Return-Path: william@bourbon.usc.edu Delivery-Date: Sun Nov 16 20:28:56 2008 X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on merlot.usc.edu X-Spam-Level: X-Spam-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.2.3 Received: from bourbon.usc.edu (bourbon.usc.edu [128.125.9.75]) by merlot.usc.edu (8.14.1/8.14.1) with ESMTP id mAH4SuWf029540 for ; Sun, 16 Nov 2008 20:28:56 -0800 Received: from bourbon.usc.edu (localhost.localdomain [127.0.0.1]) by bourbon.usc.edu (8.14.2/8.14.1) with ESMTP id mAH4PI5g017107 for ; Sun, 16 Nov 2008 20:25:18 -0800 Message-Id: <200811170425.mAH4PI5g017107@bourbon.usc.edu> To: cs551@merlot.usc.edu Subject: Re: Confusion with nonce Date: Sun, 16 Nov 2008 20:25:18 -0800 From: Bill Cheng Someone wrote: > What if a user tries to store the same file (identical sha1 and filename) > multiple times with a store command? Would they be allowed to do that > because the newly stored file will have a different nonce than the existing > copy(since the nonce is not data dependent)? Yes. They must be allowed to do that. Since the nonce will be new, it's considered a different file. Also, the 2nd time the file is store, the user may enter different set of keywords. > It seems like nonces are only > used for probablisitic forwarding and deleting. A nonce is used to distinguish different versions of the same file having the same FileName and SHA1. -- Bill Cheng // bill.cheng@usc.edu -----Original Message----- From: Bill Cheng [mailto:william@bourbon.usc.edu] Sent: Sunday, November 16, 2008 7:03 PM To: cs551@merlot.usc.edu Subject: Re: Confusion with nonce Someone wrote; > The spec defines nonce as: > A nonce can be used to distinguish different versions of the same file. > (If a file with a certain SHA1 value is created by a user and, at a > later time, the same file with the same SHA1 value is created by the > same user or another user, these 2 files will have different nonces.) > *Therefore, we consider that file Y is a copy of file X if X and Y have > identical FileName, SHA1, and Nonce (everything else about X and Y are > assumed to be identical).* > > I am not very clear about the line in bold. Does it mean that if a node > sees a file with the same filename, sha1 and nonce as another file that > is stored in the node, it has to discard that file? Right ? Correct! -- Bill Cheng // bill.cheng@usc.edu