During the current worldwide pandemic and uncertain times, it is important to give the people living in Austria step by step a feeling of safety. The project "QualiSig" of A-Trust GmbH in cooperation with the Donau-Universität Krems, Semotec GmbH and with consulting from Jelurida Swiss SA would like to ensure that security in the field of digital communication is guaranteed. The aim of the project is to solve problems in the field of communication, which have arisen or become immanent due to the COVID-19 situation, through the specific combination of legally valid digital signatures (such as the "mobile-phone signature" operated by A-Trust) and modern Blockchain technologies (such as the Blockchains "Ardor" and "Nxt"). The following questions, among others, can be clearly resolved: Who has issued the information? Who may open the information? Is the recipient also the person he/she claims to be? Has the information itself been altered or forged? And what authorization is given to a person and by whom was it granted? The identity is made verifiable by using an eIDAS-compliant digital signature. Thanks to Blockchain technologies and state-of-the-art encryption techniques, the storage of sensitive data is not tied to a central location and no "cloud services" from external providers are required. The access to the respective personal data is only in the hands of those involved who should have access to it. And citizens also have the possibility to be an active part of the Blockchain themselves, e.g. simply with their mobile phone or their standard PC. The "QualiSig" solution addresses the following use cases: The verification by citizens of people performing door-to-door activities, such as taking blood for an antibody test, a non-announced PCR test in areas where COVID-19 cases have increased, or the control of quarantine measures. The test persons can identify themselves with a QR Code, which leads to a confirmation that can be checked by citizens. A secure communication between authorities and governmental institutions with citizens in the area of personal communication (e.g. transmission of sensitive data). The possibility to publish general information "Fake-News-verified". This means that the originator(s) of the messages are verifiable, and the texts cannot be changed, only "updates", which in turn must be signed, can be added. The combination of different data sets such as an air ticket and a signed health certificate. In this case it is indicated that there is a valid health certificate and the "basic data" for this will be made visible. However, no further personal data will be disclosed. These prototypes can be adapted and used for the appropriate purpose by the authorities, by agencies commissioned by authorities and by NGOs. Also use cases that are relevant beyond those for the COVID-19 situation can arise from the project.