Comprehensive and Detailed in-Depth Explanation:
What is Homomorphic Encryption?
Homomorphic encryptionis an encryption scheme that allows computation on encrypted data without decrypting it.
The result of such computation remains encrypted and, when decrypted, matches the outcome as if operations had been performed on the plaintext.
This is particularly useful whenoutsourcing data processing to untrusted environments, like cloud service providers (CSPs).
Why the Correct Answer is C:
The primary use case of homomorphic encryption is toperform computations on encrypted data without needing to decrypt it.
This allows organizations totransmit and process confidential data on third-party systems (such as CSPs) without disclosing the data itself.
As a result, data remainssecure and privateeven while being processed on potentially untrusted or shared cloud infrastructure.
The phrase"without revealing information"aligns perfectly with the goal of homomorphic encryption, making optionCthe correct answer.
Why the Other Options Are Incorrect:
A). Processing data on a server after decrypting:
Homomorphic encryption specificallyavoids decrypting dataduring processing. This option contradicts the purpose of homomorphic encryption.
B). Maintaining confidentiality at rest and in transit:
While encryption can serve this purpose,homomorphic encryption specifically focuses on processing data while still encrypted, not just maintaining data at rest or during transmission.
D). Storing data across multiple nodes:
This option is about datastorage and access control, not aboutprocessing encrypted data. Homomorphic encryption is not related to multi-node storage security.
Extract from CompTIA SecurityX CAS-005 Study Guide:
TheCompTIA SecurityX CAS-005 Official Study Guideexplains that homomorphic encryption is used primarily when there is a need toperform calculations on encrypted data without revealing the plaintext. This is especially relevant in cloud computing environments where data privacy must be maintained despite offloading computational tasks to external servers.