E-Signature Software: Sign PDF Documents with a Smart Card

BYK eSigner is a stand-alone desktop e-signature application for Windows, built to sign PDF documents with a qualified electronic certificate. Insert your smart card or USB token, enter your PIN and sign your documents in a few clicks. Documents are not sent to a server for signing; the signing takes place on your own computer.

• Smart card and USB token support (PKCS#11)
• Single or batch signing
• Timestamp and long-term validation data
• Visible signature field
• Signed PDF verification
• Windows installer package

The software finds the cards attached to the computer by itself and selects the certificate automatically. The signing steps move forward on screen in order, and the status is shown in colour throughout.

• Select the card and enter your PIN
• Prepare the certificate with "Connect"
• Select the PDF files to sign
• Choose the folder for the signed files
• Optionally add a signing reason and a visible signature
• Finish with "Start Signing"

Situations such as a wrong PIN, a blocked card, a missing card or an expired certificate are reported with clear messages instead of technical error codes. Signing with an expired certificate is not allowed.

There is no need to open and sign dozens of certificates, reports or quotations one by one. Several PDFs are selected and signed in one go. The result of each file appears in the activity log; a problematic file does not stop the job, it is skipped and failed files are listed at the end.

• Failed files reported in batch signing
• Signed files saved in a separate folder without overwriting files of the same name
• The output folder opened directly with "View Signed Files"

A timestamp is added to the signature, so the moment of signing is proven by an independent timestamp server. The server address, user details and timeout are defined in the settings screen.

During signing, validation data on the revocation status of the certificate (OCSP/CRL) is embedded in the document, so the signature remains verifiable even after the certificate expires.

The signature does not have to stay embedded in the document only; a visible signature field can also be created on the PDF page. The signature text or image is placed in the area selected on the page with the mouse. The signing reason is added to the signature details.

You can check the validity of signed PDFs you receive with the same software. Several files are verified together and the results are shown in a single colour-coded table.

• Signature integrity: whether the document was changed after signing
• Certificate chain validation against the Windows trust store
• Certificate revocation check via OCSP/CRL
• Presence of a timestamp
• A clear warning for corrupt or incomplete PDFs

In addition to the desktop application, a local signing service running on the computer is offered so that web-based applications can obtain smart card signatures through the browser. Documents prepared in internal web applications can then be signed with the user's own card.

For e-signature workflows in our laboratory software, see the KALDATA Calibration Laboratory Management Software and Testing Laboratory Software pages.

Which operating system does it run on?
It runs on Windows computers and is installed with a Windows installer package.

Are my documents sent to a server?
No. Signing takes place on your own computer; only the timestamp and revocation services are contacted.

Can I sign several documents at once?
Yes. In batch signing all PDFs are signed in one go and failed files are listed at the end.

Can I check whether a signed PDF is valid?
Yes. The signature, certificate chain, revocation status and timestamp are verified on one screen.

Can I add a visible signature?
Yes. The signature text or image is printed in the area you select on the PDF.

How can I get it?
Contact us through the quote and demo request form or by phone.