Qualified Eletronic Stamp

Ensure the authenticity of your documents

The solution for your most sensitive documents issued in digital format.

Unicks - App Connector

The foundation of trust for your online transactions

With the increase in digital crime, it is increasingly important to guarantee the authenticity of digital documents issued by companies, from invoices, to receipts, to transport documents.

By applying the qualified eletronic stamp to your digital documents, you ensure that the documents that reach your customers are safe and trustworthy.

Thus, your customers will feel more confident when carrying out digital transactions.

Please note that, as of Dezember 31, 2023, in Portugal, according to Decree-Law 28/2019 and with Order No. 8/2022-XXIII, the affixing of a qualified stamp (or equivalent: qualified signature or EDI transmission) becomes mandatory for a fiscally relevant digital document (ex: invoice) to  become valid.

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

The signature is on behalf of an individual, either as a private person or as a legal representative of a corporation.
The stamp is on behalf of a collective entity, namely companies.

How is the Qualified Electronic Stamp placed?

1. The company fills in a form so that Contisystems can ensure the purchase of the certificate, issued by a CA (Certification Authority), on its behalf.

2. The company identifies the approximate volume of documents that it intends to sign (put the seal) so that Contisystems buys from CA the number of seals necessary to start affixing them.

3. When it is necessary to place a seal on a document, this is done in an HSM (Hardware Security Module) without it being necessary for the document to leave the Unicks secure area, only its hash (mathematical algorithm for encryption)

All the advantages that this solution offers you


Applicable to any type of documents.


In the case of invoices, there is no conflict with the existing invoicing system.


Invoice data does not leave the ISO 27001 certified Unicks secure environment.


There is flexibility in the design of the invoice and the introduction of commercial messages.


Send documents to the customer via any digital channel.

The digital storage is done in our own datacentre.

How to identify a document with a qualified electronic stamp?

Hand in hand with security

We rely on robust data security and privacy practices that are an integral part of our product engineering and service delivery principles.
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A safe and legally valid solution for digitizing sensitive processes.

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