Error Detection and Correction
- Created by: miacampbell31
- Created on: 25-03-22 12:06
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- Error Detection And Correction.
- Parity Checks
- - to ensure that a single word or byte of data has been transferred within the system correctly
- - a bit in each byte or word is reserved to be the parity bit
- - the parity bit is set to 1 or 0 depending on the data
- - if the data is corrupted, then the parity check is likely to fail
- - a specific bit in a byte is the parity bit/ 8th bit/ MSB in a byte is the parity bit.
- - the sum of the bits in a byte is odd if odd parity is being used/ even is even parity is being used
- - when a byte is received it's parity is checked
- - if the parity of the byte has changed an error has occurred/ at least 1 bit has flipped
- - when a byte is received it's parity is checked
- - the sum of the bits in a byte is odd if odd parity is being used/ even is even parity is being used
- Checksums
- - to ensure that a block of data hs been transferred within the sytem correctly
- - extra words of data are added to a block of data that are worked out from the value of the data in the block
- - at a later stage the checksum is worked out again, and compared with the original, to ensure the data has not been corrupted at some stage in the system
- - an algorithm is applied to a block/ packet of data to create a checksum.
- - the checksum is appended to the block/ becomes part of the block
- - then the block is received the checksum is recalculated using the same algorithm
- - if it differs, then an error has occurred.
- - then the block is received the checksum is recalculated using the same algorithm
- - the checksum is appended to the block/ becomes part of the block
- Cyclic Redundancy Check
- - particular type of checksum
- - commonly used to verify blocks of data stored on disks or transmitted across networks
- Echo Checking
- - feature of data transmission in which the data received is returned to the point of origin for comparison with the original data in order to check it
- - when data is received a copy is transmitted back to the sender/ course
- - where it is compared with the original
- - if it differs the original data is retransmitted
- - echo checking is an automatic process
- - if it differs the original data is retransmitted
- - where it is compared with the original
- https
- communicate protocol
- - ensures secure communication between a browser and a web server
- - authenticates the website and ensures the privacy if data while in transit
- - uses TLS or SSL
- Encryption
- - data is encoded / scrambled before transmission
- - using a key / cipher / algorithm
- - data is encoded / scrambled before transmission
- - intercepted data is meaningless / unreadable without the key
- - it is decrypted upon receipt
- Digital Certificate
- - an encrypted messaged provided by a certification authority
- - confirming that the sender is who they claim to be
- - it is attached to the message and includes a digital signature
- - which can be confirmed by sending a secure message to the certification authority
- - it is attached to the message and includes a digital signature
- - confirming that the sender is who they claim to be
- - an encrypted messaged provided by a certification authority
- Parity Checks
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