How does Col-E protect against frequently repeating values?
When encrypting data in columns, if a column contains the same value repetitively, that same value will typically be encrypted to the same encrypted value. While someone may not be able to discern what that encrypted value is, they will be able to determine all the records that have that same value. For columns that contain such repeating values, such as salaries (“Who makes the same as me?”), PIN’s (“Who has the same PIN? I just have to figure out one and I know the rest”), etc. that can be a risk. Col-E has a feature to protect against this risk called Repeating Values Protection (RVP). RVP ensures that each value in a column encrypts to a different encrypted value, thus obscuring the identical values.