Have you ever heard of XAdES? There are multiple signature formats due to historical reasons, how eSignatures have been introduced into existing document formats along with features added over time.

What is XAdES format?

XAdES stands for XML Advanced Electronic Signature, a set of extensions to the XML-DSig recommendations.

It is encoded in a human-readable and machine-readable textual format (Extensible Markup Language) and can be used in many different corporate environments.

In addition, it allows you to sign any type of electronic document, such as PNG or JPEG images, multimedia files (mp3), binary data (such as an .exe file), PDF documents and SEPA transactions.

Types of extensions

Different extensions were developed to meet the needs and scenarios of this signature format. Therefore, they are not ordered from lowest to highest degree of robustness, reliability or security.

  • XAdES-BES: Basic form that simply complies with the legal requirements of the Advanced Electronic Signature Directive.
    XAdES-EPES: Adds information about the signature policy XAdES-T (timestamp): Adds a timestamp field to protect against repudiation
    XAdES-C (complete): Adds references to the certificates and revocation lists used for signed documents to allow off-line verification and validation in the future (but does not store the data itself).
  • XAdES-X (extended)Includes time-stamp to counter the risk that any keys used in the certificate chain or in the revocation status information may be compromised.
  • XAdES-X-L (extended long-term): This is a variation of the previous format in which certificates (public key only) and revocation lists are added to the signed documents to allow future verifications even if the original sources (certificate lookup or revocation lists) are not available.
  • XAdES-A (archiving): Includes additional time-stamps. An expiration period is set for the digital signature and once this time has elapsed, it is eSigned again. An ideal situation for this format are documents with long validity (e.g., mortgages, university degrees, etc)

What makes it different from other types of formats?

The choice between one or the other will depend on the data or type of documents you need to sign and what you intend to do with them once they are electronically signed.

Next, we will discuss other formats that are also available in our solutions:

  • PAdES: Comprises a set of restrictions and extensions for PDF and ISO 32000-1, thus making it suitable for advanced electronic signatures. By default, the signature is always embedded within the PDF document and can only be read by humans. Therefore, this option is not suitable in case the data must also be readable by a computer.
  • CAdES: (CMS Advanced Electronic Signatures) is a set of signed data extensions with cryptographic message syntax (CMS) making it suitable for advanced electronic signatures. A significant feature of this format is that electronically signed documents can remain valid for long periods of time, even if the underlying cryptographic algorithms break.
User performs biometric signature in XaDES format

If you still aren’t sure which format would work best for your business please tell us about your e-signature project and we will get back to you as soon as possible.

Viafirma Documents: A comprehensive, secure solution that supports XAdES

From the backend of Viafirma Documents software, users can add further legal evidence to the document for signature to increase the legal validity of the process.

For face-to-face scenarios we recommend using biometric signatures. They must be performed correctly and using specific devices for capturing biometric data (e.g., Wacom, Adonit, etc.). In addition, the advanced options include a drop-down menu to choose between the available XaDES signature formats.


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