> -----Original Message-----
> From: tedd [mailto:t...@sperling.com]
> Sent: Thursday, August 12, 2010 8:32 AM
> To: Bastien Koert
> Cc: firstname.lastname@example.org
> Subject: Re: [PHP] Storing Social Security Number WAS:
> Encryption/Decryption Question
> For searching standard fields, it's a piece of cake to use %LIKE%.
> For example, let's say the investigator has a piece of paper that has
> the number "393" on it and want's to search the database for all
> phone numbers that contain "393" -- he could use %LIKE% and that
> would produce 517-393-1111, 393-123-4567, 818-122-4393 and so on.
> That's neat!
> However, if the field is encrypted, then how do you preform a partial
> search on that? You can't encrypt the search string and use that
> because you need the entire string. So, how do you solve that problem?
> If you hash the number of store the hash, then you can create a
> hashed search string and use that. But again it doesn't work for
> partial %LIKE% searches. For example, I couldn't search for "393" in
> a SS# -- I would have to search for the complete SS#.
> So, how do you solve the %LIKE% problem with encryption and hashes?
Well, if you can get all the encryption/decryption to take place in SQL,
you can use something like this pseudocode:
DECRYPT(ssn) as rawssn
HAVING rawssn LIKE '%393%';
You can assign an alias and use HAVING instead of WHERE.
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