Cryptographic Hash Functions and Their Uses BDC Practice Questions (Page 9)

Questions 41–45

1. 41foundation · easy

   You download a file and its SHA-256 hash from a trusted website. After downloading, you compute the file's hash and it matches. What can you conclude?

   • AThe file is compressed
   • BThe file is free from malware
   • CThe file is encrypted
   • DThe file has not been altered during download
   Reveal Solution Discussion Select an answer first
2. 42foundation · easy

   What role do hash functions play in proof-of-work mining?

   • AHash functions are used to compress the block data to save space
   • BMiners use hash functions to encrypt transactions before adding them to a block
   • CMiners repeatedly hash block data with a nonce until the hash meets a difficulty target
   • DHash functions are used to generate the private keys of miners
   Reveal Solution Discussion Select an answer first
4. 43foundation · easy

   Which of the following best describes a cryptographic hash function?

   • AA function that maps data of arbitrary size to a fixed-size output, with properties such as preimage resistance and collision resistance
   • BA function that encrypts data so that it can be decrypted with the correct key
   • CA function that generates a random number from a seed value
   • DA function that compresses data to a smaller size while allowing the original data to be reconstructed
   Reveal Solution Discussion Select an answer first
5. 44application · medium

   A security team is analyzing a data breach where an attacker obtained a database of password hashes. The hashes were generated with a fast, unsalted algorithm. The team observes that many users have the same hash. Which attack is most likely to be successful against this database?

   • AA collision attack to create a different password that hashes to the same value.
   • BA dictionary or rainbow-table attack, because identical hashes reveal identical passwords and unsalted hashes allow precomputation.
   • CA length-extension attack to modify the hashes and bypass authentication.
   • DA preimage attack to recover the original passwords from the hashes.
   Reveal Solution Discussion Select an answer first
6. 45application · medium

   A security engineer is evaluating the risk of a birthday attack on a hash function used for digital signatures. The organization signs documents, and an attacker wants to create a fraudulent document that hashes to the same value as a legitimate one. Which property of the hash function is directly challenged by this attack?

   • ACollision resistance
   • BSecond preimage resistance
   • CDeterminism
   • DPreimage resistance
   Reveal Solution Discussion Select an answer first