Key verification is the process of confirming that a cryptographic key really belongs to the expected person, device, or service. In secure messaging and other encrypted systems, this check helps users and software confirm identity, not just protect data. A key can be valid cryptographically and still belong to an attacker if the connection has been redirected or replaced.
This matters because many attacks target trust instead of encryption itself. In a man-in-the-middle attack, for example, an adversary can try to present their own key while pretending to be a legitimate contact. Verification methods such as safety numbers, fingerprints, code comparisons, or automatic checks help detect these mismatches. Good key verification reduces the chance of silent impersonation and supports end-to-end encryption by making sure the right keys are tied to the right parties.