(ISC)2 Certified in Cybersecurity Practice Exam

What process is used to convert ciphertext back into plaintext?

1. Encoding

2. Decryption

3. Hashing

4. Encoding

The correct answer is: Decryption

The process of converting ciphertext back into plaintext is known as decryption. In cryptography, when data is encrypted, it is transformed into an unreadable format called ciphertext using an algorithm and a key. This ensures that unauthorized individuals cannot easily access the original information without proper authorization. Decryption is the reverse process of encryption, where the ciphertext is transformed back into its original, readable form—plain text—using a corresponding key and decryption algorithm. This is essential for secure communications, allowing authorized users to retrieve and understand the information that has been previously secured. Encoding does not serve the same purpose as decryption, as it involves transforming data into a different format for the purpose of data integrity and transmission, rather than for secrecy. Hashing, on the other hand, produces a fixed-size string of characters from input data and is primarily used to verify data integrity, not to convert ciphertext back into plaintext. The repetition of "Encoding" in the options does not alter its function, showing no relevance to the task of decryption.