What mechanism does IPsec use to establish a chain of authority?

IPsec, or Internet Protocol Security, relies on various mechanisms to provide secure communication over IP networks. One of the key methods it uses to establish a chain of authority is through digital signatures. Digital signatures help verify the authenticity of the communicating parties, ensuring that data has not been altered in transit and that it originates from a legitimate source.

In the context of IPsec, digital signatures play an essential role in the process of authentication and integrity verification. When a sender transmits data, they can generate a digital signature using their private key, allowing the recipient to verify the signature with the sender's public key. This process not only confirms the identity of the sender but also assures that the message has not been tampered with.

The other options, while important in their own contexts, do not directly relate to establishing a chain of authority in IPsec. Physical signatures are not utilized in digital communication; encryption keys are primarily associated with encrypting the data rather than establishing authority; and hashing algorithms are used for integrity verification but do not provide the same level of authentication as digital signatures. Thus, digital signatures are the mechanism that ensures a secure and trustworthy chain of authority within IPsec.