Re: Random access to an encrypted file

From:
"Mike Schilling" <mscottschilling@hotmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 27 Apr 2010 20:53:22 -0700
Message-ID:
<hr8bfm$8t2$1@news.eternal-september.org>
Arne Vajh?j wrote:

On 27-04-2010 04:15, Roedy Green wrote:

On Mon, 26 Apr 2010 10:41:36 -0500, Spud<fake@fkfkfkf.com> wrote,
quoted or indirectly quoted someone who said :

We've been told that we need to implement on-disk encryption of our
data files. We currently write them using RandomAccessFile and read
them using FileChannel.read(ByteBuffer).

Before I go off on my own, slog through java.security, and write a
wrapper around these routines to encrypt/decrypt, is there an easy
way to do it? Perhaps something built into the JDK that I'm missing?


The easy way would be to find a database that does encryption.
see http://mindprod.com/jgloss/sqlvendors.html
for candidates.

The awkward thing about roll your own is the growth factor that
encryption penalises you is not usually accurately predictable.


I would expect every algorithm to have a very well defined
function for the size after encryption depending on the
size before encryption. 100% predictable.


I wouldn't. E.g an algortihm whose first step is to convert an array of
chars to an array of bytes encoded in UTF-8.

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