6 ms·
Why is pixelation preferable to a big black obliterating box? To me, it seems like a lot of wasted time and effort and potential arms race between encoders and
by MattGaiser 6y ago
Why is pixelation preferable to a big black obliterating box?
To me, it seems like a lot of wasted time and effort and potential arms race between encoders and decoders and the risk of being exposed when you could just put a big black box over whatever you wish to obscure.
- rriepe 6y agoIt's not. There's never going to be a tool that does this with black bars. The only benefit I can think of is legitimacy. Having something blurred there suggests that there was actually something there.
- thotsBgone 6y agoYeah I think blurring is more aesthetic, and until recently was seemingly just as secure. It reminds me of how people have used the Photoshop swirl tool to obscure faces, but you could just use the swirl tool in the other direction to undo the effect.
- Lammy 6y ago"Mr. Swirl"! https://en.wikipedia.org/wiki/Christopher_Paul_Neil#Interpol_search_and_capture https://en.wikipedia.org/wiki/Christopher_Paul_Neil#Interpol...
- est31 6y agoBlack bars alone may still leak info. First, if you add black bars on your own and don't use professional redaction features of software, you might miss the OCR text layer of the PDF, or the bar might be added as a separate object entirely which means it can also be removed later on. Second, if you don't use monospace text, the width of the text you are redacting will reveal information about it. That's why monospace fonts are so commonly used in the intelligence community for example. Third, if you just add a black bar to a screenshot, there might be residual values of the text left in adjacent seemingly white portions of the image, but they might not be entirely white due to compression effects. Better you run it through a filter before publishing.
- davchana 6y agoYes, in pdf, add bars, & then print it again as pdf, but as image.
- jbverschoor 6y agoEven black bars all leak the face that there’s something hidden
- davchana 6y agoDo you mean the typeface/font? If it is just a word we are hiding in a sentence/paragraph; it would be like fill in a blank task for reader; much more chance to guess from context. There, the leaking length will not matter.
- davchana 6y agoOh sorry, my bad, you mean fact, not face. Yes, I agree.
- jbverschoor 6y agoah. yeah fact :-)
- antegamisou 6y ago> First, if you add black bars on your own and don't use professional redaction features of software, you might miss the OCR text layer of the PDF, or the bar might be added as a separate object entirely which means it can also be removed later on. Looking at you, Preview on macOS.
- dragonwriter 6y ago> Second, if you don't use monospace text, the width of the text you are redacting will reveal information about it. If you do use monospace text, width reveals the exact redacted character count. If you don't use monospace text, it constrains the possible contents in a more complicated way, but it leaks information either way.
- xorcist 6y agoThere is still a risk to leak the length of the password. If the font is known and the size of the rendered text can be inferred that would limit the search space considerably.
- davchana 6y agoPersonal Snippet, if I want to hide/cross something I wrote on paper, I usually change letters to something else, like u to g, i to d, nothing preplanned, whatever comes in mind, before I cross line the text in forward slashes, backword slashes, & in horizontal lines.
- bonoboTP 6y agoI thought I was the only one! Such a great trick. Just write random letters or even random sentences over your handwriting perhaps 2 or 3 times, then heavily cross it out and it's impossible to recover.
- KineticLensman 6y agoI sometimes write down on paper my banking passphrase (from which the bank makes me select letters at specific position). Afterwards I overwrite it a few times with the alphabet and a few numbers and other random letters. It's totally unreadable.
- nickjj 6y ago> There is still a risk to leak the length of the password. If the font is known and the size of the rendered text can be inferred that would limit the search space considerably. I do a lot of screencast videos and what I typically do is put a black rectangle well past the point where my secret text really ends. If my secret is: mysupersecretpassword You might end up seeing a black bar of: |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| What I'm most afraid of is accidentally having literally 1 frame of video where the bar isn't present. This is super easy to do if you're just scrolling through a timeline while editing. You need to really dive in and move frame by frame to ensure you get everything. I usually extend it a few frames in either direction just to be safe too.
- riidom 6y agoOnly reason I can think of: Pixelation has a more elegant touch than covering everything with a box (be it black, or some better suited color). Took a while to convince people to not use a bit of gaussian blur, because it's insecure. Well, ready for round 2...
- seltzered_ 6y agoWhat stops one from making a more secure pixelation algorithm? One that will shuffle around or maybe just randomly derive the pixelated blocks if they're within a certain color threshold of similarity? I still generally like pixelation over drawing a box for aesthetic purposes.
- lopmotr 6y agoFor elegance, it's a bit artificial, being tied to the technology of things that use pixels and popular software that zooms in on pixelated images as a grid of single-color squares. Maybe some unintelligible character-like symbols would look more elegant?
- xoa 6y ago>Why is pixelation preferable to a big black obliterating box? From a security perspective it has zero advantages, but I guess some people like the aesthetics? >To me, it seems like a lot of wasted time and effort and potential arms race between encoders and decoders and the risk of being exposed when you could just put a big black box over whatever you wish to obscure. There doesn't need to be an arms race, one can just erase whatever needed to be hid, put fake random text over it and then pixelate that. Ie., a prettier "black box" but still the same core method as a black box. In principle doesn't even need to be any more work, it'd be easy enough to throw together a simple "pixelate erase" script that'd take a selection, apply average solid color and random text over it, then pixelate the result all in one automatated step. The problem is if some people think any modification of the original information is ever good enough. Anything based on the original could leak information, so need to erase and then apply any desired aesthetics afterward.
- pvorb 6y agoYep, just replace the original password for "password" and pixelate that, if it really must look like a real password. And make sure to never use "password" as a real password, but that's a different level of shooting oneself in the foot.
- Hamuko 6y agoEven big black boxes require some amount of skill. https://twitter.com/Phthalaldehyde/status/1334714740740927489 https://twitter.com/Phthalaldehyde/status/133471474074092748...
- jaimex2 6y agoCan't facepalm enough. Just, amazing incompetence.
- closeparen 6y agoPeople say the same thing about scans of printouts. But I guess there is a reason for those.
- MattGaiser 6y agoThose at least destroy any non-visible data.
- pabs3 6y agoI feel like contrast enhancement or similar would be able to bring that back.
- Scoundreller 6y agoThat’s also why they scan in b&w with a potato. Also has the side-effect of making many graphs/charts impossible to interpret.
- esquivalience 6y ago> "with a potato" This is either a typo or I want to know more about it.
- chki 6y ago
- diebeforei485 6y agoThis reminds of the Markup tool[1] on iPhone. People use it to redact from screenshots, but it was (is?) actually slightly transparent by default. [1] https://9to5mac.com/2018/03/13/ios-markup-reveal-redact-sensitive-info/amp/ https://9to5mac.com/2018/03/13/ios-markup-reveal-redact-sens...
- tpoacher 6y agoone of the "underhanded c" contest winners many years ago was an entry for a redaction tool, which drew black boxes on an image in such a way that the software developer could later effectively recover the redacted information easily, while still being able to claim plausible deniability. The trick was that it worked by producing a ppm file where pixels with single digits would become zeros, but double digits would become 00, and three digit ints would become 000 (all valid values for black in ppm).
- sdenton4 6y agoReminds me of an old Perl module which translated code into a trinary alphabet with the characters space, tab, and new line. The resulting coded file is just an import statement and whitespace, but runs just fine.
- tpoacher 6y agoHere is the link if anyone's interested: http://notanumber.net/archives/54/underhanded-c-the-leaky-redaction http://notanumber.net/archives/54/underhanded-c-the-leaky-re...
- renewiltord 6y agoWait, shit I have totally done this. God damn it. Fortunately nothing super sensitive but damn.
- Lammy 6y agoNon-AMP link: https://9to5mac.com/2018/03/13/ios-markup-reveal-redact-sensitive-info/ https://9to5mac.com/2018/03/13/ios-markup-reveal-redact-sens...
- 6y ago
- ridaj 6y agoBecause pixelation doesn't attract attention as much as black box and is therefore a better placeholder. A black box with sharp edges has much more contrast than all the legit elements in the image and becomes visually dominant whereas typically you want to attract attention to something else on the page. For a similar reason, designers use "lorem ipsum" placeholder text rather than all-white or all-black placeholders when mocking up a layout
- jachee 6y agoThe clear answer is to use pixelated lorem ipsum for obfuscation. :)
- ridaj 6y agoBoom, startup idea right there. Provide secure-pixelize as a service, and monetize by selling on the side whatever info was sensitive enough for people to want to hide
- Rastonbury 6y agoWhite box then or a bunch of
- evan_ 6y agoA pixelated area communicates more clearly that there’s information present that is hidden from you- but not from others. It also can’t be mistaken for a design element.
- fermienrico 6y agoWhy always black boxes? The box could be of any color. In this case, white works best.
- huhtenberg 6y agoFor stylistic reasons. It looks less jarring when pixelated compared to being blackened out.