Top all-time · #225
Neal Krawetz
Personal blog · hackerfactor.comsecurityprogramming
Neal Krawetz writes Hacker Factor: Home Page, a personal blog at hackerfactor.com about security and programming. Since 2008, 203 different Hacker News readers have linked it 382 times, most often “One Bad Apple”. No feed was found, so read it on the site itself.
Sometimes recommended · 9 of 40 sampled comments recommend it?
Why HN links it
HN readers link Neal Krawetz's posts on photo forensics, perceptual hashing, PhotoDNA and Apple's CSAM scanning, and cite them as the source on those topics.
- Recommended for · 9 comments
- Called great, a good explanation, a good article and the best one on the topic; one reader says they learned a lot from it.
Summarised by Claude from a sample of 40 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Most-linked posts?
- One Bad Apple23 people · 33 mentions · first linked 2021-08-08
- Hacker Factor: Gender Guesser10 people · 11 mentions · first linked 2011-03-16
- Connecting the iDOTs (2020)8 people · 8 mentions · first linked 2020-09-08
- Attacked over Tor (2017)6 people · 6 mentions · first linked 2017-11-03
- Perceptual hashing of images6 people · 6 mentions · first linked 2013-05-29
- Open Source Rocks5 people · 5 mentions · first linked 2008-11-29
- Kind of Like That: Perceptual Hashing4 people · 4 mentions · first linked 2014-04-03
- Tor 0day: Snowflake4 people · 4 mentions · first linked 2021-12-22
- Tor 0day: Finding IP Addresses4 people · 4 mentions · first linked 2020-09-16
- /GenderGuesser.html4 people · 4 mentions · first linked 2009-05-14
What Hacker News says?
If you have any proof feel free to drop it. The thing that has historically made a company bound to free speech is whether or not the government requires them to specifically search for certain types of infringing content. Coincidentally, this is the current legal framework that makes reporting images of child abuse legal: companies can voluntarily choose to to either not scan for CSAM, or can choose to scan for CSA…
Comment linking /blog/index.php?/archives/955-NCMEC-2021-Reporting.html
on “Elon Musk makes $43B unsolicited bid to take Twitter private”Submitted One Bad Apple as a story · 1484 points
HN discussion> "we need to scan your phone because we need to look for this material, and by the way, we're only scanning things _we've been scanning for years already_" As far as we know, Apple is not already using their decryption keys to decrypt images upload to iCloud and compare them with known images. That's according to this blog post that claims Apple make very few reports to the NCMEC: https://www.hackerfactor.com/blog/…
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “Apple's child protection features spark concern within its own ranks: sources”Submitted Reasons Python Sucks as a story · 405 points
HN discussionSome great blogposts about exactly this: https://www.hackerfactor.com/blog/index.php?/archives/654-FC... https://www.hackerfactor.com/blog/index.php?/archives/665-Oh...
Comment linking /blog/index.php?/archives/665-Oh-FCC.html
on “Net Neutrality Day of Action: Help Preserve the Open Internet”Submitted How Perceptual Hashes Work as a story · 354 points
HN discussionIt’s catch-up in that Apple submits less than a thousand CSAM reports to NCMEC annually: > According to NCMEC, I submitted 608 reports to NCMEC in 2019, and 523 reports in 2020. In those same years, Apple submitted 205 and 265 reports (respectively). It isn't that Apple doesn't receive more picture than my service, or that they don't have more CP than I receive. Rather, it's that they don't seem to notice and theref…
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “Apple Delays Rollout of Child Safety Features”Submitted Forensic analysis of recent Victoria's Secret photo as a story · 308 points
HN discussion> Citation needed. The best one I remember is this one: https://www.hackerfactor.com/blog/index.php?/archives/929-On... > As the latest news suggests the opposite. What news?
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “Apple Photos phones home on iOS 18 and macOS 15”Submitted Tor 0day: Finding IP Addresses as a story · 257 points
HN discussion1. Previous submission ( http://www.hackerfactor.com/blog/ ) claims that PhotoDNA is reversible to 26x26 grayscale 2. What’s more important is you can reverse engineer algorithm that’s used locally to compare these hashes. Unlike with cloud-based searches other providers run, this puts significant limitations to what Apple or LEA can do on your phone. E.g. they can’t extract strings from PDF or grep through image me…
Comment linking /blog/
on “Apple’s Mistake”Submitted The Photographic Science of Detecting Fake Lottery Tickets as a story · 254 points
HN discussionThe 1-in-a-trillion claim was debunked, https://www.hackerfactor.com/blog/index.php?/archives/929-On... : > Facebook is one of the biggest social media services. Back in 2013, they were receiving 350 million pictures per day. However, Facebook hasn't released any more recent numbers, so I can only try to estimate. In 2020, FotoForensics received 931,466 pictures and submitted 523 reports to NCMEC; that's 0.056%. Dur…
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “Apple’s Mistake”Submitted Deanonymizing Tor Circuits as a story · 243 points
HN discussionThe reason they don't explain how it works is that the CSAM hash matching is an algorithm from NCMEC, which was apparently originally designed by Microsoft. If you want to learn about the algorithm/hashes, you have to, among other things, sign an NDA about it, so it's likely that Apple, legally, cannot go into detail about how it actually works. Microsoft has a page on it here if you're interested: https://www.micro…
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “Apple’s Mistake”Submitted Tor 0day: Stopping Tor Connections as a story · 227 points
HN discussion> In the current iteration they are not using AI or anything to identify "bad" content. They are matching hashes for files on on your device against known bad hashes/content. This is misleading as these are not what most technical people would think of as a hash. These are "perceptual hashes" that can compute a distance, instead of a boolean equal/different, leaving space for false-positives instead of extremely rar…
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “Apple’s Mistake”Submitted Unbelievable as a story · 226 points
HN discussionI agree that the idea of the AG bringing felony charges against Apple employees because of their approach to dealing with CSAM is pretty far-fetched. But the article you're referring to [0] is correct to point out that Apple will be silently exfiltrating unencrypted data from its users' devices to be reviewed by its employees, meaning that they'll be viewing arbitrary content from Apple users' devices without their…
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “Apple’s Mistake”Submitted Putin on the Ritz as a story · 208 points
HN discussionThese are two articles I liked that are referenced in the Python ImageHash library on PyPi, second article is a follow-up to the first. Here's paraphrased steps/result from first article for hashing an image: 1. Reduce size. The fastest way to remove high frequencies and detail is to shrink the image. In this case, shrink it to 8x8 so that there are 64 total pixels. 2. Reduce color. The tiny 8x8 picture is converted…
Comment linking /blog/index.php?/archives/529-Kind-of-Like-That.html
on “Texas is suing all of the big TV makers for spying on what you watch”Submitted Life of Brian (Krebs) as a story · 184 points
HN discussionAttacked Over Tor [2017] https://www.hackerfactor.com/blog/index.php?/archives/762-At...
Comment linking /blog/index.php?/archives/762-Attacked-Over-Tor.html
on “I use zip bombs to protect my server”Submitted Handling bot attacks against a Tor hidden service as a story · 169 points
HN discussionHere's an example of things you can do against malicious crawlers: http://www.hackerfactor.com/blog/index.php?/archives/762-Att... .
Comment linking /blog/index.php?/archives/762-Attacked-Over-Tor.html
on “A Facebook crawler was making 7M requests per day to my stupid website”Submitted The Canary Chirps as a story · 149 points
HN discussionThey don’t block CSAM because “it’s illegal” - in fact, they can’t be forced to do it without it breaking your 4th amendment rights. Instead, all CSAM reporting and blocking is done at-will by these companies, and some don’t participate (Apple[0]), so it’s a policy decision by these companies. I imagine unblocking someone due to them being exonerated by a government entity is legally risky - perhaps doing so would b…
Comment linking /blog/index.php?/archives/929-One-Bad-Apple.html
on “A dad took photos of his toddler for a doctor – Google flagged him as a criminal”Submitted PNG and Hidden Pixels as a story · 143 points
HN discussionhttps://hackerfactor.com A blog on security, privacy and (foto) forensics.
Comment linking /
on “Ask HN: What are some good technology blogs to follow?”Submitted Problems caused by Google crawlers as a story · 142 points
HN discussion
