Which statement about public-key cryptography is true?

Which statement about public-key cryptography is true?

• A. It uses a single key that everyone must know to encrypt and decrypt.
• B. It uses a pair of keys, a public key for encryption and a private key for decryption.
• C. It relies on a hardware device to perform all encryption.
• D. It uses a pair of keys, but only the private key is ever used for encryption.

Answer: (B)

Public-key cryptography relies on two keys that work together. A public key is shared openly and used to encrypt messages, while a private key is kept secret and used to decrypt them. This separation means anyone can send you a confidential message by encrypting it with your public key, and only you can read it with your private key. It also allows digital signatures, where you sign with your private key and others verify with your public key. The idea of a single key known by everyone would expose the content to anyone, so that’s not correct. Hardware requirements aren’t what define this concept—the essential point is the key pair. Encryption is done with the public key, not the private key.

Public-key cryptography relies on two keys that work together. A public key is shared openly and used to encrypt messages, while a private key is kept secret and used to decrypt them. This separation means anyone can send you a confidential message by encrypting it with your public key, and only you can read it with your private key. It also allows digital signatures, where you sign with your private key and others verify with your public key. The idea of a single key known by everyone would expose the content to anyone, so that’s not correct. Hardware requirements aren’t what define this concept—the essential point is the key pair. Encryption is done with the public key, not the private key.