Error detection and Encryption Flashcards
What is a Checksum?
A process that adds a check digit at the end based on an algorithm using the data to check it matches with the original.
Needs more processing for the algorithms, and doesn’t self-repair or check for errors.
Give a disadvantage of a Checksum.
Needs more processing for the algorithms.
Doesn’t self-repair or check for errors.
What is the Parity System?
A single bit added to a transmission that can be used to check for errors in the transmitted data.
How does the Parity System work?
Once the data is received a parity check is carried out.
If there is an even number of bits that are 1, the even parity is 0 and the odd parity is 1
If there is an odd number of bits that are 1, the even parity is 1 and the odd parity is 0
The choice is based on whether the system is even or odd.
Simple to implement
Requests a transmission if an error occurs.
However, will not detect if 2 errors occur
Give advantages and disadvantages of the parity system.
Simple to implement.
Requests a transmission if an error occurs.
However, will not detect if 2 errors occur.
What is the Majority Voting system?
A system that sends the same bit multiple times, going with the most common bit value, deciding the majority bit.
Give advantages and disadvantages of the Majority Voting system.
Self-repairs, allowing the errors to be located.
Will fail if enough errors occur to switch the majority vote (3+ errors).
Sends 5x as much data.
What is Symmetric Encryption?
The same key is used for encryption and decryption.
What is Asymmetric Encryption?
Different keys are used for encryption and decryption.
What is the Vernam Cipher?
A randomly generated one-time binary key, which is the same length as the plaintext.
This is XOR’ed with the plaintext to produce ciphertext. Symmetric encryption.
Advantages of the Vernam Cipher?
It is very secure, but extremely long.
Impossible to crack without a key, only allowing guessing.
What is meant by the term ‘Perfect Security’?
Encryption that is impossible to crack in a reasonable amount of time.
What is Encryption?
The process of using an algorithm to change data to only be read by the intended recipients.
What is Decryption?
The process of turning the encrypted data back into data that can be understood.
What is a Cipher?
The algorithm which is used to encrypt or decrypt data.
