An IS auditor needs to have sufficient understanding of the various control techniques used while designing the applications. In the next few sub-sections, we will go through some of the important controls built into in an application system.
Check digits
A check digit is an extra digit used for error detection. A check digit is arrived at by a mathematical algorithm. It is added to the original data to ensure that data is not altered.
It helps to ensure that the original data is not tampered or altered. Check digits help to prevent transposition and transcription errors. The most famous example for use of a check digit is the bank account numbers assigned to customers.
For instance, a bank account number is 63000024145The last digit is the check digit, 3, and if the other numbers are correct then the check digit calculation must produce 3:
- Add the numbers placed in odd digit positions: 6+0+0+2+1+5 = 14.
- Add the numbers placed in even digit positions...
