Exam CCSK topic 1 question 183 discussion

V10. IMPOSSIBILITY OF PROCESSING DATA IN ENCRYPTED FORM Encrypting data at rest is not difficult, but despite recent advances in homomorphic encryption (27), there is little prospect of any commercial system being able to maintain this encryption during processing. In one article, Bruce Schneier estimates that performing a web search with encrypted keywords -- a perfectly reasonable simple application of this algorithm -- would increase the amount of computing time by about a trillion (28). This means that for a long time to come, cloud customers doing anything other than storing data in the cloud must trust the cloud provider.

C. Provider must be highly trustworthy and have compensating controls to protect customer data when it is in plaintext form According to ENISA (European Union Agency for Cybersecurity), customers should expect cloud providers to be highly trustworthy and to have compensating controls in place to protect customer data when it is in plaintext form. This recognition of the cloud provider's trustworthiness and their ability to implement strong compensating controls is crucial when data processing requires temporary decryption, even though encryption is the primary security measure. This expectation helps ensure the security and privacy of the customer's data while it is being processed by the cloud provider.

D is the most logical answer. This is a two part question, and the plaintext wording is a distractor. There is no mention of Homomorphic encryption as an option in any of the study guides. CCSK Study Guide pg 126, 11.1.4.3 references HSM as a viable option.