Ch14 Internet Security Measures (diff Q tagged)

Which of the following descriptions about decryption is correct?

• Decryption decompresses a compressed file.

• Decryption converts a digital signal into an analog signal.

• Decryption converts program encoding into machine code.

• Decryption converts an unreadable piece of information into readable information using a decryption key.

Which of the following statements about symmetric key encryption is correct?

• The encryption process and the decryption process are performed at the same time.

• The key must be symmetric in a way that it spells the same forwards and backwards.

• The sender and the receiver use the same key to encrypt and decrypt a message respectively.

• The public key and the private key for an encryption are the same.

1024-bit encryption is much stronger than 128-bit encryption. However, 1024-bit encryption is not commonly used in online transactions. Which of the following are the reasons for this? (1) Most computer devices cannot handle 1024-bit data. (2) It takes much longer time for encryption and decryption. (3) The file sizes of encrypted files grow significantly.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following services can be provided by asymmetric key encryption (i.e. public and private key encryption)?

• (1) only

• (2) only

• (2) and (3) only

• (1), (2) and (3)

A message is encrypted by a public key. It is then sent to the receiver and decrypted with a private key by him. In this way, the public key and private key encryption can be used to (1) ensure that only the sender and receiver can read the data (2) verify the sender's identity (3) verify the receiver's identity

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following online activities involve data encryption?

• (1) only

• (2) only

• (2) and (3) only

• (1), (2) and (3)

A company is attacked by a hacker, who is using ransomware to demand a hefty sum of money from the company. Which of the following is the ransom tactic of the hacker?

• The hacker encrypted the company's important data, causing the company to be unable to operate normally.

• The hacker spread a virus within the company, making its employees unable to work.

• The hacker kidnapped the company's senior employees, the company had no one to sign important documents.

• The hacker destroyed the company's data, causing the company to not function properly.

Sam sent an encrypted email to May. Which of the following cryptographic keys did Sam use?

• Sam's private key

• Sam's public key

• May's private key

• May's public key

Continuing from the previous question, which of the following keys does May need to use to open an email?

• Sam's private key

• Sam's public key

• May's private key

• May's public key

In comparison to asymmetric key encryption, which of the following is a drawback of using symmetric key encryption?

• (1) If the key is compromised, the transmitted data is no longer secure.

• (2) If more than two people have the key, the recipient will not be able to confirm the identity of the sender.

• (3) Symmetric key encrypted files are large in file size.