(ISC)2 Certified in Cybersecurity Practice Exam

What kind of encryption algorithm utilizes the same key for both encryption and decryption?

1. Symmetric encryption

2. Asymmetric encryption

3. Hashing

4. Steganography

The correct answer is: Symmetric encryption

The concept of using the same key for both encryption and decryption is characteristic of symmetric encryption. In symmetric encryption, both the sender and the recipient share a common key that is employed to encrypt the plaintext into ciphertext and then decrypt it back to plaintext. This method is efficient for both encryption and decryption processes, allowing for quick processing of large amounts of data. In practice, symmetric encryption algorithms like AES (Advanced Encryption Standard) and DES (Data Encryption Standard) function by relying on this shared secret key to maintain confidentiality. The primary challenge with symmetric encryption is the secure distribution of the key between parties, as anyone with access to the key can encrypt and decrypt data. Asymmetric encryption, on the other hand, uses a pair of keys – a public key for encryption and a private key for decryption, which is distinctly different from the symmetric method. Hashing transforms data into a fixed-size string of characters, which cannot be reversed back to the original data, and steganography involves hiding data within another medium rather than encrypting it. Thus, the correct understanding of symmetric encryption aligns it closely with the use of the same key for both the encryption and decryption processes.