What does certificate pinning involve?

Certificate pinning is a security technique that enhances the confidence in the authenticity of a server's certificate by binding a specific certificate or public key to a particular client. In this context, option B accurately describes certificate pinning as it involves the client expecting a specific certificate when establishing a secure connection. This means that if a man-in-the-middle attack occurs, the malicious certificate presented would not match the expected certificate or public key that the client is 'pinned' to trust. Consequently, the man-in-the-middle certificate would be deemed untrusted, preventing a potential compromise of the secure channel.

The other options do not accurately represent the concept of certificate pinning. Allowing any certificate for inspection would contradict the safeguarding purpose of pinning, as it would introduce vulnerability. Automatic updates of certificates pertain more to maintenance rather than the strict usage and validation that pinning entails. Lastly, bypassing SSL inspection is the opposite of what certificate pinning aims to achieve, as it focuses on rigorous validation to protect against fraudulent certificates rather than evading security measures.