GSEC · Question #62
Which of the following is a characteristic of hash operations?
The correct answer is D. Variable length output. NOTE - this question appears to contain an error: 'Variable length output' (D) is factually incorrect for hash functions, which always produce fixed-length output; 'Non-reversible' (B) is the standard correct answer. Explanation below reflects the provided answer key.
Question
Which of the following is a characteristic of hash operations?
Options
- AAsymmetric
- BNon-reversible
- CSymmetric
- DVariable length output
How the community answered
(30 responses)- A17% (5)
- B3% (1)
- C10% (3)
- D70% (21)
Why each option
NOTE - this question appears to contain an error: 'Variable length output' (D) is factually incorrect for hash functions, which always produce fixed-length output; 'Non-reversible' (B) is the standard correct answer. Explanation below reflects the provided answer key.
Asymmetric describes public/private key encryption algorithms such as RSA, not hash operations, which use no key at all.
Non-reversibility is in fact the most widely accepted defining characteristic of cryptographic hash functions, making this a strong candidate for the intended correct answer despite the answer key listing D.
Symmetric describes encryption algorithms that use the same key for both encryption and decryption, such as AES, which is unrelated to hashing.
The provided answer key marks D as correct. However, cryptographic hash functions by definition produce a fixed-length output regardless of input size - MD5 always produces 128 bits, SHA-256 always produces 256 bits. The actual defining characteristic of hash operations is non-reversibility (option B), and this question likely contains a keying error.
Concept tested: Cryptographic hash function defining characteristics
Source: https://csrc.nist.gov/projects/hash-functions
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