[tahoe-dev] proposal: add padding

[Ed Kapitein]

On Wed, 2013-07-10 at 14:06 +0000, Zooko O'Whielacronx wrote:
> On Tue, Jul 9, 2013 at 9:53 AM, Iraklis . <leontiad at gmail.com> wrote:
> > That would destroy any dedup service if different random bytes are appended. Even if the same number of random bytes are appended for equivalent encryption keys. Or i am missing sth?
> 
> Hello, Iraklis! Good to hear from you.
> 
> Let's make all pad bytes be "0" before encryption. They will be
> encrypted along with the file bytes.
> 
> Therefore, as long as the same number of padding bytes are appended
> whenever the encryption key is the same, then the dedup (convergent
> encryption) property is preserved.
> 
> Right?
> 
> Regards,
> 
> Zooko

Hi Zooko,

Be careful with zero padding, it might leave the data open for a
watermarking attack.
If (a part of) the content of a file is known, someone can gain
knowledge about the used cipher.

Just my 0.02 BTC

Kind regards,
Ed