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Transparent, Distributed, and Replicated Dynamic Provable Data Possession
, 2013
"... With the growing trend toward using outsourced storage, the problem of efficiently checking and proving data integrity needs more consideration. Starting with PDP and POR schemes in 2007, many cryptography and security researchers have addressed the problem. After the first solutions for static data ..."
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With the growing trend toward using outsourced storage, the problem of efficiently checking and proving data integrity needs more consideration. Starting with PDP and POR schemes in 2007, many cryptography and security researchers have addressed the problem. After the first solutions for static data, dynamic versions were developed (e.g., DPDP). Researchers also considered distributed versions of such schemes. Alas, in all such distributed schemes, the client needs to be aware of the structure of the cloud, and possibly pre-process the file accordingly, even though the security guarantees in the real world are not improved. We propose a distributed and replicated DPDP which is transparent from the client’s viewpoint. It allows for real scenarios where the cloud storage provider (CSP) may hide its internal structure from the client, flexibly manage its resources, while still providing provable service to theclient. TheCSPdecides onhow many andwhich serverswill storethedata. Sincetheload is distributed on multiple servers, we observe one-to-two orders of magnitude better performance in our tests, while availability and reliability are also improved via replication. In addition, we use persistent rank-based authenticated skip lists to create centralized and distributed variants of a dynamic version control system with optimal complexity. 1
Practical dynamic proofs of retrievability
, 2013
"... Proofs of Retrievability (PoR), proposed by Juels and Kaliski in 2007, enable a client to store n file blocks with a cloud server so that later the server can prove possession of all the data in a very efficient manner (i.e., with constant computa-tion and bandwidth). Although many efficient PoR sch ..."
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Proofs of Retrievability (PoR), proposed by Juels and Kaliski in 2007, enable a client to store n file blocks with a cloud server so that later the server can prove possession of all the data in a very efficient manner (i.e., with constant computa-tion and bandwidth). Although many efficient PoR schemes for static data have been constructed, only two dynamic PoR schemes exist. The scheme by Stefanov et al. (ACSAC 2012) uses a large of amount of client storage and has a large audit cost. The scheme by Cash et al. (EUROCRYPT 2013) is mostly of theoretical interest, as it employs Oblivious RAM (ORAM) as a black box, leading to increased practical over-head (e.g., it requires about 300 times more bandwidth than our construction). We propose a dynamic PoR scheme with constant client storage whose bandwidth cost is comparable to a Merkle hash tree, thus being very practical. Our construction out-performs the constructions of Stefanov et al. and Cash et al., both in theory and in practice. Specifically, for n outsourced blocks of β bits each, writing a block requires β+O(λ logn) bandwidth and O(β logn) server computation (λ is the se-curity parameter). Audits are also very efficient, requiring β +O(λ2 logn) bandwidth. We also show how to make our scheme publicly verifiable, providing the first dynamic PoR scheme with such a property. We finally provide a very effi-cient implementation of our scheme.
Secure and Constant Cost Public Cloud Storage Auditing with Deduplication
"... Abstract—Data integrity and storage efficiency are two important requirements for cloud storage. Proof of Retrievability (POR) and Proof of Data Possession (PDP) techniques assure data integrity for cloud storage. Proof of Ownership (POW) improves storage efficiency by securely removing unnecessaril ..."
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Cited by 6 (0 self)
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Abstract—Data integrity and storage efficiency are two important requirements for cloud storage. Proof of Retrievability (POR) and Proof of Data Possession (PDP) techniques assure data integrity for cloud storage. Proof of Ownership (POW) improves storage efficiency by securely removing unnecessarily duplicated data on the storage server. However, trivial combination of the two techniques, in order to achieve both data integrity and storage efficiency, results in non-trivial duplication of metadata (i.e., authentication tags), which contradicts the objectives of POW. Recent attempts to this problem introduce tremendous computational and communication costs and have been proven not secure. It calls for a new solution to support efficient and secure data integrity auditing with storage deduplication for cloud storage. In this paper we solve this open problem with a novel scheme based on techniques including polynomialbased authentication tags and homomorphic linear authenticators. Our design allows deduplication of both files and their corresponding authentication tags. Data integrity auditing and storage deduplication are achieved simultaneously. Our proposed scheme is also characterized by constant realtime communication and computational cost on the user side. Public auditing and batch auditing are both supported. Hence, our proposed scheme outperforms existing POR and PDP schemes while providing the additional functionality of deduplication. We prove the security of our proposed scheme based on the Computational Diffie-Hellman problem and the Strong Diffie-Hellman assumption. Numerical analysis and experimental results on Amazon AWS show that our scheme is efficient and scalable. I.
Official arbitration with secure cloud storage application
, 2013
"... Static and dynamic proof of storage schemes have been proposed for use in secure cloud storage scenarios. In this setting, a client outsources storage of her data to a server, who may, willingly or not, corrupt the data (e.g., due to hardware or software failures), or delete infrequently accessed pa ..."
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Cited by 5 (2 self)
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Static and dynamic proof of storage schemes have been proposed for use in secure cloud storage scenarios. In this setting, a client outsources storage of her data to a server, who may, willingly or not, corrupt the data (e.g., due to hardware or software failures), or delete infrequently accessed parts to save space. Most of the existing schemes only solve part of this problem: The client may ask for a cryptographic proof of integrity from the server. But what happens if this proof fails to verify? We argue that in such a case, both the client and the server should be able to contact an official court, providing cryptographic proofs, so that the Judge can resolve this dispute. We show that this property is stronger than what has been known as public verifiability in the sense that official arbitration should handle a malicious client as well. We clearly show this formalization difference, and then present multiple schemes that work for various static and dynamic storage solutions in a generic way. We implement our schemes and show that they are very efficient, diminishing the validity of arguments against their use, where the overhead for adding the ability to resolve such disputes at a court is only 2 ms and 80 bytes for each update on the stored data, using standard desktop hardware. Finally, we note that disputes may arise in many other situations, such as when two parties exchange items (e.g., e-commerce) or agree on something (e.g., contract-signing). We show that it is easy to extend our official arbitration protocols for a general case, including dynamic authenticated data structures.
Proofs of retrievability with public verifiability and constant communication cost
- in cloud,” Proceedings of the ACM ASIACCS-SCC’13
, 2013
"... For data storage outsourcing services, it is important to allow data owners to efficiently and securely verify that the storage sever stores their data correctly. To address this issue, several proof-of-retrievability (POR) schemes have been proposed wherein a storage sever must prove to a verifier ..."
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Cited by 3 (1 self)
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For data storage outsourcing services, it is important to allow data owners to efficiently and securely verify that the storage sever stores their data correctly. To address this issue, several proof-of-retrievability (POR) schemes have been proposed wherein a storage sever must prove to a verifier that all of a client’s data are stored correctly. While existing POR schemes offer decent solutions addressing various practical issues, they either have a non-trivial (linear or quadratic) communication complexity, or only support private verification, i.e., only the data owner can verify the remotely stored data. It remains open to design a POR scheme that achieves both public verifiability and constant communication cost simultaneously. In this paper, we solve this open problem and propose the first POR scheme with public verifiability and constant communication cost. In our proposed scheme, the message exchanged between the prover and verifier is composed of a constant number of group elements. Different from existing private POR constructions, our scheme allows public verification and releases the data owners from burden of staying online. Thorough analysis shows that our proposed scheme is efficient and practical. We prove the security of our scheme based on the Computational Diffie-Hellman Problem, the Strong Diffie-Hellman assumption and the Bilinear Strong Diffie-Hellman assumption.
Efficient Dynamic Provable Possession of Remote Data via Balanced Update Trees
"... The emergence and availability of remote storage providers prompted work in the security community that allows a client to verify integrity and availability of the data she outsourced to an untrusted remove storage server at a relatively low cost. Most recent solutions to this problem allow the clie ..."
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Cited by 2 (0 self)
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The emergence and availability of remote storage providers prompted work in the security community that allows a client to verify integrity and availability of the data she outsourced to an untrusted remove storage server at a relatively low cost. Most recent solutions to this problem allow the client to read and update (insert, modify, or delete) stored data blocks while trying to lower the overhead associated with verifying data integrity. In this work we develop a novel and efficient scheme, computation and communication overhead of which is orders of magnitude lower than those of other state-of-the-art schemes. Our solution has a number of new features such as a natural support for operations on ranges of blocks, and revision control. The performance guarantees that we achieve stem from a novel data structure, termed balanced update tree, and removing the need to verify update operations.
Towards Efficient Proofs of Retrievability
"... Proofs of Retrievability (POR) is a cryptographic formulation for remotely auditing the integrity of files stored in the cloud, without keeping a copy of the original files in local storage. In a POR scheme, a user Alice backups her data file together with some authentication data to a potentially d ..."
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Cited by 2 (2 self)
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Proofs of Retrievability (POR) is a cryptographic formulation for remotely auditing the integrity of files stored in the cloud, without keeping a copy of the original files in local storage. In a POR scheme, a user Alice backups her data file together with some authentication data to a potentially dishonest cloud storage server Bob. Later, Alice can periodically and remotely verify the integrity of her data file using the authentication data, without retrieving back the data file. Besides security, performances in communication, storage overhead and computation are major considerations. Shacham and Waters (Asiacrypt ’08) gave a fast scheme with O(sλ) bits communication cost and a factor of 1/s file size expansion where λ is the security parameter. In this paper, we incorporate a recent construction of constant size polynomial commitment scheme (Kate, Zaverucha and Goldberg, Asiacrypt ’10) into Shacham and Waters scheme. The resulting scheme requires O(λ) communication bits (particularly, 920 bits if a 160 bits elliptic curve group is used or 3512 bits if a 1024 bits modulo group is used) per verification and a factor of 1/s file size expansion. Experiment results show that our proposed scheme is indeed efficient and practical. Our security proof is based on Strong Diffie-Hellman Assumption.
Hasan,” Provable MultiCopy Dynamic Data Possession in Cloud Computing Systems
- IEEE Transaction on Information Forensics and Security
, 2015
"... Abstract-Increasingly more and more organizations are opting for outsourcing data to remote cloud service providers (CSPs). Customers can rent the CSPs storage infrastructure to store and retrieve almost unlimited amount of data by paying fees metered in gigabyte/month. For an increased level of sc ..."
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Abstract-Increasingly more and more organizations are opting for outsourcing data to remote cloud service providers (CSPs). Customers can rent the CSPs storage infrastructure to store and retrieve almost unlimited amount of data by paying fees metered in gigabyte/month. For an increased level of scalability, availability, and durability, some customers may want their data to be replicated on multiple servers across multiple data centers. The more copies the CSP is asked to store, the more fees the customers are charged. Therefore, customers need to have a strong guarantee that the CSP is storing all data copies that are agreed upon in the service contract, and all these copies are consistent with the most recent modifications issued by the customers. In this paper, we propose a map-based provable multicopy dynamic data possession (MB-PMDDP) scheme that has the following features: 1) it provides an evidence to the customers that the CSP is not cheating by storing fewer copies; 2) it supports outsourcing of dynamic data, i.e., it supports block-level operations, such as block modification, insertion, deletion, and append; and 3) it allows authorized users to seamlessly access the file copies stored by the CSP. We give a comparative analysis of the proposed MB-PMDDP scheme with a reference model obtained by extending existing provable possession of dynamic single-copy schemes. The theoretical analysis is validated through experimental results on a commercial cloud platform. In addition, we show the security against colluding servers, and discuss how to identify corrupted copies by slightly modifying the proposed scheme.
FlexDPDP: FlexList-based Optimized Dynamic Provable Data Possession
"... With popularity of cloud storage, efficiently proving the integrity of data stored at an untrusted server has become significant. Authenticated Skip Lists and Rank-based Authenticated Skip Lists (RBASL) have been used in cloud storage to provide support for provable data update operations. In a dyna ..."
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Cited by 2 (1 self)
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With popularity of cloud storage, efficiently proving the integrity of data stored at an untrusted server has become significant. Authenticated Skip Lists and Rank-based Authenticated Skip Lists (RBASL) have been used in cloud storage to provide support for provable data update operations. In a dynamic file scenario, an RBASL falls short when updates are not proportional to a fixed block size; such an update to the file, however small, may translate to O(n) many block updates to the RBASL, for a file with n blocks. To overcome this problem, we introduce FlexList: Flexible Length-Based Authenticated Skip List. FlexList translates even variable-size updates to O(u) insertions, removals, or modifications, where u is the size of the update divided by the block size. We present various optimizations on the four types of skip lists (regular, authenticated, rank-based authenticated, and FlexList). We compute one single proof to answer multiple (non-)membership queries and obtain efficiency gains of 35%, 35 % and 40 % in terms of proof time, energy, and size, respectively. We also deployed our implementation of FlexDPDP (DPDP with FlexList instead of RBASL) on PlanetLab, demonstrating that FlexDPDP performs comparable to the most efficient static storage scheme (PDP), while providing dynamic data support.
Towards efficient proof of retrievability in cloud storage
- In ASIACCS ’12: Proceedings of the 7th ACM Symposium on Information, Computer and Communications Security (Full Paper
, 2011
"... Abstract. Proofs of Retrievability (POR) is a cryptographic method for remotely auditing the integrity of files stored in the cloud, without keeping a copy of the original files in local storage. In a POR scheme, a user Alice backups her data file together with some authentication data to a potentia ..."
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Abstract. Proofs of Retrievability (POR) is a cryptographic method for remotely auditing the integrity of files stored in the cloud, without keeping a copy of the original files in local storage. In a POR scheme, a user Alice backups her data file together with some authentication data to a potentially dishonest cloud storage server Bob. Later, Alice can periodically and remotely verify the integrity of her data stored with Bob using the authentication data, without retrieving back the data file during a verification. Besides security, performances in communication, storage overhead and computaton are major considerations. Shacham and Waters [1] gave a fast scheme with O(s) communication bits and a factor of 1/s file size expansion. Although Ateniese et al. [2] achieves constant communication requirement with the same 1/s storage overhead, it requires intensive computation in the setup and verification. In this paper, we incorporate a recent construction of constant size polynomial commitment scheme into Shacham and Waters [1] scheme. The resulting scheme requires constant communication bits (particularly, 720 bits if elliptic curve is used or 3312 bits if a modulo group is used) per verification and a factor of 1/s file size expansion, and its computation in the setup and verification is significantly reduced compared to Ateniese et al. [2]. Essentially, Ateniese et al. [2] requires one group multiplication per each bit of the data file in the setup, while the proposed scheme requires one group multiplication per each chunk of data bits (160 bits per chunk if elliptic curve is used or 1024 bits per chunk if modulo group is used). The experiment results show that our proposed scheme is indeed efficient and practical. Our security proof is based on Strong Diffie-Hellman Assumption.
