Store in paper a electronic signature

In PDF format, understand that digital signature will consist of the following components, and each can be separately customized:
-Signature: A graphic that identifies the signer on the left-hand side of the appearance, such as a photo or scanned signatures. Transparent backgrounds allow a watermark to be visible in the underlying layer.
-Signature details: Signature data that the signer wants to appear to the right of the signature.
-Watermark or logo: An image that appears behind the signature. The default is the PDF logo.

@ http://learn.adobe.com/wiki/download/attachments/52658564/samplesignatures.pdf?version=1

That can be straightforward but lacking the security aspects of true signing. Cryptographic signature for non-repudiation and identify true signatory. Specifically will recommend that you check out this PDF document - focusing on pg 9 - Summary of Adobe security capabilities.

@ http://www.adobe.com/security/pdfs/acrobat_livecycle_security_wp.pdf

Adobe® LiveCycle® Digital Signatures ES2 would be an ideal solution but for user, Adobe Acrobat software can also create Adobe PDF documents, and apply
encryption, permissions, and digital signatures to Adobe PDF files. I see the online PDF useful to have quick kickstart to what you need to create a digital signature first - looks for "Adding digital signatures to PDFs" and "Validating digital signatures"

@ http://help.adobe.com/en_US/Reader/8.0/help.html

For barcode, it can be as an default image but if you are saying to input as dynamic signature image which changes each time for uniqueness of the PDF. PDF417 is a 2D Barcode not a Adobe PDF related digital signature , do not get it wrong :)
@ http://www.easesoft.net/PDF417.html

But if needed the dynamic type of barcode, it will probably need more effort and other 3rd party tools and maybe it needed form based type of PDF.
See the example of the 2D barcode PHP code that can generate the barcode, it is not digital signature though
@ http://www.tcpdf.org/examples.php

But I am thinking the below two related script may be useful - create signature and use the raw byte as barcode string to be printed. Not a PHP expertise
@ http://www.tcpdf.org/examples/example_050.phps
@ http://www.tcpdf.org/examples/example_052.phps

just some thoughts

Thanks for the information, the main question, is if I can print in the paper some hash code (For example in base64 or integrated in a codebar) to regenerate the electronic file with the signature (I think that PD417 could be use for this purpose)

Any suggestion?