1. White Paper – Electronic Signer
The Electronic signer
The electronic signer application offers all the neccesary features to sign
documents. To serve a broad as possible market, the Portable Document
Format (PDF) was chosen as the document format for use with the electronic
signer. Both the “classical” manual handwritten signature and digital signature
may be used to sign documents. It is also possible to add other electronic
fields in a document such as a date field, read and understood etc.
Signing with an electronic Pen
When using the electronic signer on a Tablet PC or using a specific signing
device connected to the PC, documents can be signed by hand using the
stylus. The look and feel of this signing process is identical to signing the paper
version. Drawing the signature is only allowed on predefined fields on the
document. These fields are indicated by standard PDF form fields, which can be
added by LetterGen during the document creation. When saving the document,
the signatures are embedded into the PDF document. For workflow process
reasons, signature fields not signed in a previous step remain available for
signing in a next workflow step.
On the PDF document the signature area will show as follows:
After signing, the signature will be integrated in the PDF document.
White Paper - Electronic Signer (2009-06-04) P. 1/6
BTR Services NV www.LetterGen.com

2. A sample signing workflow with the electronic Pen
(1) (2)
+ =
S/T S/T S/T S/T I I I I
Original document S/T = Signature/Text field I = inkPicture control Document to sign
S/T = Signature/Text field I = InkPicture control
Type: PDF Type: PDFSignControl
(4) (3)
S/T I I
Ouput
1 signature
Signature - S/T = Signature/Text
I = InkPicture control
field
Type: PDFSignControl
Type: PDF
(1) Create a PDF document with text fields that have an identifier that starts with
#SIG# (manual signature) or #TXT# (manual text field).
(2) Visualization of the document in the PDF SignControl. The inkPicture control floats
above the text fields in the PDF document.
(3) The user can sign or write a text in the inkPicture control.
(4) The signatures/texts will be saved in the output PDF document.
White Paper - Electronic Signer (2009-06-04) P. 2/6
BTR Services NV www.LetterGen.com

3. Digitally signing with the eID or DIGIPASS CertiID
An electronic signature is a legally recognized electronic tool, that indicates
that a person accepts the contents of an electronic message or document.
Digitally signing of documents is based on Public Key Infrastructure. By means
of PKI based smartcards, such as the Belgian eID, or a DIGIPASS CertiID from
VASCO, the electonic fingerprint of the document is being signed by a 1024 bit
RSA key resulting in a digital signature. Along with this signature a certificate
(X509) is added to the document to provide the identity of the signer. The
combination of the signature and the certifcate delivers non-repudiation proof
of the identity of the signer as well as authenticity of the signed document.
Since the signed document is fully PDF compliant both the document and the
signatures can be displayed and validated by a viewer using Acrobat Reader.
Any user that modifies and saves the document after it has been electronically
signed, will invalidate the electronic signature(s).
On the electronic signer the signing field will be shown as hereunder.
Once the signature is saved it will show in a viewer like Acrobat Reader as
follows. Also when printed, the signature will be shown in the document,
assuring the signatory's identity and document integrity.
White Paper - Electronic Signer (2009-06-04) P. 3/6
BTR Services NV www.LetterGen.com

4. A sample signing workflow using the eID or DIGIPASS CertiID
(1) (2)
+ =
S S S S P P P P
Original document S = Signature field P = Panel Document to sign
S = Signature field P = Panel
Type: PDF Type: PDFSignControl
(5) (4) (3)
P P P P
Output All signatures 1 signature image
PDF digital signature P = Panel P = Panel
Type: PDF Type: PDFSignControl Type: PDFSignControl
Check if every field is filled in All signatures in one session
(1) Create a PDF document with text fields that have an identifier that starts with
#SIG# (eID or DIGIPASS CertiID signature).
(2) Visualization of the document in the PDFSignControl. The panel control floats above
the text fields in the PDF document.
(3) The user can sign in the panel control by clicking on the control. A popup lights up
where the user can enter his PIN code. After the user has signed, an image shows
up on the panel.
(4) All signature fields are signed.
Remark: Before the signatures on the PDFSignControl will be saved in the PDF
document there will be a check if every signature field is signed. (optional)
(5) The signatures will be saved in the output PDFdocument.
White Paper - Electronic Signer (2009-06-04) P. 4/6
BTR Services NV www.LetterGen.com

5. Combination Digital Signature and handwritten text
An additional feature provided by the electronic signer are handwritten fields.
These operate in exactly the the same way as handwritten signatures. These
type of fields are available for documents on which for example the signer is
asked to explicitly write down his signature or date for example. The User has
read the document and accepts the content before signing the document. The
handwritten textfield may be used in combination with manual signatures or
digital signatures.
(1) (2) (3)
+ =
T T T T I I I I I I
S S S S P P P P P P
Original document T = Text field - S = Signature field I = InkPicture - P = Panel Document to sign Manual text
T = Text field - S = Signature field I = InkPicture - P = Panel I = InkPicture - P = Panel
Type: PDF Type: PDFSignControl Type: PDFSignControl
(7) (6) (5) (4)
I I I I
I I
P P P P P P
Output All signatures 1 signature image Manual text
PDF digital signature I = InkPicture - P = Panel I = InkPicture - P = Panel I = InkPicture - P = Panel
Type: PDF Type: PDFSignControl Type: PDFSignControl Type: PDFSignControl
- Check if every text field is filled in
Check if every field is filled in All signatures in one session
- Disable every text field
(1) Create a PDF document with text fields that have an identifier that starts with
#TXT# (manual signature).
(2) Visualization of the document in the PDFSignControl. The panel control floats above
the text fields in the PDF document.
(3) The user can write a text in the inkPicture control.
(4) The user can write a text in the next inkPicture control.
(5) The user can sign in the panel control by clicking on the control. A popup lights up
where the user can enter his PIN code. After the user has signed, an image shows
up on the panel.
(6) All signature fields are signed.
Remark: Before the signatures on the PDFSignControl will be saved in the PDF
document there will be a check if every signature field is signed. (optional)
(7) The signatures will be saved in the output PDF document.
White Paper - Electronic Signer (2009-06-04) P. 5/6
BTR Services NV www.LetterGen.com

6. Technical Requirements
The electronic signer application runs as a standalone .Net 2.0 application.
Most of the electronic signer's visible components can be configured using a
config file. Input and output of the document may be done by supplying a
filename or via transfer via stdin/stdout.
System Requirements
● Windows XP SP2 or higher
● .NET runtime 2.0
● Administrative rights
● Smart card-reader
● The Belgium Identity Card Run-time (download from
http://www.belgium.be/zip/eid_datacapture_nl.html)
White Paper - Electronic Signer (2009-06-04) P. 6/6
BTR Services NV www.LetterGen.com