PNG iDOT chunk

Smyler [WHGhost]
6 years ago

1

The various crypt levels brought my attention to the png image format after I wrote a small script decoding it to help me solve one of the levels. So I started writing a png library in python, with the goal that it could be useful to quickly analyze a png file (my initial script really saved me some time). I already have it working, but I still have a lot to implement.
Anyway, I was doing some fuzzing with random images from the internet and I found a few images containing an iDOT chunk. This chunk should be public according to its spelling, but is not described in the png specifications (here). I did lots of research about it but only found people asking what it was meant for, and no actual answer.

Does anyone knows what this chunk is about?

If anyone is interested by the python library, it is here (The current version on github contains lots of errors which I will solve in the next commit).

14replies
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SIGKILL [r4v463]
6 years ago

0

After doing some researches, it seems that iDOT has been introduced by Apple, but without documentation, violating the rule of publicness of the iDOT chunk, because according to the naming convention, of the 2nd letter is in capital, the chunk specification must be public: https://stackoverflow.com/questions/33894790/what-is-the-idot-chunk

Sorry that I cannot help you more on this topic :x

Smyler [WHGhost]
6 years ago | edited 6 years ago

0

Thank you for the link, it’s quite helpful, maybe I will have to setup a hackintosh if want to understand how the chunk works. I really can’t stand when big companies goes against public specification, just like they were above everything.

SIGKILL [r4v463]
6 years ago

0

When they don’t go against specifications, they put their employees in the ISO committees to create the standard that will fit the company x)

Smyler [WHGhost]
6 years ago

0

As far as I know, iDOT isn’t specified in the ISO, and is not documented. Apple named it like if it was, without anyone from the ISO comity approving. I am not sure about it, but it is what most of the things I have read so far tells, and I won’t pay for the ISO document, so…

SIGKILL [r4v463]
6 years ago

0

I’ll continue to make some research. If you find anything interesting, post it here :)

x2600
6 years ago

4

Apple has a reputation for developing proprietary hardware and software. It is the main reason that I don’t buy their products.

Mugi [Mugiwara27]
6 years ago

1

karma'ed this post!

Darwin [DIDIx13]
6 years ago | edited 6 years ago

0

Hello Swift coders

Actually, my name (Darwin) is already an Apple’s OS. snif

Found this fact when I was searching a name for my OS ( DarwinOS was so cool :D )

https://en.wikipedia.org/wiki/Darwin_(operating_system)

Smyler [WHGhost]
6 years ago

0

[quote=DIDIx13]I was searching a name for my OS[/quote]
That sentence itself is cool. Are you working on homemade OS from the ground? That seems quite a lot of work…

Darwin [DIDIx13]
6 years ago | edited 6 years ago

1

Trying to* but yes I was a Windows user (And I still use it for some case don’t judge me)

And after 10 months learning how OS works how can it be done and at the same time I actually get my C# knowledge.

So, for now, the OS is on “”“"standby”“”“, the kernel isn’t finished at all yet, I was busy and I have some works to do first, sorry I have nothing to share with you, but if one day I publish it. I will share it with you guys for sure ! <3

x2600
6 years ago

0

@DIDIx13 That sounds cool. I’d be very interested in that.

dloser
6 years ago

3

Here’s another page talking about it for a different reason: https://www.landaire.net/post/apple-imageio-denial-of-service/

Best bet seems to be to examine that ImageIO handler a bit closer.

SIGKILL [r4v463]
6 years ago

0

Thanks @dloser !! @WHGhost it looks like what you were looking for ^^

Smyler [WHGhost]
6 years ago

0

Yes, it seems to be very interesting, thank you guys!

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