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Apple was talking about the chance of accidental false positives. There is a 1 in 4 billion chance that if I send a message to an IP address, it will be yours.

Apple was talking about the chance of accidental false positives. There is a 1 in 4 billion chance that if I send a message to an IP address, it will be yours. The fact that I can know your IP address and send you a message intentionally does not make the previous statement false. > As Apple's hash algorithm is entirely broken and useless, a malicious actor can easily craft a NSFW, but otherwise legal image, that has a hash matching one in the CSAM database, that is visually ambiguous in that context (for example, a close-up). Targeted attacks could be launched on unsuspecting victims as simply as sending them an image. Everybody keeps talking about this scenario as if it is any different whatsoever from sending people actual regular old-fashioned CSAM, which A: already happens, B: requires less effort on the part of the attacker, and C: isn't reliant on the recipient uploading them to iCloud, triggering several layers of filtering and detection, which may or may not result in law enforcement interest depending on your forgery's ability to fool professional investigators at NCMEC who are comparing it alongside the original. The attack you're describing is less effective and more difficult than existing ones.

argvargc 5y ago
No, the attacker is committing a crime with the attack you describe, but has plausible deniability that they are not with the Apple-nonsense enabled attack vector. This is a huge difference as not only does Apple facilitate a gain-of-function in terms of potential detriment to the victim of an attack, the newly-enabled vector also indemnifies the attacker. The effort required to come up with a hash collision in SHA256 is something on the order of the power output of a trillion suns for a billion years (or some other meaninglessly-prohibitively-large amount). Despite such metrics and off-the-shelf solutions being readily attainable within this field Apple has implemented a system that has resulted in a collision within days, followed by a free automated collision generation tool. This demonstrates absolute gross incompetence in design, and permanently eliminates any trust any sensible individual can ever have in the system despite your protestations. There is simply nothing you can say to convince any sane person otherwise, the situation has been factually described and it is what it is.

argvargc 5y ago

No, the attacker is committing a crime with the attack you describe, but has plausible deniability that they are not with the Apple-nonsense enabled attack vector. This is a huge difference as not only does Apple facilitate a gain-of-function in terms of potential detriment to the victim of an attack, the newly-enabled vector also indemnifies the attacker. The effort required to come up with a hash collision in SHA256 is something on the order of the power output of a trillion suns for a billion years (or some other meaninglessly-prohibitively-large amount). Despite such metrics and off-the-shelf solutions being readily attainable within this field Apple has implemented a system that has resulted in a collision within days, followed by a free automated collision generation tool. This demonstrates absolute gross incompetence in design, and permanently eliminates any trust any sensible individual can ever have in the system despite your protestations. There is simply nothing you can say to convince any sane person otherwise, the situation has been factually described and it is what it is.