Swordfish

Does anyone have any experience or know of any resources that would help us develop a PDF generator?

Some background: Our devices output a 'log' via various methods that gives a pass/fail report. Some customers are finding the machine operators are opening this file (which is just a .txt file) and editing it to 'hide' their mistakes.

We are thinking that if we can generate it as a PDF this will be more secure as they aren't as easy to edit. Of course someone who knows what they are doing could manage it but hopefully your average man on the street would struggle.

All the references I can find for PDF generators are PC based and the techniques they describe look very difficult to implement on a micro, mainly due to the lack of RAM.

I think you'd find a PDF generator in a PIC a real struggle to pull off.

However, we had a very similar situation to you. To combat it we put in a checksum/hash output on the end of the file. This didn't prevent them from modifying it (or help if people we're just looking at the printed output), but when imported into the program it showed that the file had been tampered with.

I've never tried it, but there's this C code https://github.com/philips/text2pdf that looks like it wouldn't be too hard to implement.

It doesn't use any encoding, so the text is in plain text format... not sure if that really fits the bill or not.

How on earth do you find this stuff Jerry??!!?

I'm good at guessing search parameters (really, it's just blind luck but that doesn't sound as good).