Ron Green wrote:

> When I said it couldn't be used for identity I meant if you can't
> guarantee uniqueness.How would you know if you retrieved the correct
> data.

You don't need uniqueness. The hash did its job when you can almost 
instantly chop billions of strings down to a short list of candidate 
strings. After the hash collision, you trivially search the list for the 
actual target. The point is to access the stored value, at the target 
location, quickly!

This is how Google works, for example...

-- 
  Phlip