Browsing by Author "Shen, Shiuan-Tzuo"

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An Effective Integrity Check Scheme for Secure Erasure Code-Based Storage Systems
(2015-09-01)
Shen, Shiuan-Tzuo
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Lin, Hsiao-Ying
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Tzeng, Wen-Guey
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資訊工程學系
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Department of Computer Science
In the application of cloud storage, a user no longer possesses his files in his local depository. Thus, he is concerned about the security of the stored files. Data confidentiality and data robustness are the main security issues. For data confidentiality, the user can first encrypt files and then store the encrypted files in a cloud storage. For data robustness, there are two concerns: service failure, and service corruption. We are concerned about data robustness in cloud storage services. Lin and Tzeng proposed a secure erasure code-based storage system with multiple key servers recently. Their system supports a repair mechanism, where a new storage server can compute a new ciphertext from the ciphertexts obtained from the remaining storage servers. Their system considers data confidentiality in the cloud, and data robustness against storage server failure. In this paper, we propose an integrity check scheme for their system to enhance data robustness against storage server corruption, which returns tampered ciphertexts. With our integrity check scheme, their storage system can deal with not only the problem of storage server failure, but also the problem of storage server corruption. The challenging part of our work is to have homomorphic integrity tags. New integrity tags can be computed from old integrity tags by storage servers without involvement of the user\'s secret key or backup servers. We prove the security of our integrity check scheme formally, and establish the parameters for achieving an overwhelming probability of a successful data retrieval.
Delegable Provable Data Possession for Remote Data in the Clouds
(2011)
Shen, Shiuan-Tzuo
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Tzeng, Wen-Guey
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資訊工程學系
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Department of Computer Science
Many storage systems need to do authorized verification for data integrity. For example, a user stores his data into cloud storage servers and shares his data with his friends. They check data integrity periodically to ensure data intact. However, they don't want a stranger to check data integrity on their data. Therefore, public verification is undesired in this situation. The user can share his private key to his friends for private verification. However, his friends may reveal his private key to others. In this paper, we proposed the delegable provable data possession (delegable PDP) model to solve this problem. Delegable PDP allows a user to control who can check data integrity of his data, and guarantee that delegated verifiers cannot re-delegate this verification capability to others. Delegable PDP enjoys advantage of authorized verification and convenience of public verification. We define a delegable PDP model and provide a construction for it. User U generates verifiable tags of his data and the delegation key dk(upsilon ->nu) for delegated verifier nu, upsilon uploads his data, tags, and dk(upsilon ->nu) to storage servers. When integrity check, storage servers can use dku v to transform U's tags into the form that V can verify with his private key sky. Our model allows U to revoke V's verification capability by removing dku v from storage servers directly. We prove our protocol secure in the random oracle model. Our protocol achieves proof unforgeability, proof indistinguishability, and delegation key unforgeability.
Toward Data Confidentiality via Integrating Hybrid Encryption Schemes and Hadoop Distributed File System
(2012-01-01)
Lin, Hsiao-Ying
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Shen, Shiuan-Tzuo
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Tzeng, Wen-Guey
;
Lin, Bao-Shuh P.
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資訊工程學系
With the increasing popularity of cloud computing, Hadoop has become a widely used open source cloud computing framework for large scale data processing. However, few studies have been done to enhance data confidentiality of Hadoop against storage servers. In this paper, we address the data confidentiality issue by integrating hybrid encryption schemes and the Hadoop distributed file system (HDFS). We propose and implement two integrations, HDFS-RSA and HDFS-Pairing, as extensions of HDFS. Experiments are conducted to demonstrate the performance overhead of HDFS-RSA and HDFS-Pairing. Our integrations provide alternatives toward achieving data confidentiality for Hadoop.
Unique Signature with Short Output from CDH Assumption
(2015)
Shen, Shiuan-Tzuo
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Rezapour, Amir
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Tzeng, Wen-Guey
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資訊工程學系
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Department of Computer Science
We give a simple and efficient construction of unique signature on groups equipped with bilinear map. In contrast to prior works, our proof of security is based on computational Diffie-Hellman problem in the random oracle model. Meanwhile, the resulting signature consists of only one group element. Due to its simplicity, security and efficiency, our scheme is suitable for those situations that require to overcome communication bottlenecks. Moreover, the unique signature is a building block for designing chosen-ciphertext secure cryptosystems and verifiable random functions, which have found many interesting applications in cryptographic protocol design.
Weave ElGamal Encryption for Secure Outsourcing Algebraic Computations Over Z(p)
(2017-01)
Chen, Yi-Ruei
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Shen, Shiuan-Tzuo
;
Tzeng, Wen-Guey
;
資訊工程學系
;
Department of Computer Science
This paper addresses the secure outsourcing problem for large-scale matrix computation to a public cloud. We propose a novel public-key weave ElGamal encryption (WEE) scheme for encrypting a matrix over the field Z(p). The scheme has the echelon transformation property. We can apply a series of elementary row/column operations to transform an encrypted matrix under our WEE scheme into the row/column echelon form. The decrypted result matches the result of the corresponding operations performed on the original matrix. For security, our WEE scheme is shown to be entry irrecoverable for non-zero entries under the computational Diffie-Hellman assumption. By using our WEE scheme, we propose five secure outsourcing protocols of Gaussian elimination, Gaussian-Jordan elimination, matrix determinant, linear system solver, and matrix inversion. Each of these protocols preserves data privacy for clients (data owners). Furthermore, the linear system solver and matrix inversion protocols provide a cheating-resistant mechanism to verify correctness of computation results. Our experimental result shows that our protocols gain efficiency significantly for an outsourcer. Our outsourcing protocol solves a linear system of n = 1,000 equations and in = 1,000 unknown variables about 472 times faster than a non-outsourced version. The efficiency gain is more substantial when (n, m) gets larger. For example, when n = 10,000 and m = 10,000, the protocol can solve it about 56,274 times faster. Our protocols can also be easily implemented in parallel computation architecture to get more efficiency improvement.