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<div class="moz-cite-prefix">Sorry when i said similar i meant
equivalent i didn't assume content based hashing with a similarity
threshold, etc...<br>
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Regards,<br>
<br>
Iraklis<br>
On 07/12/2013 05:57 PM, Tony Arcieri wrote:<br>
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cite="mid:CAHOTMVLFbE=jA1=wkgzHb8icFJhOe9P1aE7n7X2ZQ9jn9-QH=A@mail.gmail.com"
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<div dir="ltr">On Fri, Jul 12, 2013 at 2:37 AM, Iraklis . <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:leontiad@gmail.com" target="_blank"
onclick="window.open('https://mail.google.com/mail/?view=cm&tf=1&to=leontiad@gmail.com&cc=&bcc=&su=&body=','_blank');return
false;">leontiad@gmail.com</a>></span> wrote:<br>
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.8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>You are missing the following:<br>
Files are encrypted for deduplication. That implies a
way to derive a key from the content of the files.
That is if two files are similar they will have
similar ciphertexts</div>
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<div>No, because they are encrypted under a key derived by a
hash function, and one property of a secure hash function
is that similar content produces completely different
hashes, even if you just change one bit.</div>
<div><br>
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<div>Using this content hash to seed a PRNG (and derive
encryption keys for the content) will produce completely
different pseudorandom padding, even for similar files.</div>
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-- <br>
Tony Arcieri<br>
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