<story><title>What is Differential Privacy?</title><url>http://blog.cryptographyengineering.com/2016/06/what-is-differential-privacy.html</url></story><parent_chain></parent_chain><comment><author>ianmiers</author><text>This is something Apple really needs to release all the details of. Even if they got the crypto exactly right, they could have picked a privacy budget&amp;#x2F; security parameters that just leaks everything.&lt;p&gt;And there is every reason to be skeptical about Apple&amp;#x27;s ability to design even mildly complex crypto given iMessage&amp;#x27;s flaws. Although the break in iMessage wasn&amp;#x27;t practically exploitable, that was luck and the fact that the only way to detect  if a mulled ciphertext decrypted required attachment messages. The cryptographic mistakes were bad. Given any way to detect decryption of mulled ciphertexts for standard messages (e.g. sequence numbers, timing, actively synching messages between devices, delivery receipts from iMessage instead of APSD), Apple&amp;#x27;s crypto design bugs would have eliminated nearly all of the E2E security of iMessage.&lt;p&gt;Remember, this isn&amp;#x27;t a boon for user privacy. Apple is now collecting far more invasive data about users under the claim that they have protections in place. At best it preserves the status quo and does so only if Apple both picked the parameters correctly and implemented it correctly.&lt;p&gt;At this point Apple&amp;#x27;s position should be best summed up as: we have drastically reduced your privacy except not because magic that we (i.e. Apple) do not fully understand.</text></comment>
<story><title>What is Differential Privacy?</title><url>http://blog.cryptographyengineering.com/2016/06/what-is-differential-privacy.html</url></story><parent_chain></parent_chain><comment><author>cromwellian</author><text>Some dissenting views on the utility of differential privacy: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;medium.com&amp;#x2F;@Practical&amp;#x2F;differential-privacy-considered-harmful-f420ce717846&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;medium.com&amp;#x2F;@Practical&amp;#x2F;differential-privacy-considere...&lt;/a&gt;&lt;p&gt;Also, Apple is woefully low on details, theoretical privacy should be accompanied by openly published research papers that are peer reviewed. I understand they won&amp;#x27;t release the source, but would you trust Apple if they said they invented a new encryption algorithm, but refuse to publish an academic paper on it? I&amp;#x27;d be interested precisely in what they&amp;#x27;re doing.  Are they claiming they&amp;#x27;re doing federated learning, by gathering anonymous image data from photos, uploading it to their cloud, training DNNs on it, and then shipping the results back down to clients for local recognition? Surely they&amp;#x27;re not training on device, as this is very RAM and CPU intensive.</text></comment>