While light-weight pdf readers are a very good alternative to "Adobe Reader" and there are more reasons other than just the bloat to use them, but there are times when a user needs to rely upon the official PDF reader from Adobe. Today we will see how to use free utility software "Adobe Reader X" to digitally sign a document, a digital signature or e-signature is a mathematical encryption technique used to ensure authenticity of a digital message or document. A valid digital signature gives a recipient reason to believe that the message was created by a known sender, and that it was not altered or tampered with in-transit.

If you are using any alternative PDF viewers like Google Docs Viewer or Sumatra Reader to get away from Adobe Reader bloat - you might land on an error as shown below when trying to read some PDF files.

Adobe Acrobat Reader has not been my choice of free PDF reader utility thanks to it's security issues, bloat and intrusive updater. Adobe has now started to address these issues and the latest release of "Adobe Acrobat Reader X" features new security measure known as “Adobe Reader Protected Mode” which is a sandboxing functionality which basically isolates the PDF reader from rest of the system shielding the user computer from any threat embedded into the document, the technology is based on Microsoft’s “Practical Windows Sandboxing”.