Which device would you use to protect sensitive information in communications?

The use of a cryptographic device is essential for protecting sensitive information in communications because it encrypts data, making it unreadable to unauthorized users. This device transforms plaintext into ciphertext through various encryption algorithms, ensuring that even if the data is intercepted, it cannot be understood without the corresponding decryption key. This level of security is crucial in military and sensitive civilian communications to safeguard against espionage and unauthorized access.

In contrast, a signal booster is designed to strengthen the quality of a transmitted signal, but it does not provide any encryption or security for the data being transmitted. A router, while critical for directing traffic on a network, primarily focuses on data packet delivery rather than securing the content of communications. A multiplexer, on the other hand, is used to combine multiple signals for transmission over a single medium but does not add any layers of protection to the information itself. Thus, the cryptographic device stands out as the key tool for ensuring the confidentiality and integrity of sensitive communications.