Future Business Leaders of America (FBLA) Cybersecurity Practice Test

Which service does Authentication Header (AH) provide in IPsec?

1. Data encryption

2. Authentication of the sender

3. Compression of data packets

4. Data integrity verification

The correct answer is: Authentication of the sender

The Authentication Header (AH) in IPsec primarily provides the authentication of the sender, ensuring that the data is coming from a legitimate source. This is achieved by using cryptographic hashing methods to create a unique hash value for the packet that includes the header and data. When the recipient receives the packet, it can compute the hash value again using the same algorithm and compare it to the one sent; if they match, it verifies the sender's authenticity and confirms that the packet hasn't been tampered with. Authentication is crucial in securing communications, as it helps prevent unauthorized access and replay attacks. While AH does provide some elements of integrity verification, its primary function is to authenticate the sender, distinguishing it from other security functions such as data encryption, which is not a service provided by AH itself, or data compression, which is also outside its scope.