Which mechanism is designed to bind a client’s credentials to a TLS session to reduce the risk of MITM?

Which mechanism is designed to bind a client’s credentials to a TLS session to reduce the risk of MITM?

• A. HSTS
• B. HPKP
• C. Token Binding
• D. TLS Channel Binding

Answer: (C)

Token Binding is designed to bind a client’s credential, such as a token, to the TLS session with the server. By attaching a binding to the TLS connection, the client proves possession of the credential only within that specific session, and the server can verify that the credential is tied to the exact TLS channel being used. This means an attacker who intercepts the credential cannot replay it on a different connection or against a different server, because the binding to the TLS session is missing or invalid for them. HSTS only enforces HTTPS for future requests, not binding credentials to a session. HPKP pins server keys to prevent forged certificates, which helps with trust in the certificate chain but doesn’t bind client credentials to a TLS session. TLS Channel Binding can tie an authentication step to the TLS channel, but Token Binding provides the explicit mechanism for binding tokens to the TLS session, making it the best fit for reducing MITM risk in this scenario.

Token Binding is designed to bind a client’s credential, such as a token, to the TLS session with the server. By attaching a binding to the TLS connection, the client proves possession of the credential only within that specific session, and the server can verify that the credential is tied to the exact TLS channel being used. This means an attacker who intercepts the credential cannot replay it on a different connection or against a different server, because the binding to the TLS session is missing or invalid for them. HSTS only enforces HTTPS for future requests, not binding credentials to a session. HPKP pins server keys to prevent forged certificates, which helps with trust in the certificate chain but doesn’t bind client credentials to a TLS session. TLS Channel Binding can tie an authentication step to the TLS channel, but Token Binding provides the explicit mechanism for binding tokens to the TLS session, making it the best fit for reducing MITM risk in this scenario.