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> Intentional false positives require knowledge of a hash. The code/network detecting this will be run on the client. So yes, a 'hash' or an equivalent will be
by chmod775 5y ago
> Intentional false positives require knowledge of a hash.
The code/network detecting this will be run on the client. So yes, a 'hash' or an equivalent will be known.
You would have to hope that the secondary system is robust enough to not fall victim to the same manipulated image. And it really is on Apple to first prove it isn't.
- jdlshore 5y agoNo, it is not. The hash is computed on the client, but hash comparison happens on the server, using some cryptographic magic that only reveals a “visual derivative” if enough images match. It’s fairly complex and I don’t recall the details, but the library of “bad” hashes is not accessible.
- tsimionescu 5y agoNo, the entire premise of NeuralHash is that no information about your pictures leaves your system unless it has been flagged as 'potentially CSAM'. NeuralHash itself is basically a DB of CSAM hashes encoded as an artificial neural network. In your example, each picture on your phone (that you are trying to upload to iCloud) would be hashed, and the hash would be sent to Apple. This is exactly the opposite of what they are promising with NeuralHash. Edit: I am almost entirely wrong, see the comment reply from krisoft. Apologies!
- krisoft 5y ago> In your example, each picture on your phone (that you are trying to upload to iCloud) would be hashed, and the hash would be sent to Apple. This is exactly the opposite of what they are promising with NeuralHash. No. You are wrong. They do hash each image and they do upload the hash derived safety voucher always. Here is the Apple technical paper: https://www.apple.com/child-safety/pdf/CSAM_Detection_Technical_Summary.pdf https://www.apple.com/child-safety/pdf/CSAM_Detection_Techni... There is a fairly complicated cryptographic algorithm which, according to apple, lets them open the safety voucher only if there is a match with the database. The user devices only have a cryptographicaly blinded version of the hash database which they can’t turn back to real hashes without apple’s private key. This means that the plain neuralhashes are not available to the end users.
- tsimionescu 5y agoThank you for the actual citation, I edited my comment to avoid misleading others!
- krisoft 5y agoThank you!
- nullc 5y ago> The code/network detecting this will be run on the client. So yes, a 'hash' or an equivalent will be known. They use cryptography to conceal the hash database from the users to guard it against accountability. Because of this, if they stuff the database with political or ethnically targeted images no one will be able to tell, you just have to trust that they haven't done that. Knowledge of a matching hash isn't a big barrier for another reason: Matching images are widely available. NCMEC reports that they had over 20 million matching images reported to them last year. It's a very reasonable assumption that some 4channer will helpfully troll the internet for likely illegal images and put up a large database of likely matches. False positives can also go the other way: Modify illegal images to match existing lawful images which are already in circulation. One could likely take legal hardcore pornography, crop it to make it impossible to identify the ages of the talent, add captions to falsely claim that they are under-age, tweak it to match targeted images, and submit it to the databases.
- simondotau 5y agoThat's all just baseless conspiracy theorising.