Need help!

[ibanezfoo]

Is there a way that I can keep them from being changed from their current form?

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Print to PDF and save them to a thumb drive, burn to CD, external hard drive, etc. If you want to pay for a PDF program you can also lock them with a password (which can be cracked though, but at least you'd have a file with a date stamp and a lock so if it were altered and you needed something for court you'd have that evidence.)

[command_liner]

I have a very important question for the Calguns brain trust. Is it possible to go change email attachments after they have been sent and even forwarded? I am involved in a nondisclosure real estate law suite and it appears that someone did just that. Thank you in advance for your help.

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Email is generally not secure. PDF is not secure. Email that includes a reference to an external PDF (as opposed to an inclusion) is doubly insecure.

The visual result of rendering a PDF is specifically defined as implementation dependent. Rendering (viewing) a PDF can delete files from your disk or do any number of evil things. PDFs can have oddball, but quite traditional, analog hacks like microtext and resolution-dependent watermarks. PDF can have alternative viewing features, so the contents are totally different when viewed on different devices.

Many of the PDF rendering engines can have plugins or filters that actively change the content between the reading of the PDF data stream and the rendering of the data to the viewing context. The PDF may contain the data "10", but show the data "99". The resulting SaveAs PDF will have the value "99", not "10".

Yes, I have done this in legitimate commercial printing systems used around the world. I have several related patents and could be considered an expert witness, but am currently not certified as such by a court.

If I can do this for good, legitimate reasons, others can do similar things for less-than-honest reasons.

[welchy]

Email is generally not secure. PDF is not secure. Email that includes a reference to an external PDF (as opposed to an inclusion) is doubly insecure.



The visual result of rendering a PDF is specifically defined as implementation dependent. Rendering (viewing) a PDF can delete files from your disk or do any number of evil things. PDFs can have oddball, but quite traditional, analog hacks like microtext and resolution-dependent watermarks. PDF can have alternative viewing features, so the contents are totally different when viewed on different devices.



Many of the PDF rendering engines can have plugins or filters that actively change the content between the reading of the PDF data stream and the rendering of the data to the viewing context. The PDF may contain the data "10", but show the data "99". The resulting SaveAs PDF will have the value "99", not "10".



Yes, I have done this in legitimate commercial printing systems used around the world. I have several related patents and could be considered an expert witness, but am currently not certified as such by a court.



If I can do this for good, legitimate reasons, others can do similar things for less-than-honest reasons.

Is there a way I can retrieve the original PDF?

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[command_liner]

Is there a way I can retrieve the original PDF?

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In the general case, no there is not. If the original email transaction has a reference to something you do not have, like a cloud link or a document on a web site, there is no way to get the original content.

If there is litigation and thus discovery, you can show that things have changed, but you cannot find the original content.