet capture, packet filtering

How do authentication headers work?

AH adds a header to the IP datagram (a data unit). This header contains information proving the integrity of the message and the sender’s identity. The sender creates a hash (a cryptographic checksum) using the original packet and a shared secret key. The recipient, using the same key, can then verify the hash to ensure the packet is authentic.

History of authentication headers

Authentication headers were created when the demand for secure transmission of information over the internet increased. AHs were developed as part of the IPsec protocol suite to address the issues of data tampering and spoofing in IP communications. It was gradually integrated into various network security architectures and VPN solutions.

Further reading

Ultimate digital security