What are digital signatures?

Digital signatures are like electronic “fingerprints.” They are a specific type of electronic signature (e-signature).

In the form of a coded message, the digital signature securely associates a signer with a document in a recorded transaction. Digital signatures use a standard, accepted format, called Public Key Infrastructure (PKI), to provide the highest levels of security and universal acceptance. PKI involves using a digital certificate for identity verification.


What’s the difference between a digital signature and an electronic signature?

A digital signature is a type of electronic signature that requires a more rigorous level of identity assurance through digital certificates.

The broad category of electronic signatures (e-signatures) encompasses many types of electronic signatures. The category includes digital signatures, which are a specific technology implementation of electronic signatures. Both digital signatures and other e-signature solutions allow you to sign documents and authenticate the signer. However, there are differences in purpose, technical implementation, geographical use, and legal and cultural acceptance of digital signatures versus other types of e-signatures.

In particular, the use of digital signature technology for e-signatures varies significantly between countries that follow open, technology-neutral e-signature laws, including the United States, United Kingdom, Canada, and Australia, and those that follow tiered eSignature models that prefer locally defined standards that are based on digital signature technology, including many countries in the European Union, South America, and Asia. In the European Union, under eIDAS regulation, there are two levels of digital signatures: Advanced Electronic Signature (AES) and Qualified Electronic Signature (QES).

In addition, some industries also support specific standards that are based on digital signature technology.


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How do digital signatures work?

Digital signatures, like handwritten signatures, are unique to each signer. Digital signature solution providers, such as DocuSign, follow a specific protocol called Public Key Infrastructure, or PKI. PKI requires the provider to use a mathematical algorithm to generate two long numbers, called keys. One key is public, and one key is private.

When a signer electronically signs a document, the signature is created using the signer’s private key, which is always securely kept by the signer. The mathematical algorithm acts like a cipher, creating data matching the signed document, called a hash, and encrypting that data. The resulting encrypted data is the digital signature. The signature is also marked with the time that the document was signed. If the document changes after signing, the digital signature is invalidated.

As an example, Jane signs an agreement to sell a timeshare using her private key. The buyer receives the document. The buyer who receives the document also receives a copy of Jane’s public key. If the public key can’t decrypt the signature (via the cipher from which the keys were created), it means the signature isn’t Jane’s, or has been changed since it was signed. The signature is then considered invalid.

To protect the integrity of the signature, PKI requires that the keys be created, conducted, and saved in a secure manner, and often requires the services of a reliable Certificate Authority (CA). Digital signature providers, like DocuSign, meet PKI requirements for safe digital signing.


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Digital signature FAQs

How do I create a digital signature?

eSignature providers, such as DocuSign, that offer solutions based on digital signature technology, make it easy to digitally sign documents. They provide an interface for sending and signing documents online and work with the appropriate Certificate Authorities to provide trusted digital certificates.

Depending upon the Certificate Authority you are using, you may be required to supply specific information. There also may be restrictions and limitations on whom you send documents to for signing and the order in which you send them. DocuSign’s interface walks you through the process and ensures that you meet all of these requirements. When you receive a document for signing via email, you must authenticate as per the Certificate Authority’s requirements and then “sign” the document by filling out a form online.

What is Public Key Infrastructure (PKI)?

Public Key Infrastructure (PKI) is a set of requirements that allow (among other things) the creation of digital signatures. Through PKI, each digital signature transaction includes a pair of keys: a private key and a public key. The private key, as the name implies, is not shared and is used only by the signer to electronically sign documents. The public key is openly available and used by those who need to validate the signer’s electronic signature. PKI enforces additional requirements, such as the Certificate Authority (CA), a digital certificate, end-user enrollment software, and tools for managing, renewing, and revoking keys and certificates.

What is a Certificate Authority (CA)?

Digital signatures rely on public and private keys. Those keys have to be protected in order to ensure safety and to avoid forgery or malicious use. When you send or sign a document, you need assurance that the documents and the keys are created securely and that they are using valid keys. Certificate Authorities (CAs), a type of Trust Service Provider, are organizations that have been widely accepted as reliable for ensuring key security and that can provide the necessary digital certificates. Both the entity sending the document and the recipient signing it must agree to use a given CA.

DocuSign is a CA. This means you can always send a document with a digital signature by using DocuSign as the Certificate Authority. Alternatively, you can use a 3rd party Certificate Authority and still access the rich features of DocuSign cloud services for transaction management. Some organizations or regions rely on other prominent CAs, and the DocuSign platform supports them, as well. These include OpenTrust, which is widely used in European Union countries, and SAFE-BioPharma, which is an identity credential that life science organizations may elect to use.

See the full list of Certificate Authorities we support.

Why would I use a digital signature?

Many industries and geographical regions have established eSignature standards that are based on digital signature technology, as well as specific certified CAs, for business documents. Following these local standards based on PKI technology and working with a trusted certificate authority can ensure the enforceability and acceptance of an e-signature solution in each local market. By using the PKI methodology, digital signatures utilize an international, well-understood, standards-based technology that also helps to prevent forgery or changes to the document after signing.

What digital signature solutions does DocuSign offer?

DocuSign Standards-Based Signatures enable you to automate and manage entire digital workflows using DocuSign’s powerful business capabilities while staying compliant with local and industry eSignature standards, including CFR Part 11 and the EU eIDAS regulation. In the EU, DocuSign delivers all of the signature types defined under eIDAS, including EU Advanced Electronic Signatures (AES) and EU Qualified Electronic Signatures (QES).

Are eSignatures, based on digital signature technology, legally enforceable?

Yes. The EU passed the EU Directive for Electronic Signatures in 1999, and the United States passed the Electronic Signatures in Global and National Commerce Act (ESIGN) in 2000. Both acts made electronically signed contracts and documents legally binding, like paper-based contracts. Since then, the legality of electronic signatures has been upheld many times.

By now, most countries have adopted legislation and regulations modeled after the United States or the European Union, with a preference in many regions for the E.U. model of locally managed, digital signature technology-based eSignatures. In addition, many companies have improved compliance with the regulations established by their industries (e.g., FDA 21 CFR Part 11 in the Life Sciences industry), which has been achieved by using digital signature technology. These country- and industry-specific regulations are continuously evolving, a key example being the Electronic identification and trust services (eIDAS) regulation that was recently adopted in the European Union.

What is a digital certificate?

A digital certificate is an electronic document issued by a Certificate Authority (CA). It contains the public key for a digital signature and specifies the identity associated with the key, such as the name of an organization. The certificate is used to confirm that the public key belongs to the specific organization. The CA acts as the guarantor. Digital certificates must be issued by a trusted authority and are only valid for a specified time. They are required in order to create a digital signature.

What is the difference between Advanced Electronic Signature and Qualified Electronic Signature?

AES and QES are digital signature standards regulated by eIDAS, European Union's regulatory framework for electronic signatures that is adopted by all EU member states.

eIDAS defines the 3 levels of electronic signatures: electronic signature (sometimes referred to as a “simple” signature), advanced electronic signature, and qualified electronic signature, which is the most stringent.

AES adds identity verification. Signatures must be uniquely linked to, and capable of identifying, the signer. The signature record can show evidence of tampering.

QES requires face to face identity verification or the equivalent. It’s the only form of digital signature that European Union law considers as the equivalent of a handwritten signature. They are often used for high-value, regulated, or cross-border agreements.