Visual Basic 2008 Recipes: A Problem-Solution Approach

12.15. Verify a Hash Code

Problem

You need to verify a password or confirm that a file remains unchanged by comparing two hash codes.

Solution

Convert both the old and the new hash codes to hexadecimal code strings, Base64 strings, or Byte arrays and compare them.

How It Works

You can use hash codes to determine if two pieces of data (such as passwords or files) are the same, without the need to store, or even maintain access to, the original data. To determine if data changes over time, you must generate and store the original data's hash code. Later, you can generate another hash code for the data and compare the old and new hash codes, which will show if any change has occurred. The format in which you store the original hash code will determine ...