As industries increasingly adopt digital twins to enhance efficiency and decision-making, ensuring the authenticity, integrity, and traceability of digital twin data has become a critical challenge. A digital passport provides a secure and standardized framework for managing essential data, linking a physical asset to its digital counterpart through a unique identifier. This paper introduces a novel concept: a digital passport for digital twins. This digital machine passport is designed to securely encapsulate critical data and models within an Asset Administration Shell. The digital machine passport serves as a comprehensive digital identity, linking the physical asset to its digital twin via a unique identifier, and recording detailed information such as maintenance history, technical specifications, the machine’s digital nameplate or any user-defined data. Leveraging blockchain technology, the digital machine passport ensures authenticity, traceability, and transparency of the digital twin’s data, with every change being securely recorded in a tamperproof audit trail. A key use case explored is the secure handling of environmental parameters for CO \(_2\) emissions prediction, enabling stakeholders to verify with high confidence that the data used is authentic and unaltered. Ultimately, this approach could streamline operational procedures and enhance data security in industrial applications.