Re: Postgresql database encryption - Mailing list pgsql-general

Vikas Sharma <shavikas@gmail.com> writes:

> Hello Guys,
>
> Could someone throw light on the postgresql instance wide or database wide
> encryption please? Is this possible in postgresql and been in use in
> production?.
>
> This is a requirement in our production implementation.
>

This sounds like a lazy management requirement specified for 'security'
purposes by people with little understanding of either technology or
security. I suspect it comes form a conversation that went along the
lines of ....

"There has been lots in the news about cyber threats"

"Yes, we need our system to be secure"

"I know, lets make one of the requirements that everything must be
encrypted, that will stop them"

"Great idea, I'll add it as requirement 14".

This is a very poor requirement because it is not adequately specified,
but more critically, because it is specifying a 'solution' rather than
articulating the requirement in a way which would allow those with the
necessary expertise to derive an appropriate solution - one which may or
may not involve encryption or hashing of data and which may or may not
be at the database level.

What you really need to do is go back to your stakeholders and ask them
a lot of questions to extract what the real requirement is. Try to find
out what risk they are trying to mitigate with encryption. Once this is
understood, then look at what the technology can do and work out the
design/implementation from there.

It is extremely unlikely you just want all the data in the database
encrypted. When you think about it, such an approach really doesn't make
sense. In basic terms, if the data is encrypted, the database engine
will need to be able to decrypt it in order to operate (consider how a
where clause needs to be able to interpret actions etc). If the db can
read the data, the keys must be in the database. If the keys are in the
database and your database is compromised, then your keys are
compromised. So provided you protect your database from compromise, you
achieve the same level of security as you do with full data encryption
EXCEPT for access to the underlying data files outside of the database
system. For this, you will tend to use some sort of file system
encryption, which is typically managed at the operating system
level. Again, for the operating system to be able to read the file
system, the OS must have access to the decryption keys, so if your OS is
compromised, then that level of protection is lost as well (well, that
is over simplified, but you get the idea). What this level of protection
does give you is data at rest protection - if someone is able to access
hour disks through some other means, they cannot read the data. This is
the same principal most people should be using with their
laptops. Protect the OS with a password and have the data on disk
encrypted. Provided nobody can login to your laptop, they cannot read
your data. Without this encryption, you can just take the disk out of
the laptop, mount it on another system and you have full access. With
disk encryption, you cannot do that. Same basic principal with the
server.

At the database level, a more typical approach is to use one way hashing
for some sensitive data (i.e. passwords) and possibly column level
encryption on a specific column (much rarer) or just well structured
security policies and user roles that restrict who has access to various
tables/columns. To implement this successfully, you need details
regarding the domain, sensitivity of various data elements and the
threats you need to protect against. If you cannot get this information
because your stakeholders don't really know what their risks are and
have not done a proper assessment and what you are really dealing with
is bureaucracy which just as a dumb "data must be encrypted" policy,
just use full disk encryption and state that all data is encrypted on
disk" and your done.

Tim 


-- 
Tim Cross