Protect PDF with user access permission, print, edit, modify, form filling permissions

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User access permissions

TABLE 3.15 User access permissions
BIT POSITION	MEANING
1-2	Reserved; must be 0.
3	(Revision 2) Print the document. (Revision 3) Print the document (possibly not at the highest quality level, depending on whether bit 12 is also set).
4	Modify the contents of the document by operations other than those controlled by bits 6, 9, and 11.
5	(Revision 2) Copy or otherwise extract text and graphics from the document, including extracting text and graphics (in support of accessibility to disabled users or for other purposes). (Revision 3) Copy or otherwise extract text and graphics from the document by operations other than that controlled by bit 10.
6	Add or modify text annotations, fill in interactive form fields, and, if bit 4 is also set, create or modify interactive form fields (including signature fields).
7-8	Reserved; must be 1.
9	(Revision 3 only) Fill in existing interactive form fields (including signature fields), even if bit 6 is clear.
10	(Revision 3 only) Extract text and graphics (in support of accessibility to disabled users or for other purposes).
11	(Revision 3 only) Assemble the document (insert, rotate, or delete pages and create bookmarks or thumbnail images), even if bit 4 is clear.
12	(Revision 3 only) Print the document to a representation from which a faithful digital copy of the PDF content could be generated. When this bit is clear (and bit 3 is set), printing is limited to a low level representation of the appearance, possibly of degraded quality. (See implementation note 16 in Appendix H.)
13-32	(Revision 3 only) Reserved; must be 1.

Q: How to set the permissions to an existing PDF file with Encrypt PDF Command Line product?
A: You can use "-k" parameter in Encrypt PDF Command Line product to set the permissions to your PDF files, for example,

encryptpdf.exe -k -828 -i C:\test.pdf -o C:\out.pdf

-828 = 0xFFFFFFFFFFFFFCC4 = 11111111 11111111 11111111 11111111 11111111 11111111 11111100 11000100

The following two command lines have same effects,
encryptpdf.exe -k -3904 -i C:\test.pdf -o C:\out.pdf
encryptpdf.exe -k 18446744073709547712 -i C:\test.pdf -o C:\out.pdf

More Examples:
[ 16 ][ 15 ][ 14 ][ 13 ][ 12 ][ 11 ][ 10][ 9 ][ 8 ][ 7][ 6][ 5][4][3][2][1] = bit positions
[ 1 ][ 1 ][ 1 ][ 1 ][ 1 ][ 1 ][ 0][ 0][ 1 ][ 1][ 0][ 0][0][0][0][0] = bits all set to zero
[32768][16384][8192][4096][2048][1024][512][256][128][64][32][16][8][4][2][1] = decimal values for each bit position

-3904 is a value to disable all options,
-3904 = 0xFFFFFFFFFFFFF0C0 = 18446744073709547712 = 11111111 11111111 11111111 11111111 11111111 11111111 11110000 11000000
-1852 is a value to enable only high quality printing,
-1852 = 0xFFFFFFFFFFFFF8C4 = 18446744073709549764 = 11111111 11111111 11111111 11111111 11111111 11111111 11111000 11000100
-3376 is a value to enable "Content Copying or Extraction and Content Extraction for Accessibility" options,
-3376 = 0xFFFFFFFFFFFFF2D0 = 18446744073709548240 = 11111111 11111111 11111111 11111111 11111111 11111111 11110010 11010000
-3872 is a value to enable "Add or modify text annotations, fill in interactive form fields",
-3872 = 0xFFFFFFFFFFFFF0E0 = 18446744073709547744 = 11111111 11111111 11111111 11111111 11111111 11111111 11110000 11100000

Helpful documentations:
Encrypting PDF files
User Access Permissions
Encrypt PDF Command Line
Encrypt PDF SDK Functions

Remark:
There are many other software have the encryption function, such as Image2PDF, PDFcamp Printer, HTML Converter, AutoCAD DWG and DXF To PDF Converter, Free Text To PDF Converter. They use the same in common algorithm RC4 or MD5 and allow to create owner password and user password to protect PDF file. For the usage, please visit www.verypdf.com.