al 
last names with surnames drawn from a largish random list. 
 
Substitution is very effective in terms of preserving the look and feel of the existing 
data. The downside is that a largish store of substitutable information must be 
maintained for each column to be substituted. For example, to sanitize surnames by 
substitution, a list of random last names must be available. Then to sanitize telephone 
numbers, a list of  phone numbers must be available. Frequently, the ability to 
generate known invalid