Re: Doubled-up security??

From: bowgus (bowgus_at_rogers.com)
Date: 01/05/05 

Date: Tue, 4 Jan 2005 22:32:31 -0500

If a key length were say 56 bits, and an algorithm was applied say 3 times,
then effective key length would be 168 bits.

<nemo outis@erewhon.com (nemo outis)> wrote in message
news:CGHCd.699611$nl.49910@pd7tw3no...
> In article <MPG.1c44c0f2ae48170d989739@news.eclipse.co.uk>,
> Livewire <livewire_100@N.O.S.P.A.M.hotmail.com> wrote:
> >
> >
> >I've got 3 different encryption programs on my computer.
> >
> >If I encrypt a file using one program
> >
> >then encrypt the encrypted file again using another program
> >
> >then encrypt it again using a third program
> >
> >
> >will it make it three time harder for someone to hack into?
> >
> >
>
>
> Assuming there are no cross dependencies in the algorithms (and
> that the passwords are sufficiently strong and independent) then
> sequentially encrypting something with two algorithms of
> equivalent strength does indeed make it twice as difficult for
> the adversary to decrypt.
>
> However, lest you become too excited about this, note that by
> doubling the difficulty you have only added one bit to the
> "effective" encryption. That is, if each algorithm was 256-bit
> then their use together is equivalent to 257 bits.
>
> Not so impressive when put that way, eh?
>
> RTegards,
>

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