Cloud auditing enables the integrity verification of cloud data without the necessity of data retrieval, which significantly promotes the storage service of cloud computing. Auditing with ownership transfer is a variation where both cloud data and the tags for integrity verification can be transferred. In some scenarios, like joint-stock enterprise acquisition and electronic medical records migration, we argue that auditing and transferring data belonging to multiple owners are significantly important. However, to the best of our knowledge, there exists no such protocol in multi-ownership scenarios in the literature. In this paper, we propose a blockchain-based accountable auditing protocol with multi-ownership transfer for the first time. One distinguishable property is the simultaneous achievement of verifiability, accountability and multi-ownership transferability, merely with very little extra cost. Specifically, we construct a novel tag structure based on homomorphic authenticator
Cloud storage service provides a convenient way for users to store massive data. To guarantee the integrity of the outsourced data, provable data possession (PDP) schemes for multi-copy data and multi-cloud have been proposed respectively. To avoid a single point of failure and to increase the security of the outsourced data, many users store multiple copies on multiple cloud servers. However, few protocols support multi-copy data and multi-cloud at the same time. Considering that three entities (third-party auditor, cloud organizer and cloud storage servers) participate in the auditing process, it is difficult for users to locate the position of the faults, including entity position, file position and data block corruption position, when the auditor reports data corruption. In this paper we propose a certificateless multi-copy public auditing protocol in multi-cloud storage, which supports to locate the faults entities and corrupted data blocks. Specifically, instead of relying on a t
Driven by various legal obligations and service requirements, the redactable blockchain was introduced to balance the modifiability and immutability of blockchain technology. However, such a blockchain inevitably generates one or even more acceptable versions for the same block data, enabling malicious full nodes to deceive light/new nodes with old data, and even disrupt the consistency of the blockchain ledger. In this paper, we introduce the concept of verifiable redactable blockchain (VRBC) to provide efficient validity verification for on-chain data. To this end, we design a novel authentication data structure, called blockchain authentication tree (BAT), which employs a chameleon hash function and aggregatable vector commitment to bind continuously-appended blocks. Based on this, we propose an efficient VRBC scheme supporting integrity auditing, which not only allows the light nodes to query and validate on-chain data, but also enables new nodes to check the integrity of the block
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To improve data availability and durability, cloud users would like to store multiple copies of their original files at servers. The multi-copy auditing technique is proposed to provide users with the assurance that multiple copies are actually stored in the cloud. However, most multi-replica solutions rely on Public Key Infrastructure (PKI), which entails massive overhead of certificate computation and management. In this article, we propose an efficient multi-copy dynamic integrity auditing scheme by employing certificateless signatures (named MDSS), which gets rid of expensive certificate management overhead and avoids the key escrow problem in identity-based signatures. Specifically, we improve the classic Merkle Hash Tree (MHT) to achieve batch updates for multi-copy storage, which allows the communication overhead incurred for dynamics to be independent of the replica number. To meet the flexible storage requirement, we propose a variable replica number storage strategy, allowing