Choose the statement that is NOT true regarding symmetric cryptography:
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Choose the statement that is NOT true regarding symmetric cryptography:
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Answer: B. Asymmetric encryption is computationally faster and requires less CPU overhead than symmetric encryption.
This statement is factually false. Symmetric encryption (like AES) is significantly faster and has lower CPU overhead than asymmetric encryption (like RSA). Asymmetric algorithms involve complex mathematical operations on large numbers, making them computationally expensive. Statements A, C, and D are all true: symmetric cryptography requires shared keys, key distribution is indeed a major challenge, and it is widely used for bulk encryption.
Step-by-step Derivation:
Evaluate each statement:
- A) TRUE: By definition, symmetric cryptography uses a single shared secret key for both encryption and decryption.
- B) FALSE: Asymmetric encryption is orders of magnitude SLOWER and requires MORE CPU overhead than symmetric encryption. This is why hybrid systems use asymmetric encryption for key exchange and symmetric encryption for data encryption.
- C) TRUE: A well-known limitation of symmetric cryptography is the key distribution problem—securely delivering the shared key to both parties is challenging.
- D) TRUE: Symmetric encryption dominates bulk data encryption in practice due to its speed and efficiency (e.g., AES in TLS, file encryption, database encryption).
The question asks for the NOT true statement, so B is the correct answer.