Title: Year 12 / Computer Science / Theory / 6 - Security, privacy and data integrity / 6.2 - Data Integrity

Q: Describe how data validation helps protect integrity of data
A: checks that data entered is acceptable

Q: Describe how data verification helps protect integrity of data
A: ensures that data entered matches original source

Q: State 6 data validation methods
A: range check, format check, length check, presence check, limit check, check digit

Q: Describe how range check helps with data validation
A: ensures data is between set of values

Q: Describe how format check helps with data validation
A: data must follow correct pattern

Q: Describe how length check helps with data validation
A: data must have exact number of characters

Q: Describe how presence check helps with data validation
A: checks if some data has been entered

Q: Describe how existence check helps with data validation
A: data entered must exist

Q: Describe how limit check helps with data validation
A: checks whether value entered is within acceptable minimum and maximum values

Q: Describe how check digit helps with data validation
A: digit is used as answer to arithmetic operation of other digits in data, if not matched, then data entered incorrectly

Q: Describe how visual check helps with data entry verification
A: person manually compares original data with entered data to check if correct

Q: Describe how double entry helps with data entry verification
A: data entered twice into computer and compared, if differences are found, goes back to raw data and fixes error

Q: Data errors may occur when data is moved in the system. Describe how you could you use a parity check for data transfer verification
A: decides to use even or odd parity before data sent, each byte has a parity bit, which is set to 0 or 1 to make parity of byte correct, after transmission, parity of each byte re-checked, if different, then error is flagged, parity blocks/byte used to identify
position of incorrect bit

Q: Describe the problem of parity checks
A: errors in an even number of bits in the same row or column could prevent error from being identified, as it could appear to be correct

Q: Data errors may occur when data is moved in the system. Describe how you could you use a checksum for data transfer verification
A: calculation carried out on data to be sent, result sent, along with data to recipient, checksum recalculated at receving end, if both sums equal, no error, otherwise, has been corrupted during transmission, request sent to re send data