If you are a Java or .NET developer, all the following articles are useful for you.

• How to sign a PDF using iText and iTextSharp

if you just want a free Digitally sign PDF tool, try the following ones:

• PortableSigner-Tool to sign Portable Document Files (PDF)
• E-signing PDF documents with iTextSharp
• Sign PDF online, but do not know how to use it
• OpenSignPdf, project of OpenSignature , in Java, to make signed pdf
• One of my work for a RAC buyer,
  Merge XFDF to PDF Form ,Do Digital Signature then send to customer

btw,

OpenSignature is an open source project for the digital signature of documents. It works with all cards supported by OpenSC and focuses on adding support for cards from accredited Italian CAs. The goal of the project is to provide a first single product capable of supporting cards from multiple vendors/countries. This contrasts the approach taken by card vendors/providers whose software follows an exclusive single-vendor approach. OpenSignature thus attempts to make a major contribution to interoperability in the digital signature domain and aims to greatly facilitate the setup of public access points that are currently the objective of several projects in Italy. Moreover, we hope that the peer-review of the open source approach will allow us to at least match the security level of competing single-card software.

Yesterday, I got a email, he said he want a tool to sign PDF in ubuntu. At first, I decided to develope one, then I thought I have downloaded a this kind tool before, so I think just need tell him this one is ok. And if needed, I can compile it with GCJ(of course just command line), just like pdftk, do not need JVM.

I have a problem: I want to generate a pdf, then I want to apply a digital signature to it. I need a tool very similar to pdftk to do this.

More or less it has to do what you did @ http://blog.rubypdf.com/2007/02/13/merge-xfdf-to-pdf-form-do-digital-signature-then-send-to-customer/

Can you suggest / give some advice on any of the following?

* Is there anything out there already that does this, particularly that works on ubuntu?
* If not, how much difficulty is involved in implementing the ability to digitally sign a pdf into a command line application?
* Is there any documentation you would suggest as a starting point?

Any feedback would be awesome
Regards,
Daniel O’Connor

Tool to sign Portable Document Files (PDF)

PortableSigner is a signing (with X.509 certificates) program for PDF files. It’s plattform independent and runs (tested) under Windows (2000, XP, …), Linux and Mac OS X.
Features

It’s possible to sign PDF documents digital with X.509 certificates. This signed documents are read only. Therefore it’s possible to implement “electronic paper”
Sourceforge.net page and download

http://sf.net/projects/portablesigner/
What is needed?

* This program
* Java 1.5 compatible runtime
* one PKCS#12 file with your personal digital X.509 certificate (from CaCert for example)
* PDF files to sign

Operating modes

PortableSigner can work in 2 modes:

* GUI Desktop Modes : Graphical frontend to sign single documents.
* Commandline Modes : Operation from the commandline for batch or operatorless work

GUI Desktop Modes

If you have a Java 1.5 compatible runtime, unpack the ZIP file and doubleclick or invoke the following commandline from the extracted directory:

java -jar PortableSigner.jar

Now you see something like this:

The operation on base of this screen is straightforward:

1. Select your inputfile (the last used file is preselected).
2. Select an outputfile.
3. Select your PKCS#12 file (I will support other type of files and keystores later. Look in the ToDo)
4. It is possible to attach a signature block as last page of the document.
5. The password of your PKCS#12 file.
6. Press the “Sign” Button
7. Ready!

Here’s the “About …” dialog. please include the version info in every request to me!

Commandline Modes

You can use the following commandline parameter:

pfp$ java -jar PortableSigner.jar -h
usage: PortableSigner
-h Help (this page)
-n Without GUI
-o Outputfile (PDF)
-p Signaturepassword
-s Signaturefile (P12)
-t Inputfile (PDF)
pfp$

For the example above the following commandline is requiered:

pfp$ java -jar PortableSigner.jar -n \
-t /Users/pfp/Desktop/unsigned.pdf \
-o /Users/pfp/Desktop/signed.pdf \
-s /Users/pfp/Desktop/pfp.p12 \
-p MySecretPassword
Document
/Users/pfp/Desktop/signed.pdf
is generated and signed!
pfp$

The switch “-n” turns the GUI off. In all other cases the GUI is invoked to support macro mode calling!