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Posted by Mark Shroyer on July 19, 2007, 3:58 pm
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> Haha, Thanks for the reply. I don't think that would work to well,
> I should of explained this better. Basically what I do is send a
> proposal to a customer and I want that proposal protected. I send
> probably 50 a year to people I really don't know, and that I don't
> want them to have to do anything other than open the document.
> They should know that it is protected, but once (if) it leave
> there computer then it wont open.
>
> Make any sense?
>
> It seems like it is possible, once the document is opened it ties
> with that computers address and only opens for that computer. That
> way if he forwards it the receiver will not be able to open it.
> Seems possible to me but I really don't know too much about whats
> out there.
The problem is that you aren't really asking for traditional
encryption, you're asking for DRM. Like all software DRM systems,
this would be inherently circumventable: if the recipient can read
your data then he can ultimately copy it too, no matter how
difficult you try to make it for him. That's simply the way
computers work.
That said, Adobe Acrobat probably provides the closest to what
you're asking for in the form of its "encrypted PDFs", particularly
if you encrypt the document to the recipient's (Thawte, Verisign, or
whatever) signed x.509 key. Mind you, if the recipient is dedicated
enough then he or she will absolutely be able to send the file along
to somebody else (after decrypting it using GhostScript, etc.), but
not without a certain level of technical sophistication.
--
Mark Shroyer
http://markshroyer.com/
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Posted by Moe Trin on July 19, 2007, 4:06 pm
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On Thu, 19 Jul 2007, in the Usenet newsgroup comp.security.misc, in article
josh.dylewski@gmail.com wrote:
>Basically what I do is send a proposal to a customer and I want that
>proposal protected. I send probably 50 a year to people I really don't
>know, and that I don't want them to have to do anything other than
>open the document. They should know that it is protected, but once (if)
>it leave there computer then it wont open.
You are trying to solve a _legal_ problem with a _technical_ solution.
Ain't gonna work. Making prospective customers jump through hoops is
not the best way to get business unless you're the only game in town,
in which case they may decide to find other means of entertainment..
>It seems like it is possible, once the document is opened it ties
>with that computers address and only opens for that computer. That way
>if he forwards it the receiver will not be able to open it. Seems
>possible to me but I really don't know too much about whats out there.
Tell me - how do you think I'm replying to your article? It's really
fairly simple, and you've probably done so many times. Hint: Cut/Paste
You can send the document with what-ever technical protection you wish,
but the recipient STILL has to be able to read the d4mn thing. If the
recipient can read it, they can copy it - even if that means taking a
camera and photographing the monitor they're viewing it on. There
really is more than one way to forward the contents of a document -
even one that you've created using a non-standard font. At least I
assume you want the recipient to be able to read it... I could be
wrong of course.
Discuss your problem with your legal advisor.
Old guy
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Posted by xpyttl on July 18, 2007, 4:24 pm
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> The file that I am sending through email is .doc. I was think of
> sending PDF's though.
I'm not a Linux bigot or something like that, but I consider it pretty rude
to send a .doc file via email. MS Office files support VBA which allow a
file to do all sorts of nasty things, and email addresses are trivially
spoofed, so you are asking the recipient to take a big risk opening that
file.
If, as Todd suggests, you use PGP or something similar, you could at least
sign the file so he could be confident it came from you, but that would
require action and considerable learning on his part. The fact that you
want him to do nothing suggests that he might not be all that computer
literate, in which case it is even more inconsiderate to send him a .doc
since he doesn't even know what the risk is.
..
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Posted by on July 19, 2007, 9:49 am
If you were Registered and logged in, you could reply and use other advanced thread options >
>
> > The file that I am sending through email is .doc. I was think of
> > sending PDF's though.
>
> I'm not a Linux bigot or something like that, but I consider it pretty rude
> to send a .doc file via email. MS Office files support VBA which allow a
> file to do all sorts of nasty things, and email addresses are trivially
> spoofed, so you are asking the recipient to take a big risk opening that
> file.
>
> If, as Todd suggests, you use PGP or something similar, you could at least
> sign the file so he could be confident it came from you, but that would
> require action and considerable learning on his part. The fact that you
> want him to do nothing suggests that he might not be all that computer
> literate, in which case it is even more inconsiderate to send him a .doc
> since he doesn't even know what the risk is.
>
> ..
I know the customer and if they cant trust me then they would not make
it that far down the line of my process. I fully understand VBA and
although it warns you if a .doc has and script/macro many users shut
that off. Your point is taken, I have been leaning toward buying
acrobat and make them in there.
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Posted by Ertugrul Soeylemez on July 18, 2007, 11:48 pm
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> Send a file through email so only that person can read it. I want to
> prevent him from sending it to anyone. For his eyes only.
This is impossible. Period.
If you're afraid that the receiver might forward your message, then
there is something wrong with your relationship, and probably you
shouldn't send that message at all.
Regards,
Ertugrul S=C3=B6ylemez.
--=20
Security is the one concept, which makes things in your life stay as
they are. Otto is a man, who is afraid of changes in his life; so
naturally he does not employ security.
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