For the complete documentation index, see llms.txt. You can also append .md to any page URL to get its markdown version.
Skip to main content
For the complete documentation index, see llms.txt.

For the complete documentation index, see llms.txt

Signing methods

Our Sign API v2 supports two main forms of electronic signatures:

  1. Authentication-based signing (where the signature is backed by a verified authentication event) and
  2. PKI signing (where the signature is cryptographically generated natively by the electronic identity scheme).

Authentication-based signing​

Authentication-based signing supports the use of any type of authentication method provided by Signicat, where the authentication result is used for signing. This ensures a unified output format in accordance with EU specifications, as well as a scalable, responsive signing interface supporting all modern device standards and window sizes.

Authentication-based signing enables you to sign one or more documents by first consenting to the contents of the document(s) and subsequently authenticating yourself using one of a number of eID providers.

As the product relies on authentication, the eID providers do not need to support signing themselves. Our Sign API v2 gathers proof of the signer's actions, i.e. viewing the document(s), consenting to the contents and the authentication itself. The series of proofs is combined with each of the original documents.

The result is a signed XML document (XAdES), which is digitally signed by Signicat. Each original document results in one XAdES document for each signer. The signed documents can also be merged into a final PAdES (PDF Advanced Electronic Signatures) document.

Supported authentication-based signing methods​

PKI signing​

Public Key Infrastructure (PKI) signing allows you to sign documents using the natively available signing capabilities of specific eID providers.

In a PKI signing flow, the signature is cryptographically bound to the document using private keys managed by the eID provider or stored securely on the user's device (such as a hardware security module or smartcard). This produces a highly secure, non-repudiable signature compliant with local regulatory standards. The resulting signature can then be verified directly against the provider's trust infrastructure or packaged into standard PAdES containers.

Supported PKI signing methods​

UI and technical differences​

While standard authentication-based signing offers a uniform UI across methods, the end-user experience with PKI-based signing (PKISIGNING) depends on the provider and document type.

Norwegian BankID​

For Norwegian BankID, the PKI-based signing flow looks similar in the UI to signing with AUTHENTICATION_BASED and selecting only the nbid eID. However, there are significant differences with PKI signing:

  • With PKISIGNING, the system creates signing certificates for Cloud Signature Consortium (CSC) solutions.
  • PKISIGNING provides QES-compliant signatures while AUTHENTICATION_BASED does not.
  • When the authentication is complete, the end-user will see a consent screen where they must give their consent before being redirected back to the signing interface or to the redirectUri defined in the signing session.

Swedish BankID​

The behaviour of the end-user interface for Swedish BankID PKI signing depends on the number and type of documents you are signing.

Signing a single text document​

When signing a single text document, Signicat's signing interface is skipped entirely and the end-user is redirected to the BankID application.

  • The document content (the text to be signed) is displayed directly within the Swedish BankID app. You must provide the text content for the document.
  • You can optionally provide an intention text that appears above the document content. If you do not provide one, the default value "You are about to sign the following document(s):" is displayed.

The following is an example of the BankID application view for text documents:

Example of the Swedish BankID application view for text signing

Signing multiple documents or PDFs​

When signing multiple documents (all text, all PDFs or a combination), Signicat's signing interface is displayed to the user before they are redirected to the Swedish BankID app.

  • The signing interface shows a preview of the documents to the user.
  • For PDF files, the file preview is not available in the BankID app itself. Instead, you can provide contextual text using the signText field in the SigningSession object. For example: "You are signing the document Agreement.pdf".
  • This contextual text supports Markdown formatting and is displayed in the BankID app. If no text is provided, a default message is shown.

The following is an example of the BankID application view when contextual text is provided for a PDF:

Example of the Swedish BankID application view for PDF signing

On this page