You are learning cryptography. Which of the following is correct?
A. Secret-key encryption uses a shorter key than public-key encryption to achieve a lower work factor.
B. The CBC mode of public-key encryption hides ciphertext patterns, while ECB doesn’t.
C. Block ciphers have better performance than stream ciphers on constrained hardware.
D. Stream ciphers are more vulnerable to cryptanalytic attacks than block ciphers.
Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.
My suggested answer is D. Stream ciphers are more vulnerable to cryptanalytic attacks than block ciphers.
Speed, security, and simplicity are primary concerns for designing new encryption. The simplicity in view of software implementation is often quite complex in the hardware implementation. “The hardware implementations of today’s algorithms, such as AES cipher, are inefficient for devices with limited hardware area. So, stream ciphers are used in cases that the low hardware complexity is necessitated.” (Paris Kitsos)
- Secret-key encryption can use a shorter key than public-key encryption to achieve an equal or higher work factor.
- The CBC mode of secret-key encryption hides ciphertext patterns, while ECB doesn’t. Even though it’s hypothetically possible to use CBC mode in asymmetric encryption, we don’t classify asymmetric ciphers in terms of block or stream.
- Stream ciphers have better performance than block ciphers on constrained hardware.
- Stream ciphers are more vulnerable to cryptanalytic attacks than block ciphers.
- Design of Stream Ciphers (PDF) – University of Waterloo
- On the Hardware Implementation of the MICKEY-128 Stream Cipher
- Block cipher mode of operation
- Quantum computing
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A. 密鑰(secret-key)加密使用比公鑰(public-key)加密更短的金鑰來實現較低的工作係數(work factor)。