基于盲GDH签名的无记忆模糊关键词搜索

Oblivious Fuzzy Keyword Search Based on Blind GDH Signature

摘要: 在云计算中，用户在计算过程中的数据安全问题已经成为制约云计算发展的一个瓶颈。本文针对云计算中的加密搜索问题，提出一个有效的加密搜索方案。在搜索过程中，为保证用户的数据安全，用户需要隐藏搜索的关键词以及搜索返回的结果。Wakaha Ogata和Kaoru Kurosawa在2004年提出了一个基于盲RSA签名的无记忆关键词搜索(OKS)方案，提供了安全的加密搜索，然而该方案中每个数据文件只能关联一个关键词。本文改进了原方案，我们的方案基于盲GDH签名，同时使无记忆关键词搜索方案可以在一个数据文件中同时关联多个关键词供用户搜索。此外，用户在搜索的过程中，可能因为关键词不能完全匹配而导致搜索失败，针对这一问题我们将该方案扩展为无记忆模糊关键词搜索(OFKS)方案，使得用户能够对模糊关键词进行正确且安全的搜索操作.相比较原来的方案，我们的方案提供了更有效的搜索方式及对模糊关键词搜索的支持。

Abstract: As Cloud Computing becomes prevalent, data privacy has been a bottleneck of Cloud Computing. When using Cloud Computing, users need to implement a large amount of data search. So the security of search is a key point of protecting user’s data privacy. This paper mainly concentrates on the searchable encryption scheme. In order to guarantee the security property, a user needs to hide the keywords and the files he/she wants to search. In 2004 Wakaha Ogata and Kaoru Kurosawa proposed a secure searchable encryption scheme, named as oblivious keyword search (OKS), based on Chaum’s blind signature. However we find their scheme connecting only one keyword with the data file that is encrypting the data file with its keyword. And then if a data file contains several keywords, we need to repeat the encryption with every keyword. This is quite inefficient. We solve this problem by constructing a new OKS scheme from blind signature based on GDH assumption and connect data files with all its possible keywords. Furthermore, when users are searching by keywords, they might fail to get the desire data files, owing to mismatching the exact keywords. Aiming to solve this problem, we extend our scheme to an oblivious fuzzy keyword search (OFKS) scheme, allowing a user securely search data files through fuzzy keywords. Compare to the original scheme, our scheme possesses more practicality and has been fuzzy keyword supported.