Which cryptographic concept uses keys that can be distributed openly and are used for encryption and decryption?

• A. Private Keys
• B. Public Keys
• C. Shared Keys
• D. Session Keys

Answer: (B)

Public-key cryptography uses a public key that can be distributed openly while the private key stays secret. Data encrypted with the public key can be decrypted only with the corresponding private key, and signatures created with the private key can be verified with the public key. This openness of the public key is what allows encryption and verification without sharing secret keys in advance. The other options don’t fit because private keys are kept secret, shared keys are used in symmetric encryption and must be shared securely, and session keys are temporary symmetric keys negotiated for a session.