Click “Encrypt” now in Adobe Acrobat. Make sure that “Protect for Web Pages” is checked. Click “Next.” Click “I understand this operation” to confirm the operation. Click “Save Changes.” Click to Enable If that doesn't work you can try to enter the following password and set the “Protect for Web Pages” to “No Permission!” Encryption: Advanced encryption is a feature in most Microsoft and Linux software, to prevent users from modifying PDF files or removing encrypted files, these applications use different methods. Some programs have an “Advanced Encryption” option that, when enabled, prevents software from being able to copy, open and change files in any location. The Advanced Envelopment option is not available on Internet Explorer, and not on some operating systems for example, Windows XP. On a Mac, you can download and run a free utility called kit to circumvent that restriction. You can use this online password setting with these products: Adobe Acrobat Reader, Adobe Acrobat Reader X, Adobe Acrobat Reader Professional (and EDP) Reader, and Adobe Digital Editions Reader. It can also be configured for an unlimited number of files. Encryption: The free software package and service: is for non-commercial file copying. It can also make encrypted PDF copies. This product is not available for commercial use, however. Adobe's Encrypted e-book service is available to Microsoft customers. If you need a way to create e-book files that cannot be copied, or even that are unreadable with an average digital camera, e-book reader or e-book reader, try this service. The service works best with Adobe's proprietary e-book format that is called Open Digital Book Format (Ode). Adobe recommends using the latest open versions. The program is free, though there is no time limit on how often files you want to create are protected. For more information, see . Other products are: Digital Book Designer (DID) (Windows only), Create PDF (Windows only), EPUB2 (Windows, Mac for Mac users only) or Caliber.