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To: cs551@merlot.usc.edu
Subject: Re: About delete 
Date: Sat, 21 Apr 2007 22:45:21 -0700
From: william@bourbon.usc.edu

Someone wrote:

  > You said :
  > START QUOTE=================================
  > You should see that the following 3 lines are visible to your
  > program:
  > 
  >     FileName=...
  >     SHA1=...
  >     Nonce=...
  > 
  > So, you can extract the FileName, SHA1, and Nonce values from
  > a signed File Spec *before* to try to verify any digital
  > signatures.  Then you can use, say, the SHA1 index structure
  > to find all files with the same SHA1 files, open their
  > metadata files and find a subset that has the same Noce
  > (hopefullly, there is only one such file since you should not
  > have duplicates), then apply the corresponding certificate
  > file to verify digital signature.
  > 
  > ===================END QUOTE
  > 
  > We still have to match the filename if all the above is
  > found to be matching?

You need to find the file number in your mini-filesystem
that has exactly the same FileName, SHA1, and Nonce.
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>




  ----- Original Message -----
  From: william@bourbon.usc.edu
  Date: Tuesday, April 17, 2007 7:36 pm
  Subject: Re: About delete
  To: cs551@merlot.usc.edu
  
  > Someone wrote:
  > 
  >  > I am not clear how the delete works?
  >  > When a node gets a delete packet it verifies it with all the 
  > .pem files 
  >  > he has in his home directory and then matches the 
  > contents(file name, 
  >  > sha1, nonce) provided in the delete packet
  >  > nad then deletes the file..
  >  > is it the right flow isn't  it very inefficient or am I 
  > missing something?
  > 
  > This is inefficient.  If you look at the sample signed File Spec:
  > 
  >    http://merlot.usc.edu/cs551-s07/projects/cert/signed.txt
  > 
  > You should see that the following 3 lines are visible to your
  > program:
  > 
  >    FileName=...
  >    SHA1=...
  >    Nonce=...
  > 
  > So, you can extract the FileName, SHA1, and Nonce values from
  > a signed File Spec *before* to try to verify any digital
  > signatures.  Then you can use, say, the SHA1 index structure
  > to find all files with the same SHA1 files, open their
  > metadata files and find a subset that has the same Noce
  > (hopefullly, there is only one such file since you should not
  > have duplicates), then apply the corresponding certificate
  > file to verify digital signature.
  > --
  > Bill Cheng // bill.cheng@usc.edu 
  > <URL:http://merlot.usc.edu/william/usc/>