CEH Practice Question: Advanced Topics: Wireless, Cloud, IoT, Cryptography
A company wants to ensure that data in transit between its IoT devices and the cloud server is encrypted. Which protocol combination is BEST suited for this purpose?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
MQTT with TLS
The best choice for encrypting data in transit between IoT devices and a cloud server is MQTT with TLS. MQTT is a lightweight, publish-subscribe protocol ideal for IoT, and TLS provides robust encryption. While CoAP with DTLS is also secure, it is typically used for constrained device-to-device communication, not as the primary protocol for cloud connectivity. HTTP with SSL is too heavy for many IoT devices, and MQTT without encryption lacks security. Therefore, MQTT with TLS is the optimal combination.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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MQTT without encryption
Why it's wrong here
MQTT without encryption is fundamentally insecure for data in transit, leaving sensitive information vulnerable to eavesdropping, tampering, and unauthorized access. Without cryptographic protection, any attacker with network access can intercept and read the data, compromise its integrity, or inject malicious commands, making it unsuitable for any scenario requiring confidentiality or data integrity.
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HTTP with SSL
Why it's wrong here
HTTP with SSL, which is effectively HTTPS, provides robust encryption but is generally more verbose and resource-intensive than MQTT. The overhead associated with HTTP headers, connection management, and the full TLS handshake can consume significant bandwidth and processing power, making it less efficient and potentially prohibitive for resource-constrained IoT devices with limited battery life or network capacity.
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MQTT with TLS
Why this is correct
MQTT with TLS provides a robust and efficient solution for securing data in transit for IoT devices by encrypting the communication channel. TLS (Transport Layer Security) ensures confidentiality, data integrity, and server authentication, protecting MQTT control messages and payloads from eavesdropping and tampering. This combination leverages MQTT's lightweight publish-subscribe model with strong cryptographic security, making it ideal for constrained environments.
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CoAP with DTLS
Why it's wrong here
CoAP with DTLS is a technically valid and secure option for constrained environments, particularly for UDP-based communication, offering similar security guarantees to TLS. However, MQTT with TLS often sees broader adoption and ecosystem support for its publish-subscribe messaging paradigm, which is highly suitable for many IoT applications. While CoAP with DTLS is excellent for specific use cases requiring a RESTful model over UDP, MQTT with TLS is frequently the more common and generally applicable choice for securing IoT data in transit.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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