Lambda Service



What is Lambda Service and why should use it

Lambda Service allows you to create digitally signed PDF documents, which maintain their legal validity even in paper format (print).

The legal validity of the paper document derives from the presence of a special secure QRCode inserted in the PDF signature area.

The content of this QRCode (Lambda Seal) guarantees an inviolable and secure connection between the digitally signed document and the paper copy of the document.

The Lambda platform has an online storage system (Lambda Store) of signed and encrypted documents (AES256); this approach is secure and fully compliant with GDPR.

The connection is manageable by the owners of the documents: the Lambda platform allows the owners of the documents to suspend or revoke the release of the documents and to add an information note on their status.

As an additional option, documents managed by Lambda Service are referenced in the Algorand blockchain. This action notifies the existence of the document when it is signed and inserted in the Lambda platform.

Lambda Seal does not contain a simple link to a document, but a secure data structure, containing the decryption key of the document and a series of other information necessary for its acquisition. Through Lambda Seal it will always be possible to obtain in real time the original signed document (PAdES): nobody will be able to modify or replace your documents, even when printed.

Who needs Lambda Service?

Lambda Service can be used both by Companies/Businesses in a centralized way through the λPes Appliance and automatic digital signature, and by Professionals and small Businesses through a free application for Windows or OSX environments, managing the signature operations with your normal digital signature.

Where are my files stored and why are they safe?

To complement Lambda Service, GT50 offers the Lambda Store(*) file hosting.

The Lambda Store keeps your documents online, encrypted with AES256, the strongest standard encryption algorithm available today.

GT50 doesn’t have the decryption keys, so it can’t access the content of these files, it can only store them; for this reason we talk about “zero knowledge”.

The data is always stored in encrypted form and only those who already have the document in paper form have – through the QRCode present in the graphic area of the signature – the decryption key of the single file.

This mechanism definitely protects the files stored on Lambda Store: even in case of violation of these servers, no one will be able to access the content of your files.

This approach is GDPR compliance.

Who designed and built Lambda Service?

We have been dealing with security for more than twenty years; in 2001 we invented the concept of Digital Stamp and Electronic Marking, becoming the national market leader.

Like the other security products we designed, the Lambda Service platform follows the security standards and implements only standard encryption algorithms.

With data security as its first objective, the platform has been designed in a simple way, just as its implementation is simple and – thanks to the standard encryption and digital signature algorithms used – allows the creation of documents that are inviolable but easily usable by those who are authorized.

Try Lambda Service

Lambda Service can be tested free of charge for a period of 30 (thirty) days using our Windows-based LambdaSign software.

LambdaSign allows you to sign one or more PDF documents and to customize the graphic area of the signature with your own logo or image of a rubber stamp, possibly enriched with information about the signer, taken from the digital signature certificate.

During the test period, the Customer will be able to verify all the Platform’s functionalities; afterwards he will be able to decide whether to transform this test period into a license, completing the registration process and paying the annual subscription to the service, which for each user is €99.00 + V.A.T.

The subscription allows you to manage 500 documents/year and includes a 200MB document space; with this license the documents cannot exceed 4MB in size.

For those who need to manage more documents or more available space or if they have to work on files of particular size, there is the LambdaSignPro version. Go to the contacs page, specify “λSignPro” as the topic and send us your requests.

Register in the demo area of the GT50 Services portal.

After registration you will receive an email to confirm your registration and the link to download the LambdaSign installation software.

Alternatively, you can download LambdaSign directly from here and register in

Integration with Corporate Information Systems

For more information about Lambda Service and its integration in the company ICT environment, go to, specify “λService” as the topic and send us your requests.

(*) Lambda Store is a facility already included in Lambda Service, designed primarily for Professionals or SMEs; Lambda Service can easily use a content provider other than Lambda Store, according to the will of the Customer.