Advanced Placement (AP) Computer Science

What is secret key cryptography?

1. A method using multiple keys to encrypt a single message.

2. A method where the same key is used for both encryption and decryption.

3. A technique used to delete data securely.

4. A process that involves hashing data for security.

The correct answer is: A method where the same key is used for both encryption and decryption.

Secret key cryptography, also known as symmetric encryption, is a cryptographic method where the same key is utilized for both the encryption and decryption of messages. This means that the sender and the intended recipient must both possess the key and keep it confidential to ensure the security of the transmitted information. This approach allows for efficient processing since only one key is needed, which simplifies the key management process under certain conditions. However, it also means that the secure distribution of this key is crucial, as anyone with access to the key can decrypt the information. Other methods, such as those that involve multiple keys or hashing data, do not align with the principles of secret key cryptography since they rely on different mechanisms for securing information. Hashing, for example, creates a fixed-size representation of data and is not reversible, which does not qualify as encryption.