Cryptographic Hash Functions and Their Uses BDC Practice Questions (Page 11)

Questions 51–53

1. 51foundation · easy

   Which of the following is a cryptographic hash algorithm that produces a 256-bit output and is widely used in blockchain?

   • ASHA-256
   • BAES-256
   • CMD5
   • DRSA-2048
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2. 52expert · hard

   A blockchain developer is designing a sidechain that uses a two-way peg. The main chain uses SHA-256, and the sidechain uses a different hash function. The developer wants to minimize the risk of cross-chain replay attacks. Which approach best leverages hash functions to achieve this?

   • AUse a different hash function for the sidechain so that transaction hashes are different, preventing replay.
   • BRequire all transactions to be signed with a key derived from the sidechain's hash function.
   • CInclude the sidechain's genesis block hash in the main chain's coinbase transaction and require the sidechain to include the main chain's block hashes in its headers.
   • DUse the same hash function on both chains but add a different magic number to each transaction before hashing.
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3. 53foundation · easy

   Why is collision resistance important for a cryptographic hash function?

   • AIt prevents an attacker from finding two different messages that produce the same hash, which could be used to forge digital signatures
   • BIt ensures that the hash function runs quickly on all types of hardware
   • CIt guarantees that the hash output is unique for every possible input
   • DIt allows the hash function to be used for encryption
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