Re: Deducing key from encrypted & original data
On Tue, Dec 11, 2001 at 01:00:40AM +0100, Dries Kimpe wrote:
>
> Hi,
>
> this is something I've been wondering for some time now:
> Is it possible (or at least much easier) to extract the encryption key
> if you both have the encrypted and original data?
>
> Dries
>
> PS. I know it isn't debian-related, but it's a good question anyway...
It's called a known-plaintext attack. The answer depends on the
encryption scheme, but one of the properties of a good scheme is
that having a plaintext won't help you recover the key. In fact,
this is an essential requirement for public-key cryptography,
because the enemy can generate as much encrypted+plaintext data
as they like.
...unless you are from Hollywood - in which case a good encryption
scheme is one that can be cracked by having lots of digits flash
up on the screen, and gradually have individual digits lock into
the correct key.
Andrew
--
Andrew Bolt, Andrew.Bolt@arm.com
110 Fulbourn Road, Cambridge, CB1 9NJ, ENGLAND, +44 1223 400650
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