# Blockchain-Enabled Privacy-Preserving Ecosystem for DNA Sequence Sharing
## 1 Introduction  
The rapid advancements in DNA sequencing technologies have significantly enhanced the quality and quantity of genomic data, providing unprecedented opportunities for medical research and personalized healthcare. Large-scale databases such as the National Center for Biotechnology Information (NCBI) [1] have been established to manage the vast quantities of DNA sequence data generated globally. Furthermore, the increasing public interest in DNA sequencing has spurred the growth of commercial services such as 23 andMe [2], which offers personalized genomic analysis to individuals. However, this proliferation of genomic data has also introduced critical challenges related to data privacy and security. DNA sequences contain highly sensitive information, including genetic predispositions to diseases, physical traits, and other personal attributes. This raises significant privacy concerns, as unauthorized access to or misuse of such data could have serious implications [3]. Recognizing the importance of safeguarding personal data, regulatory frameworks such as the European Union's General Data Protection Regulation (GDPR) [4; 5] have been enacted to enforce strict privacy and access rights. These developments have amplified public demand for robust mechanisms to protect DNA sequences, equating their sensitivity to that of other forms of personal data. To address these concerns, an effective access control mechanism for managing DNA sequence data is imperative. Blockchain technology offers a promising solution due to its decentralized, immutable, and secure characteristics, which inherently prevent data tampering and unauthorized access. This research proposes a privacy-preserving DNA sequence sharing ecosystem leveraging blockchain technology to enhance data security and autonomy. The ecosystem consists of two interconnected blockchains: a decentralized identity chain and a DNA sharing chain. The decentralized identity chain facilitates the autonomous management of digital identities through the allocation of personal contracts to users. These contracts enable users to register for various services independently of centralized identity providers, ensuring control and autonomy over their digital identities. The DNA sharing chain, in turn, implements an access control mechanism that allows users to define granular access levels for their DNA segments, specifying target groups for data sharing. To ensure trustworthiness, research institutions participating in the ecosystem must undergo government certification and classification. The primary objective of this ecosystem is to establish a secure and trustworthy environment for DNA sequence sharing, preserving the privacy and autonomy of both individuals and research institutions while advancing medical research. In particular, this work addresses the following research questions: (RQ1) How can blockchain technology be utilized to enable fine-grained, privacy-preserving sharing of DNA sequences among authorized parties? (RQ2) What system architecture and mechanisms are needed to ensure such a solution is scalable, secure, and interoperable with real-world healthcare workflows? To answer these questions, we propose a novel dual-blockchain architecture and implement a working prototype. The main contributions of this work include (1) a two-chain blockchain ecosystem (combining Ethereum and Hyperledger Fabric) that separates identity management from DNA data sharing to improve scalability and privacy; (2) a fine-grained access control mechanism for DNA sequence segments, enabling selective data sharing with granular permissions; (3) an integration of off-chain storage and decentralized identity (DID) to handle large genomic datasets and comply with privacy regulations (e.g., GDPR's right to erasure); and (4) a comprehensive evaluation and comparison with existing approaches, demonstrating improved throughput (up to 10-20 transactions/s) and robust security features. This design extends prior work in decentralized health data sharing (e.g., [PERSON] et al.