From: paul@poboy.b17c.ingr.com (Paul Robichaux)
Date: Mon, 9 Jan 95 07:45:17 PST
To: dfloyd@io.com
Subject: Re: Data Haven problems
In-Reply-To: <199501071710.LAA21334@pentagon.io.com>
Message-ID: <199501091546.AA19741@poboy.b17c.ingr.com>
MIME-Version: 1.0
Content-Type: text/plain


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> Any ideas on how to guard against mailbombs, and to confirm to the sender
> that their files are stored successfully?  Perhaps do a mailing with
> a test command that validates the existance of the file, and sends a
> reply back wether the file is okay or not, or would this result in a
> possible security hole?

To solve problem #1, use digital postage of some form. Digicash, FV,
Tacky Tokens, Mountain Dew futures... just require a per-storage-unit
charge _to initially check in the file_. You can of course charge for
storage over time, too.

To solve problem #2, send an MD5 hash of the file back to the sender.
Ideally, you would also provide (in perl, C source, csh, or whatever)
a submission script which outputs an MD5 hash before the file is sent.
As long as the before-sending hash matches the hash returned by the
haven, you can assume that the file is intact.

> Lastly, instead of postage (like a remailer would get), how hard would it
> be to implement "rent" where if the "rent" is not paid, and a grace period
> has elapsed the file would be trashed.  All this while preserving the
> anonymity of the sender and the data haven site.

Not very. Use a dbm database to map "rent due" dates by file, then
periodically sweep through the database.

> As to the code, this will have to be my second rewrite as I am going to
> do it in perl code, rather than C...  last rewrite was from a daemon to
> a program activated by a .forward file.

Perl has the nice property of being fairly portable, too.

- -Paul

- -- 
Paul Robichaux, KD4JZG       | Good software engineering doesn't reduce the 
perobich@ingr.com            | amount of work you put into a product; it just 
Not speaking for Intergraph. | redistributes it differently.
		  ### http://www.intergraph.com ###

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