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An improved convolution Merkle tree

Presently, more and more electronic medical records (EMR) are used to replace traditional recording methods. However, there have potential safety hazards in the transmission of EMR because of the personal privacy disclosure. So, how to store, transmit and share EMR effectively and securely has become a research hotspot. Here proposal of an improved Merkle tree based-blockchain EMR storage scheme is presented. The hallmark of the proposed scheme is that we employ the convolutional layer structure to replace the original binary tree structure in the proposed convolution Merkle tree, which can improve efficiency effectively. Experiments show that the number of stored nodes has decreased significantly with the same amount of input data, and the number of the layers of the improved convolution Merkle tree and hash calculated amount are all reduced dramatically. The security and efficiency analysis also illustrates that the proposed scheme can provide a reliable choice for the further development of data storage security in the future.

Blockchain Transaction Systems

The centralized exchange is one of the DeFi applications based on blockchain transaction systems. However, depositing user assets to the exchanges brings the security risks of assets misappropriation. Threshold cryptosystem can effectively solve the drawbacks of centralized hosting by assigning the assets authorization to multiple trustees, but the collusion attack generated by malicious trustees is still unavoidable. This proposed a new dynamic threshold ECDSA signature scheme which is compatible with the current blockchain transaction system. It realizes distributed custody of assets in exchanges and further achieves a dynamic mechanism allowing users to join and drop out to resist collusion attacks. Specifically, we formalize the definition of this system architecture and give its construction based on basic cryptography modules such as ECDSA signature, distributed key generation, and distributed computation. Analysis and experiment results show that our scheme holds protocol security and is more efficient than other threshold ECDSA signature schemes when the threshold is less than 200, which makes it applicable to the assets custody scenarios of exchanges.

The explosive generation of Internet of Things (IoT) data calls for cloud service providers (CSP) to further provide more secure and reliable transmission, storage, and management services. This requirement, however, goes against the honest and curious nature of CSP, to the extent that existing methods introduce the third-party audit (TPA) to check data security in the cloud. TPA solves the problem of unreliable CSP but puts a heavy burden on lightweight users because of the sheer amount of pre-audit data processing work. Here, established an audit model based on a designed binary tree assisted by edge computing, which provides computing capability for the resource-constrained terminals. The data pre-processing task is offloaded to the edge, which reduces the computing load and improves the efficiency of task processing. We propose an improved correlation mechanism between data blocks and nodes on the binary tree so that all nodes on the binary tree can be fully utilized while existing methods use only leaf nodes and thus are required to establish multiple binary trees. Moreover, to improve audit efficiency, the binary tree in the audit process is designed to be self-balanced.

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