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Hi Paul
Thank you very much for your feedback which is very informative.
I understand that concerning the encryption of credit card numbers, it is imperative to respect the PCI
DSS document. I am going to study it. However, I would like to say that I chose my example badly by using a table storing credit card numbers.
In fact, my problem is more generic.
I want to implement a solution that encrypts “sensitive” data and can retrieve data with good performance (by using an
index). I find that the solution you propose is very interesting and I am going to test it. Best Regards Didier ROS De : paul@xxxxxxxxxxxxxxx [mailto:paul@xxxxxxxxxxxxxxx]
Hi Didier, I’m sorry to tell you that you are probably doing something (ie handling/storing credit cards) which would mean you have to comply with PCI DSS requirements. As such you should probably have a QSA (auditor) who you can run any proposed solution by (so you know they will be comfortable with it when they do their audit). I think your current solution would be frowned upon because: - cards are effectively stored in plaintext in the index. - your encryption/decryption is being done in database, rather than by something with that as its sole role. People have already mentioned the former so I won’t go into it further But for the second part if someone can do a
then you are one sql injection away from having your card data stolen. You do have encryption, but in practice everything is available unencrypted so in practice the encryption is more of a tick in a box than an actual defence against bad
things happening. In a properly segmented system even your DBA should not be able to access decrypted card data. You probably should look into doing something like: - store the first 6 and last 4 digits of the card unencrypted. - store the remaining card digits encrypted - have the encryption/decryption done by a seperate service called by your application code outside the db. You haven’t gone into what your requirements re search are (or I missed them) but while the above won’t give you a fast exact cc lookup in practice being able to search using the first 6 and last 4 can get you a small enough subset than
can then be filtered after decrypting the middle. We are straying a little off PostgreSQL topic here but if you and/or your management aren’t already looking at PCI DSS compliance I’d strongly recommend you do so. It can seem like a pain but it is much better to take that pain up front
rather than having to reengineer everything later. There are important security aspects it helps make sure you cover but maybe some business aspects (ie possible partners who won’t be able to deal with you without your compliance sign off documentation). The alternative, if storing cc data isn’t a core requirement, is to not store the credit card data at all. That is generally the best solution if it meets your needs, ie if you just want to accept payments then use a third party who is
PCI compliant to handle the cc part. I hope that helps a little. Paul Sent from my iPhone
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