Which of the following is NOT a characteristic of Public Key Cryptography?

Public Key Cryptography, also known as asymmetric cryptography, relies on a pair of keys: a public key and a private key. Each key performs a specific function in the encryption and decryption processes, allowing secure communication.

The choice stating that a public key database ensures third-party accountability of security is not a characteristic of Public Key Cryptography. While public keys can be stored and distributed through different means, such as certificates, the core functionality of public key cryptography does not inherently rely on a public key database for accountability. Accountability and security might be enhanced with proper key management practices, but these are not intrinsic to the public key system itself.

The other options illustrate key aspects of how Public Key Cryptography operates. For instance, the fact that a decryption key is never made public emphasizes the security model where only the intended recipient possesses the private key needed to decrypt. Guaranteeing that only the intended recipient can decrypt the message is a fundamental tenet of how asymmetric encryption secures communications. Furthermore, the ability to allow secure communication without pre-sharing a common encryption key highlights one of the attractive features of this cryptography method, enabling straightforward secure exchanges over insecure channels.