Problem 1 Which of the following statements about digital signature is CORRECT: A. Digital signature should be unforgeable, but can be valid by anyone who sees it. B. In digital signature, the algorithms GenerateKey, Sign, and Verify should be randomized algorithms. C. In digital signature, public key is used to encrypt a message. D. In digital signature, private key is used to decrypt a message.

Problem 1

Which of the following statements about digital signature is CORRECT:

A. Digital signature should be unforgeable, but can be valid by anyone who sees it. 

B. In digital signature, the algorithms GenerateKey, Sign, and Verify should be randomized algorithms. 

C. In digital signature, public key is used to encrypt a message. 

D. In digital signature, private key is used to decrypt a message. 

Problem 2

Which of the following statements about Goofycoin is INCORRECT:

A. A designated entity called Goofy can create new coins whenever he wants and these newly created coins belong to him.

B.  Whoever owns a coin can transfer it on to someone else.

C.  Goofycoin can address the double spending issue.

Problem 3

Which of the following statements about ScroogeCoin is INCORRECT:

A. A designated entity called Scrooge publishes an append‐only ledger containing the history of all the transactions that have happened.

B. Scrooge can build a block chain, which is a series of data blocks, each with one transaction in it.

C. ScroogeCoin can address the double spending issue.

D. ScroogeCoin can implement coin minting, transaction, and IDs' assignment in a fully decentralized way.