Refereed Computation Delegation of Private Sequence Comparison in Cloud Computing

Sequence comparison has been widely used in many engineering systems, such as fuzzy keyword search, plagiarism detection, and comparison of gene sequences. However, when the length of the string is extraordinarily long, like the DNA sequence that contains millions of nucleotides, sequence comparison becomes an intractable work, especially when the DNA database is big and the computation resources are limited. Although the generic computation delegation schemes provide a theoretically feasible solution to this problem, it suffers from severe inefficiency when we directly substitute the general function by the sequence comparison function. In this paper, we focus on refereed computation delegation of sequence comparison and present the refereed computation delegation scheme of sequence comparison using multiple servers. In our scheme, the user can detect the dishonest servers and get the correct answer as long as there is one honest server. The direct application of our scheme is DNA sequence comparison of big gene database in medical system. Meanwhile, our scheme satisfies the security requirement of sequence privacy against the malicious adversaries. Moreover, since neither the fully homomorphic encryption nor the complicated proof systems are used for the problem generation and result verification, our solution clearly outperforms the existing schemes in terms of efficiency. The computation complexity of the user is reduced from O(mn) to O(log(mn)), where m,n are the length of the sequences.