Maybe this is where an idea comes in that I read about some time ago. It was talking about localization, specifically for number-based data such as postal/zip codes and telephone numbers. It went on to say that basically, you don't store the formatted data. You store the numbers only. No spaces, no hyphens, etc. That makes it simple to localize the data when presenting it on the user's screen, and I'm sure it makes a difference in validation as well.
djj55: Nice but may have a permission problem
Pete O'Hanlon: He has my permission to run it.
That's quite right. But in the UK plenty of organisations seem to get confused about it. Some insist that you don't include the space, and some insist you do. So I guess plenty of developers have not read the article you refer to.
In such a thing there are two levels of validation. One is for the format and the other is for the value...
Like in email...the email firstname.lastname@example.org is perfectly valid in manner of format, but hard to believe anyone will answer you from it...
The same for US zip codes, it can be easily validated for format using regex, as it or a 5 digit number or a 5 digit + hyphen + 4 digits number. However not all validly formatted zip codes are real zip codes...
If you read carefully you may came to a - fairly complicated - regex that validate not only format, but also value (I have done that for Israeli phone numbers, so it is possible as long you have some rules) - http://en.wikipedia.org/wiki/ZIP_code#Structure_and_allocation[^]
I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is. (V)
תפסיק לספר לה' כמה הצרות שלך גדולות, תספר לצרות שלך כמה ה' גדול!
Since the encryption key will be needed by both client and server, how will be able to share the key with both without exposing it to the hacker community at large? The answer is that you cannot, especially since the client will likely have the decryption key (or same key if you're using symmetric encryption) exposed and vulnerable.
"The oxen are slow, but the earth is patient."