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+This script allows to protect the PDF, that is to say prevent people from copying its content, print it or modify it.
+
+SetProtection([array permissions [, string user_pass [, string owner_pass]]])
+
+permissions: the set of permissions. Empty by default (only viewing is allowed).
+user_pass: user password. Empty by default.
+owner_pass: owner password. If not specified, a random value is used.
+
+The permission array is composed of values taken from the following ones:
+
+    * copy: copy text and images to the clipboard
+    * print: print the document
+    * modify: modify it (except for annotations and forms)
+    * annot-forms: add annotations and forms 
+
+Remark: the protection against modification is for people who have the full Acrobat product.
+
+If you don't set any password, the document will open as usual.
+If you set a user password, the PDF viewer will ask for it before displaying the document.
+The master password, if different from the user one, can be used to get full access.
+
+Note: protecting a document requires to encrypt it, which increases the processing time a lot.
+This can cause a PHP time-out in some cases, especially if the document contains images or fonts.
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