Symmetric Cryptography and Key Algorithms BDC Practice Questions (Page 8)

Questions 36–40

1. 36expert · hard

   A developer is implementing encryption for a database that stores sensitive records. The application needs to support both exact-match queries and range queries on encrypted data. Which approach is most appropriate?

   • AUse AES-ECB for all columns
   • BUse order-preserving encryption (OPE) for range queries and a separate deterministic scheme for exact matches
   • CUse AES-CBC with a deterministic IV derived from the plaintext
   • DUse AES-GCM with a random IV for all columns
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2. 37expert · hard

   A developer is implementing a protocol that requires encrypting a small amount of data (e.g., a session token) and verifying its authenticity. The environment is a JavaScript runtime that does not have native AES-GCM support. What is the best alternative?

   • AUse 3DES-CBC with a fixed key
   • BUse AES-ECB and append a hash of the plaintext
   • CUse AES-CBC with HMAC-SHA256 (encrypt-then-MAC)
   • DUse AES-CTR without authentication
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4. 38expert · hard

   A company is deciding between symmetric and asymmetric encryption for a new API that exchanges small JSON payloads. The API runs on high-performance servers and the team is concerned about key management overhead. What is the best choice?

   • AUse asymmetric encryption for all payloads
   • BUse a hybrid scheme: symmetric encryption for payloads and asymmetric for key exchange
   • CUse no encryption because the API is internal
   • DUse symmetric encryption with a pre-shared key
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5. 39application · medium

   A company is migrating from 3DES to AES for encrypting data in transit. They are concerned about the performance impact on their servers. What is the most accurate statement regarding the performance of AES compared to 3DES?

   • AAES is slower than 3DES on all hardware platforms.
   • BAES and 3DES have similar performance because they are both block ciphers.
   • CAES is always slower than 3DES because it uses a larger block size.
   • DAES is generally faster than 3DES, especially with hardware acceleration (AES-NI).
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6. 40foundation · easy

   What is a major limitation of symmetric cryptography in a large-scale communication system?

   • AIt is too slow for encrypting large amounts of data.
   • BIt requires a unique shared key for each pair of communicating parties.
   • CIt is vulnerable to quantum attacks.
   • DIt cannot provide confidentiality for data at rest.
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