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To: python-list@python.org
From: Mark Lawrence <breamoreboy@yahoo.co.uk>
Subject: Re: Pure Python Data Mangling or Encrypting
Date: Fri, 26 Jun 2015 22:55:11 +0100
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On 26/06/2015 22:29, Jon Ribbens wrote:
> On 2015-06-26, Johannes Bauer <dfnsonfsduifb@gmx.de> wrote:
>> On 26.06.2015 22:09, Randall Smith wrote:
>>> You've gone on a rampage about nothing.  My original description said
>>> the client was supposed to encrypt the data, but you want to assume the
>>> opposite for some unknown reason.
>>
>> While you seem to think that Steven is rampaging about nothing, he does
>> have a fair point: You consistently were vague about wheter you want to
>> have encryption, authentication or obfuscation of data. This suggests
>> that you may not be so sure yourself what it is you actually want.
>
> He hasn't been vague, you and Steven just haven't been paying
> attention.
>
>> You always play around with the 256! which would be a ridiculously high
>> security margin (1684 bits of security, woooo!). You totally ignore that
>> the system can be broken in a linear fashion.
>
> No, it can't, because the attacker does not have access to the
> ciphertext.
>
>> Nobody assumes you're a moron. But it's safe to assume that you're a
>> crypto layman, because only laymen have no clue on how difficult it is
>> to get cryptography even remotely right.
>
> Amateur crypto is indeed a bad idea. But what you're still not getting
> is that what he's doing here *isn't crypto*. He's just trying to avoid
> letting third parties write completely arbitrary data to the disk. You
> know what would be a perfectly good solution to his problem? Base 64
> encoding. That would solve the issue pretty much completely, the only
> reason it's not an ideal solution is that it of course increases the
> size of the data.
>
>> That people in 2015 actually defend inventing a substitution-cipher
>> "crypto"system sends literally shivers down my spine.
>
> Nobody is defending such a thing, you just haven't understood what
> problem is being solved here.
>

To be perfectly blunt I gave up days ago trying to follow what was being 
said, just too many words from all angles and too few diagrams for me to 
follow.  I sincerely hope it doesn't end in tears.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence