@generalpotato Ish. I read the technical write up and they actually came up with a very clever privacy-focused way of scanning for child porn.
First, only photos were scanned and only if they were stored in iCloud.
Then, only cryptographic hashes of the photos were collected.
Those hashes were grepped for other cryptographic hashes of known child porn images, images which had to be in databases of multiple non-governmental organizations; so, if an image was only in the database of, say, the National Center For Missing And Exploited Children or only in the database of China’s equivalent, its cryptographic hash couldn’t be used. This requirement would make it harder for a dictator to slip in a hash to look for dissidents by making it substantially more difficult to get an image in enough databases.
Even then, an Apple employee would have to verify actual child porn was being stored in iCloud only after 20 separate images were flagged. (The odds any innocent person even makes it to this stage incorrectly was estimated to be something like one false positive a year, I think, because of all of the safeguards Apple had.)
Only after an Apple employee confirmed the existence of child porn would the iCloud account be frozen and the relevant non-government organizations alerted.
Honestly, I have a better chance of getting a handjob from Natalie Portman in the next 24 hours than an innocent person being incorrectly reported to any government authority.
From a technical perspective, how much would an image need to be changed before the hash no longer matched? I’ve heard of people including junk .txt files in repacked and zipped pirated games, movies, etc., so that they aren’t automatically flagged for removal from file sharing sites.
I am not a technical expert by any means, and I don’t even use Apple products, so this is just curiosity.
It would have worked and it would have protected privacy but most people don’t understand the difference between having a hash of known CSAM on your phone and having actual CSAM on your phone for comparison purposes and it freaked people out.
I understand the difference and I’m still uncomfortable with it, not because of the proximity to CSAM but because I don’t like the precedent of anyone scanning my encrypted messages. Give them an inch, etc.
@generalpotato Ish. I read the technical write up and they actually came up with a very clever privacy-focused way of scanning for child porn.
First, only photos were scanned and only if they were stored in iCloud.
Then, only cryptographic hashes of the photos were collected.
Those hashes were grepped for other cryptographic hashes of known child porn images, images which had to be in databases of multiple non-governmental organizations; so, if an image was only in the database of, say, the National Center For Missing And Exploited Children or only in the database of China’s equivalent, its cryptographic hash couldn’t be used. This requirement would make it harder for a dictator to slip in a hash to look for dissidents by making it substantially more difficult to get an image in enough databases.
Even then, an Apple employee would have to verify actual child porn was being stored in iCloud only after 20 separate images were flagged. (The odds any innocent person even makes it to this stage incorrectly was estimated to be something like one false positive a year, I think, because of all of the safeguards Apple had.)
Only after an Apple employee confirmed the existence of child porn would the iCloud account be frozen and the relevant non-government organizations alerted.
Honestly, I have a better chance of getting a handjob from Natalie Portman in the next 24 hours than an innocent person being incorrectly reported to any government authority.
From a technical perspective, how much would an image need to be changed before the hash no longer matched? I’ve heard of people including junk .txt files in repacked and zipped pirated games, movies, etc., so that they aren’t automatically flagged for removal from file sharing sites.
I am not a technical expert by any means, and I don’t even use Apple products, so this is just curiosity.
Great writeup! I tried searching but came up short, do you have a link to the technical documentation?
It’s on Apple’s website. Here’s the link: https://www.apple.com/child-safety/pdf/CSAM_Detection_Technical_Summary.pdf
Ty <3
It would have worked and it would have protected privacy but most people don’t understand the difference between having a hash of known CSAM on your phone and having actual CSAM on your phone for comparison purposes and it freaked people out.
I understand the difference and I’m still uncomfortable with it, not because of the proximity to CSAM but because I don’t like the precedent of anyone scanning my encrypted messages. Give them an inch, etc.