Certified Information Systems Security Professional (CISSP) Practice Exam

The purpose of decryption in data communication is to convert cipher text back into plaintext. When data is transmitted over a network, especially sensitive information, it is often encrypted to protect it from unauthorized access. This encryption transforms the original readable data (plaintext) into an unreadable format (cipher text) using a specific algorithm and a key.

Decryption performs the reverse process, allowing authorized parties to convert the unreadable cipher text back into its original, readable form (plaintext). This is crucial for ensuring that the intended recipient can access and understand the information that was sent while keeping it secure from potential eavesdroppers.

The other choices pertain to different aspects of data communication security: securing transmission is related to encryption rather than decryption, converting plaintext into cipher text is the encryption process itself, and establishing a network connection has no direct relation to either encryption or decryption. Understanding the function of decryption is essential for grasping the overall mechanisms of secure communications in cybersecurity.