With the proliferation of digital transactions, trust is becoming increasingly important, as exemplified by the World Economic Forum’s Data Free Flow with Trust. Digital signatures are utilized to establish trust to prevent spoofing and unauthorized modification of transmitted digital data. However, the extent of trust is limited by jurisdictions, trusted lists and bridge certificate authorities, and does not have international coverage. For this reason, mutual recognition is needed, i.e. trust relationships established across countries. Establishing mutual recognition is complex and time-demanding due to the legislations, systems, and technologies involved. In parallel, electronic signatures consist of complex systems and structures and, thus, focusing on the technical requirements and solutions can enhance mutual recognition processes. The purpose of our approach is to develop a testbed that can verify technical aspects of mutual recognition. This paper describes the concept of the testbed “Hakoniwa” which includes analyzing the requirements, simulating and testing mutual recognition trust services across US, UK, EU and JP.