Cryptographic Hash Functions and Their Uses BDC Practice Questions (Page 10)

Questions 46–50

1. 46application · medium

   A software distribution system publishes SHA-256 checksums for its installer files. A user downloads an installer and verifies the checksum. Which property of the hash function ensures that the verification is meaningful?

   • APreimage resistance prevents an attacker from crafting a malicious installer that has the same checksum as the legitimate one.
   • BThe avalanche effect ensures that any change to the file produces a completely different checksum, making the verification reliable.
   • CCollision resistance prevents an attacker from finding any two files with the same hash, which is stronger than needed.
   • DSecond preimage resistance prevents an attacker from finding a different file that hashes to the same value as the legitimate installer.
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2. 47foundation · easy

   Why is salting important when storing password hashes?

   • AIt makes the hash function faster
   • BIt encrypts the password hash so that it cannot be read
   • CIt allows the password to be recovered from the hash
   • DIt ensures that identical passwords produce different hashes, preventing rainbow table attacks
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4. 48foundation · easy

   Which of the following is a common mitigation against brute-force attacks on password hashes?

   • AUsing a hash function without salt to keep hashes simple
   • BUsing a fast hash function like MD5 to reduce server load
   • CStoring passwords in plaintext to avoid hash collisions
   • DUsing a slow, memory-hard hash function like Argon2
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5. 49foundation · easy

   In a digital signature scheme, why is the message hashed before signing rather than signing the entire message?

   • AHashing encrypts the message so that only the recipient can read it
   • BHashing ensures that the signature is unique for each message
   • CHashing allows the recipient to recover the original message from the signature
   • DHashing reduces the amount of data that needs to be signed, improving efficiency
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6. 50application · medium

   In a proof-of-work blockchain, miners compete to find a nonce such that the block header hash is below a target. Which property of hash functions makes this process a valid consensus mechanism?

   • ACollision resistance: no two nonces can produce the same hash.
   • BPreimage resistance: finding a nonce that produces a hash below the target requires brute force.
   • CDeterminism: the same nonce always produces the same hash, so verification is instant.
   • DAvalanche effect: a small change in the nonce produces a completely different hash.
   Reveal Solution Discussion Select an answer first