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Re: Digital signing of printed documents

Alphonse Ogulla wrote:
Hi good people,
I wish to get your views on how I can implement a system that will
capture text of a financial document that is to be printed, run a hash
algorithm (SHA-1) over the document text, store an electronic copy of
the document and its digital signature to disk and lastly print the
document with the electronic signature at the last line of the
document. The financial document can be a ticket/receipt produced by a
POS application or an invoice/delivery note generated by an accounting
Do you think this is a reasonable way of going about this project? Is
Samba-CUPS and bash/perl scripting the best tools to use or are there
others? What is your recommendation and advise? Your comments, remarks
or criticism are welcome.

As others have mentioned, perhaps you need to tell us more about the project's purpose - what risks is it designed to protect against?

For example, the existence of the _c.txt leads me to suspect that you're worried the _b.txt files may be changed. But it's not clear why you wouldn't just store everything on the CD if that's the case?

And I'm not sure of the purpose of printing the hash on the paper ticket, since it may or may not correspond to the text that's actually printed on a specific piece of paper that's presented later. When does the printed hash get used?

Cheers, Dave

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