I&#x27;m also curious.  I hadn&#x27;t seen S3QL before it appeared at the top of HN.<p>Two things jump out at me from a quick glance at the site:<p>1. &quot;S3QL splits files in blocks of a configurable size (default: 10 MB)&quot; &lt;-- this is quite a large block size and will result in significantly less deduplication than tarsnap&#x27;s variable-length average 64kB blocks.  (On the other hand, large blocks significantly reduce the amount of work and RAM needed; S3QL&#x27;s tuning probably makes sense for a &quot;live&quot; filesystem.)<p>2. &quot;all data can AES encrypted with a 256 bit key&quot; &lt;-- leaving aside the grammatical problem, I can&#x27;t find anything beyond this about key management.  At best this means that anyone who can decrypt data can encrypt it, and vice versa; but the usual rule about crypto documentation applies here: If people don&#x27;t realize that the details matter, they&#x27;re probably doing something wrong.  (Unfortunately it&#x27;s 1AM and I&#x27;m allergic to snakes, or else I would dig into the code to see exactly how their crypto works.)