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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: sci.crypt
Subject: Re: xorpng
Date: Sun, 5 Jan 2025 14:35:29 -0800
Organization: A noiseless patient Spider
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On 1/5/2025 2:18 PM, Stefan Claas wrote:
> Chris M. Thomasson wrote:
>> On 1/5/2025 2:06 PM, Chris M. Thomasson wrote:
>>> On 1/5/2025 1:25 AM, Stefan Claas wrote:
>>>> Rich wrote:
>>>>> Stefan Claas <pollux@tilde.club> wrote:
>>>>>> Rich wrote:
>>>>>>
>>>>>>> If instead you mean some kind of "special, PNG aware, encryptor that
>>>>>>> only encrypted the bitmap data of a PNG", but left the file as
>>>>>>> otherwise a proper PNG image structure, then that is slightly tricky
>>>>>>> (and an algorithm that is only useful for PNG's alone).
>>>>>>
>>>>>> Yes, this is what I mean.
>>>>>
>>>>> Which brings up the question of: why?
>>>>>
>>>>> Why go to the trouble to create an encryptor that is specalized for
>>>>> just encrypting the internal bitmap data within a PNG, leaving the rest
>>>>> as a PNG file, when a generic "byte stream" encryptor will encrypt the
>>>>> entire PNG with no extra effort?
>>>>
>>>> To make more content as allowed postable on social media, like X.
>>>>
>>>
>>> Well, posting a png to say, facebook, well... It's probablly going to
>>> turn it into a jpg... This can ruin the embedded ciphertext in the png
>>> image...
>>
>> Actually, the damn FB allows me to send my links with embedded
>> ciphertext just fine.
> 
> It is for X and not Meta.
> 

Well, sending say a PNG to X, it still might convert it into a JPG. It 
might alter things for compression purposes. This can mess around with 
your payload...