IGCSE Data Transmission Encryption and error

What is meant by the term ciphertext when used in encryption?

• an encryption or decryption algorithm

• an encrypted message

• a type of session key

• another name for plaintext

• text following an encryption algorithm

When carrying out asymmetric encryption, which of the following users would

keep the private key?

• the sender

• the receiver

• both sender and receiver

• all recipients of the message

• none of the above

In encryption, which of the following is the term used to describe the message

before it is encrypted?

• simpletext

• plaintext

• notext

• ciphertext

• firsttext

Which of the following is the correct name for a form of encryption in which

both the sender and the recipient use the same key to encrypt and decrypt?

• symmetric key encryption

• asymmetric key encryption

• public key encryption

• same key encryption

• block cipher encryption

Which of the following is the biggest disadvantage of using symmetric encryption?

• it is very complex and time consuming

• it is rarely used anymore

• the value of the key reads the same in both directions

• it only works on computers with older operating systems

• there is a security risk when transmitting the encryption key

What of the following is the final number in a code, which is calculated from all

the numbers in the code; its purpose is to find errors in data entry?

• parity check

• checksum

• cyclic redundancy check

• parity bit

• check digit

Which of the following is a form of error detection that makes use of a system

of acknowledgements and timeouts?

• automatic repeat request

• echo check

• check digit

• parity bit

• cyclic redundancy check

Which of the following methods uses an extra bit added to a byte to ensure it

contains an even number of 1s or odd number of 1s?

• cyclic redundancy check

• parity check

• checksum

• check digit

• echo check

Which of the following uses a calculated value which is sent after a block of

data; the receiving computer also calculates the value from the block of data

and compares the values?

• parity check

• check digit

• packet switching

• checksum

• automatic repeat request

Which of the following describes the check where the receiving computer

sends back a copy of the data to the sending computer to allow it to compare

the data?

• echo check

• automatic repeat request

• checksum

• parity check

• check digit