On Thu, 28 Aug 2014 12:54:33 +0200, "Svein Erling Tysvær
svein.erling.tysvaer@... [firebird-support]"
<firebird-support@yahoogroups.com> wrote:

> At my workplace, we encrypt (or obfuscate) some fields in our programs

and

> only use Firebird for storage of the field (hence, Firebird knows

nothing

> about the encryption). One drawback with encryption is that it limits

use

> of indexes - it may be possible to use an index for exact match, but not
> for other things like BETWEEN, >=, LIKE or STARTING. Hence, think twice
> before encrypting fields in huge databases.

Depending on the encryption algorithm, indexes might be entirely unusable.
With a CBC algorithm and a random IV - which is the right choice -
encrypting the same cleartext leads to different ciphertext.

Mark