01-20-2012, 02:14 PM
Use this program to remove the protection:
There are 3 types of protection of PDF files:
1. Forbid editing (copy, print, etc.) - this can be very easily bypassed using the above program.
2. Use a password to open the file - this can be bypassed by the above program, but needs too much time. Also anybody who tries to open the PDF needs the password to do so. Then, having the password he can do almost everything with the PDF.
3. Use tricks. The variety of these is not big. Generally the idea is to make the data in the PDF difficult to be edited:
- decomposing the text letters to splines, or other graphics objects, so simple copying of the text will not work anymore.
- converting the graphics to a raster image.
- splitting the raster image to many small raster images.
Generally all these can be bypassed using OCR programs like Abby FineReader that convert raster images to some other usable format.
There should be also some option to make "improper" PDF file, that can be opened properly by Acrobat. I haven't seen yet such intentionally "damaged PDFs" that open with mistake.
Another question is if you need to show somebody that a file has been edited - this is called usually "signature". It gives information if the file was kept untouched, or not.
Code:
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There are 3 types of protection of PDF files:
1. Forbid editing (copy, print, etc.) - this can be very easily bypassed using the above program.
2. Use a password to open the file - this can be bypassed by the above program, but needs too much time. Also anybody who tries to open the PDF needs the password to do so. Then, having the password he can do almost everything with the PDF.
3. Use tricks. The variety of these is not big. Generally the idea is to make the data in the PDF difficult to be edited:
- decomposing the text letters to splines, or other graphics objects, so simple copying of the text will not work anymore.
- converting the graphics to a raster image.
- splitting the raster image to many small raster images.
Generally all these can be bypassed using OCR programs like Abby FineReader that convert raster images to some other usable format.
There should be also some option to make "improper" PDF file, that can be opened properly by Acrobat. I haven't seen yet such intentionally "damaged PDFs" that open with mistake.
Another question is if you need to show somebody that a file has been edited - this is called usually "signature". It gives information if the file was kept untouched, or not.