Re: Encryption Solution

[Tom Ritter <tom () ritter vg>]

As far as the "flipping one bit doesn't trash the whole archive" part
- you may want to read up on Cipher Modes and Error Propagation[1]
Flipping one bit will always mess up the block that that bit is in.
Just the way encryption works - and why it's usually paired with other
integrity checks and error correcting.  Depending on the Cipher Mode,
that block may mess up many other blocks, or not.  And it also relies
on the program you're using being able to recover from this.

You may be able to get around this by using a stream cipher - I
actually can't recall any literature I've seen on using stream ciphers
to get around the error propagation issues with block ciphers now that
I think about it... so if anyone knows anything about that, please
reply to me or the list.

Anyway, two popular programs are gpg (which I've never used on a large
archive) and Truecrypt (which can make very large archives).  I am
unsure about how they recover from errors.  I think your best bet in
that area will be verified backups using a hash function.


-tom
[1] http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Integrity_protection_and_error_propagation

On Wed, Jan 21, 2009 at 7:47 AM, Sebastian Anding <kb () cccmz de> wrote:
> Dear Listreaders,
>
> we are searching for an encryption solution that can handle an amount of 25 GB.
> The encrypted archive should be save, so that one flipping bit don't make trash
> of the whole archive.
>
> Are there any solutions known to you?
>
> Sebastian A.