Chapter 2 - Data Transmission (IGCSE Computer Science)

A message sent to the receiver indicating that data has been received correctly (used in the ARQ error detection method)

• timeout

• ISBN 13

• Modulo-11

• Acknowledgement

A type of encryption that uses public keys and private keys to ensure data is secure

• Symmetric

• Asymmetric

• Blowfish

• Advanced Encryption Standard

A method of checking transmitted data for errors; it makes use of acknowledgement and timeout to automatically request re-sending of data if the time interval before positive acknowledgement is too long

• Checksum

• Check Digit

• Automatic repeat request (ARQ)

• Echo Check

An additional digit appended to a number to check if the entered number is error-free; a data entry check and not a data transmission check

• Check Digit

• Parity Check

• Echo Check

• Checksum

A verification method used to check if data transferred has been altered or corrupted; calculated from the block of data being sent

• Echo Check

• Checksum

• Parity Check

• ARQ

Encrypted data that is the result of putting a plaintext message through an encryption algorithm

• encryption key

• decryption key

• ciphertext

• eavesdropper

An error checking method in which all the 1-bits in the data packet payload are added and the total is stored in the packet trailer; the same calculation is repeated at the receiving station

• Cyclic redundancy check (CRC)

• Automatic repeat request (ARQ)

• Echo check

• Checksum

A small part of a message/data that is transmitted over a network; after transmission all the data packets are reassembled to form the original message/data

• packet header

• packet trailer

• payload

• data packet

Another name for a hacker who intercepts data being transmitted on a wired or wireless network

• wiretapper

• earwigger

• eavesdropper

• snooper

A method used to check if data has been transferred correctly; data is sent to a receiver and then immediately sent back to the sender; the sender then checks if the received data matches the sent data

• checksum

• parity check

• check digit

• echo check