what are the properties of digital signature

What Are the Properties of Digital Signature?

In today’s digital age, ensuring the authenticity and integrity of electronic documents is more important than ever. Digital signatures play a critical role in securing online transactions, communications, and records by verifying the source and guarding against tampering. As more organizations and individuals transition to paperless workflows, understanding the properties of digital signatures becomes essential—especially in the context of compliance with local regulations such as the Electronic Signature Laws in the United States (ESIGN Act), the European Union’s eIDAS Regulation, and specific local provisions across Asia-Pacific regions like Taiwan’s Electronic Signature Act. But what exactly gives a digital signature its legal force and trustworthiness?

In this article, we will break down the core properties of digital signatures and explain how these properties support secure and compliant digital communication.

1. Authentication: Verifying the Signer’s Identity

One of the most important properties of a digital signature is authentication. It ensures that the signer of a document is indeed who they claim to be. This is achieved through public key infrastructure (PKI), where each user has a public and private key pair. The digital signature is created using the signer’s private key—a unique, secure code only the signer holds. When someone receives the signed document, they can use the signer’s public key to verify its authenticity.

In terms of local legal terminology, this feature supports identity verification requirements, such as the “independently verifiable identity” clause within Taiwan’s Electronic Signature Act, and aligns with KYC measures under common financial compliance frameworks like AML (Anti-Money Laundering) regulations.

2. Integrity: Ensuring Content Has Not Been Altered

Another critical property of a digital signature is integrity. Once a document is signed, any changes made to the content—even a single punctuation mark—will render the digital signature invalid. This is due to the hash function involved in digital signing that generates a unique string (the digest) for the original document. If the document changes, so does the hash value.

This tamper-evident nature of a digital signature is especially important in legal disputes, as it provides strong evidence that the document has not been manipulated. In regulatory terms, this satisfies legislative requirements for document preservation and traceability, often mentioned in Asia-Pacific electronic transaction laws such as Japan’s Electronic Book Maintenance Act and Malaysia’s Digital Signature Act 1997.

3. Non-Repudiation: Preventing Denial of Signature

Digital signatures don’t just secure data—they also provide legal assurance that a signer cannot refute their action. This is known as non-repudiation. Once a document has been digitally signed using a verified private key, and witnessed or timestamped, that signature cannot be reasonably denied in a court of law.

In legal frameworks like the United States’ ESIGN Act and the European Union’s eIDAS regulation, proving the intent of the signer is a requirement for enforceability. Similarly, clause definitions found in Taiwan’s national e-signature law specify that a signature must uniquely identify the signer and affirm their association with the signed data.

4. Compliance and Legality: Meeting Local and International Standards

While digital signatures offer strong technical protections, they must also adhere to governing laws and industry standards to be considered legally effective. This includes ISO/IEC 27001 and 32000 for information security and document processing, respectively. It also includes compliance with jurisdiction-specific legislation.

For instance, in Taiwan, only a “qualified certificate-based digital signature” issued by a certified service provider recognized by the government is considered legally enforceable in certain high-value transactions. In the EU, a “qualified electronic signature” (QES) carries the same legal weight as a handwritten signature under eIDAS. Businesses operating internationally must ensure their digital signature systems are compliant with these and related statutes, such as Singapore’s Electronic Transactions Act (ETA) and Australia’s Electronic Transactions Act 1999.

5. Time-Stamping: Recording When the Signature Was Made

Time-stamping complements the use of digital signatures by providing proof of the exact moment a document was signed. This is crucial in cases where deadlines are of legal importance—such as contract signings or compliance reporting. A secure, trusted time-stamp authority (TSA) can provide an irrefutable record, contributing further to the non-repudiation property of the signature.

Section 13 of the Taiwan Electronic Signature Act emphasizes the importance of preserving the time and date when the signature is affixed. Likewise, global standards such as RFC 3161 (Internet X.509 Public Key Infrastructure Time-Stamp Protocol) support the technical implementation of trusted time-stamping for use across jurisdictions.

6. Unique Binding: Linking the Signature to the Contents

A digital signature must be uniquely linked to both the signer and the contents of the document. This “binding” ensures that the signature applies only to the specific message or document signed and cannot be transferred or reused elsewhere. This characteristic is especially vital for business or government documents where content authenticity is critical.

Legally, this satisfies the principle of "document content-linkage integrity,” a terminology found in certain East Asian regulatory guidance that mandates clear, technological linkage between the user action (signature) and the content being approved or consented to.

7. Revocability and Certificate Management

Digital signature systems must offer mechanisms to revoke or update digital certificates, especially when a signer’s credentials are compromised. Certificate Authorities (CAs) maintain Certificate Revocation Lists (CRLs) and use Online Certificate Status Protocol (OCSP) services to ensure real-time legitimacy verification.

This aligns with international compliance standards regarding certificate lifecycle management, which are mandatory in most regional regulations, including China’s Electronic Signature Law, which requires the certificate revocation process to be protected against unauthorized access and tampering.

8. User Consent and Signature Intent Recognition

A vital but sometimes overlooked property of a valid digital signature is the explicit intent of the signer. Systems must present clear prompts or terms to users prior to signing to demonstrate intent. Courts commonly require evidence that the signer fully understood and accepted the contents at the moment of signature—especially in contracts or legally binding agreements.

Under the ESIGN Act and similar legal provisions in Taiwan and Singapore, user intent to sign must be demonstrated through an “act associated with the signature,” which is legally recognized if systems prompt users to agree to terms before signing.

Conclusion

The primary properties of a digital signature—authentication, integrity, non-repudiation, compliance, time-stamping, unique binding, certificate management, and demonstrable intent—form the foundation of trust in the digital world. These properties ensure that digital signatures are secure, legally binding, and widely accepted across both domestic and international jurisdictions.

As businesses continue to digitize their workflows, understanding the legal and technical attributes outlined in local regulations is essential for full compliance and risk mitigation. By adopting a certified digital signature solution that aligns with these key properties, organizations can streamline operations, reduce paperwork, and maintain the highest standards of legal enforceability.

Whether you are operating under the ESIGN Act in the U.S., eIDAS in the EU, or localized laws such as Taiwan’s Electronic Signature Act, digital signatures offer a robust, secure, and legally recognized method for conducting business in the digital era.