The Power of E-Signature in JavaScript


Digital signatures have transformed the way we validate documents, replacing the traditional ink-on-paper signatures with electronic equivalents. In addition to the convenience, e-signatures offer several advantages over their physical counterparts. By creating a unique signing fingerprint, e-signatures secure and protect digital documents. Moreover, they provide authentication, integrity, and non-repudiation, ensuring that the signer cannot deny their involvement. This article explores the benefits and inner workings of e-signatures in JavaScript.

Advantages of E-Signatures


One of the primary advantages of e-signatures is precise identification. With a valid e-signature, you can confidently determine the document’s creator. This level of authentication is invaluable when it comes to establishing trust and accountability.


E-signatures allow users to easily verify whether the contents of a document have been tampered with after signing. By comparing the unique values generated from the document data and private key, integrity can be ensured. If these values match, the data remains unaltered, and the e-signature is valid.


With non-repudiation, e-signatures make it impossible for the signer to deny their involvement in the document. This feature adds an extra layer of security, especially in legal settings where proof of signature is crucial.

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Apryse SDK Benefits

Using the Apryse SDK offers a range of advantages for incorporating e-signatures into your JavaScript applications. Some of these benefits include:

  • Importing signature fields via XFDF/FDF
  • Exporting signature data via XFDF/FDF
  • Built-in support for PKI signing and digital certificates (PFX)
  • Custom signature handlers for enhanced flexibility
  • Signing with images, ink annotations, or custom appearances

How E-Signatures Work

E-signatures generate a unique value, or hash, from a combination of the document data and the private key. During verification, the document data and public key are used to generate the same hash. If the hashes match, it indicates that the data remains intact, and the e-signature is valid.

E-Signature Diagram

E-Signatures vs. E-Signatures Annotations

It’s important to differentiate between e-signatures and e-signature annotations. While e-signatures uniquely identify the author and any document alterations, e-signature annotations lack this level of security. E-signature annotations only serve as annotations in the document without additional identifiable information about the creator.

The Role of Certificate Authorities (CAs)

Certificate Authorities (CAs) act as trusted third parties in cryptographic digital signature setups. They issue digital certificates containing the public key and owner identity. The private key, on the other hand, remains secret and belongs to the user who generated the key pair. The certificate validates that the public key belongs to the entity mentioned in the certificate.

CA Diagram

CAs play a crucial role in verifying the credentials of applicants, ensuring that users and relying parties can trust the information in the certificates. By certifying the identities of individuals, organizations, servers, or other entities, CAs establish trust in the digital landscape.

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Public Key Infrastructure (PKI)

To ensure the verifiability of public key owners, a Public Key Infrastructure (PKI) is often used. PKIs validate the public key owner using a CA. As public keys validate cryptographic signatures, the combination of digital signatures and CAs works together to authenticate the owner and the data.

The Need for Certificate Authorities

Although CAs are necessary in scenarios involving third-party entities, they are not always required for digital signatures. Self-signed certificates can be used in digital signature workflows, as demonstrated in our digital signature sample and web viewer demo. However, it is the responsibility of users to utilize CAs if required for their specific use cases.

Expiration and Revocation of Signatures

Certificates used for signing documents have an expiration date. After this date, signatures placed with such certificates will eventually expire. In contrast, certificate revocation occurs when a certificate is deemed invalid before its expiry. Revoked certificates are listed on a Certificate Revocation List (CRL), indicating their invalidity. This balance between expiration and revocation ensures that signatures are valid for a predefined period, considering both the expiration date and the absence of revocation at the time of viewing the document.

Ensuring Signature Validity with Document Timestamping

To maintain the validity of signatures beyond the certificate expiration or revocation timeframe, Document Timestamping (DTS) can be employed. DTS involves a third-party trust provider, often a Certificate Authority, certifying the secure timestamp of a certificate’s validation. This allows applications to check if the certificate was valid at the time of signing, even if it has expired or been revoked.

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Long Term Validation (LTV)

For archival purposes and the extended validation of signatures, Long Term Validation (LTV) is recommended. LTV ensures that even if the CRL responder of a Certificate Authority is no longer active, applications can still validate signatures based on the time they were applied. It’s worth mentioning that DTS is often used alongside LTV, although they are separate features with distinct functions.

Leveraging WebViewer’s JavaScript PDF Library

WebViewer’s JavaScript PDF library provides a built-in signature tool that enables users to create signature annotations. These signatures are essentially freehand or ink annotations according to the PDF specification. With WebViewer, you can preview, save, and apply default signatures seamlessly.

Additionally, WebViewer supports digital signatures, allowing you to digitally sign and certify PDF documents. Check out our digital signature sample for a live demonstration.

The Security Advantage of Digital Signatures

Digital signatures, with their asymmetric cryptography, offer an extra layer of security compared to signature annotations. While signature annotations are superficial and can move around the document, digital signatures provide robust protection against tampering and unauthorized alterations.

Building a Signing Application with Apryse

Apryse enables the development of powerful signing applications that facilitate document signing, signature placement, and reviewing signed documents. By leveraging React-Redux and Firebase along with Apryse PDF SDK, you can streamline development and expedite time-to-market. Visit our GitHub repo for full source code and examples.

If you’re interested in utilizing the built-in signature tool or interacting with signature form fields and APIs, we have you covered. Whether you want to digitally sign or certify a PDF document, Apryse has the tools and functionality you need.

Final Thoughts

E-signatures in JavaScript offer a secure and efficient method for signing and validating digital documents. With the power of Apryse SDK and WebViewer’s JavaScript PDF library, the possibilities are endless. Embrace the future of e-signatures and streamline your document workflows with confidence.