<story><title>Apple introduces end-to-end encryption for backups</title><url>https://support.apple.com/en-us/HT202303#advanced</url></story><parent_chain><item><author>fitblipper</author><text>&amp;quot;Some metadata and usage information stored in iCloud remains under standard data protection, even when Advanced Data Protection is enabled. For example, dates and times when a file or object was modified are used to sort your information, and checksums of file and photo data are used to help Apple de-duplicate and optimize your iCloud and device storage...&amp;quot;&lt;p&gt;Photo checksums can&amp;#x27;t be e2e encrypted huh? They reported today they abandoned their plans to do CSAM scanning on people&amp;#x27;s devices[1] and connecting the dots it seems like they wont need to since they can just do it in the cloud.&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.wired.com&amp;#x2F;story&amp;#x2F;apple-photo-scanning-csam-communication-safety-messages&amp;#x2F;&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.wired.com&amp;#x2F;story&amp;#x2F;apple-photo-scanning-csam-commun...&lt;/a&gt;</text></item></parent_chain><comment><author>twhb</author><text>The abandoned plan was perceptual hashing, which should return the same hash for very similar photos, while the new one is a checksum, which should return the same hash only for identical photos. I don’t think that invalidates the point, but it does seem relevant. It certainly makes it much less useful for CSAM scanning or enforcing local dictator whims, since it’s now trivial to defeat if you actually try to.</text></comment>
<story><title>Apple introduces end-to-end encryption for backups</title><url>https://support.apple.com/en-us/HT202303#advanced</url></story><parent_chain><item><author>fitblipper</author><text>&amp;quot;Some metadata and usage information stored in iCloud remains under standard data protection, even when Advanced Data Protection is enabled. For example, dates and times when a file or object was modified are used to sort your information, and checksums of file and photo data are used to help Apple de-duplicate and optimize your iCloud and device storage...&amp;quot;&lt;p&gt;Photo checksums can&amp;#x27;t be e2e encrypted huh? They reported today they abandoned their plans to do CSAM scanning on people&amp;#x27;s devices[1] and connecting the dots it seems like they wont need to since they can just do it in the cloud.&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.wired.com&amp;#x2F;story&amp;#x2F;apple-photo-scanning-csam-communication-safety-messages&amp;#x2F;&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.wired.com&amp;#x2F;story&amp;#x2F;apple-photo-scanning-csam-commun...&lt;/a&gt;</text></item></parent_chain><comment><author>mikehearn</author><text>The original implementation also involved sending a &amp;quot;safety voucher&amp;quot; with each photo uploaded to iCloud, which contained a thumbnail of the photo as well as some other metadata.&lt;p&gt;The vouchers were encrypted, and could only be decrypted if there were, I believe, 30 independent matches against their CSAM hash table in the cloud. At that point the vouchers could be decrypted and reviewed by a human as a check against false-positives.&lt;p&gt;It sounds like with a raw byte hash they might be able to match a photo against a list of CSAM hashes, but they wouldn&amp;#x27;t be able to do the human review of the photo&amp;#x27;s contents because of E2E.</text></comment>