encrypt, not encrypt, why encrypt and how encrypt?

[Mojo]

Hi All

I know what I'm about to put down is probably more theorectical than an pure
Db prob, but I don't know where else to post!! :0)

Basically I've created a classic asp web app that connects to an sql 2008
express db via ssl and even though the whole sys runs on/through ssl I've
been told that I should encrypt certain parts of the db's content just in
case anybody gets onto my server and hacks into the db.

Now I started to use an old Base64 encryption with a key bit of code that
I've had for a bit, but somebody told me that base64 just converts the text
into a better transport method rather than actually encrypting it and its
easy to hack, but I've put a long key in and it doesn't seem to convert back
and forth properly without knowing the key - are they right?? Should I be
using something else?

Having started to encrypt certain parts, eg a person's name, dob, etc, it
suddenly dawned on me that although I'm encrypting and decrypting as I go if
I want to do search queries then it ain't gonna work. For example if I want
to find all the people with 'gar' in their name then this isn't going to
work and if I want to find all the people who are born between Apr and May
then this isn't either.

My second query is, if I've got the dbs on a dedicated server running only
one site, loads of password access only stuff and on https do I really need
to encrypt db fields as well?? If so, how do I get round these query (and
sort order) issues??

Thanks

M

[Erland Sommarskog]

Post by Mojo
Now I started to use an old Base64 encryption with a key bit of code
that I've had for a bit, but somebody told me that base64 just converts
the text into a better transport method rather than actually encrypting
it and its easy to hack, but I've put a long key in and it doesn't seem
to convert back and forth properly without knowing the key - are they
right?? Should I be using something else?

I have never dived into Base64, but I have always thought of it as
an encoding to make sure that binary data is not destroyed in transport.
Maybe there is a key, but it is not likely to be a very strong
encryption.

And if you are going to encrypt, you might as well use somthing strong
like RSA1024.

Post by Mojo
Having started to encrypt certain parts, eg a person's name, dob, etc,
it suddenly dawned on me that although I'm encrypting and decrypting as
I go if I want to do search queries then it ain't gonna work. For
example if I want to find all the people with 'gar' in their name then
this isn't going to work and if I want to find all the people who are
born between Apr and May then this isn't either.

Yes, encryption comes with quite a cost in terms of reduced flexibility.

Microsoft has a solution that circumvents the problem: Transperant Data
Encryption. With TDE, the application can access the database and
see all data as normal data. But if someone gets hold of the database
file or the backup, all the thief sees is garbage.

There is however quite a serious catch for you: TDE is only available
in Enterprise Edition, which is quite different from Express in a
budget perspective.

SQL Server also offer encryption functions so that you can encrypt a
column value - and this is avilable in Express. But then you will face
the issues you mention above.

The conclusion is that you should only encrypt data that is really
sensitive like credit card numbers. If you need to search on
encrypted columns, you can add a column with a strong one-way hash
of the value. Then you can search on the hash. Of course, that only
works if you search for the full value.