Research On Obfuscation-based Searchable Encryption

At present,governments,enterprises,and individuals start to put their data in the cloud servers to save storage space and system maintenance.In order to guarantee the privacy and security of the data on the cloud servers,the users can use the existing encryption cryptosystem to encrypt the data before put it on the cloud servers.However,if a user wants to find the specific file he need within the extremely large amount of data on the cloud server,it is hard to search the file within the encrypted data.Aiming at this very problem,some cryptographers came up with the searchable encryption technique.Meantime,to solve the problem of sharing encrypted data in cloud storage,proxy re-encryption cryptosystem was brought out,by which the privacy of the data is realized,along with the distribution of decrypted permissions.Combining the searchable encryption and the proxy re-encryption cryptosystem,we can make the applications of cloud storage become more plentiful and convenient.The combination shows positive significance of the development of cloud computation.Our main creative point and contribution is as shown below:1.The current algorithms of public-key searchable encryption scheme are often rather complex,slow in encrypting and decrypting.Moreover,most of them are constructed with bilinear pairings.In this paper we propose a public-key searchable encryption scheme based on indistinguishable obfuscation,which is easier to realize and better in protecting privacy.Although the current indistinguishable obfuscation schemes has a rather long running time,its construction approach keeps improving and its running speed keeps increasing.Therefore,the scheme constructed in this paper is with theoretical significance.In our construction,we first construct a circuit by ELGamal encryption algorithm and a puncturable pseudorandom function with secret key,and obtain another circuit by obfuscating it with an indistinguishable obfuscator to encrypt plaintext file and the key words involved within.2.In most current conditional proxy re-encryption schemes,not only semi-trusted third party is involved in generating the re-encryption secret key,but also bilinear pairings.The disadvantage of the schemes above are the large amount of calculated quantity and a waste of resource which keeps the third party online all time.Aiming at the shortcomings,underlying our construction is the obfuscate technology which constructed the first reencryption obfuscator with keyword search.The same functions of conditional proxy reencryption are realized.Based on the re-encryption obfuscator constructed by Srinivasand and Rangan,in this paper we construct the re-encryption obfuscator with keyword search.The scheme is realize in the group of prime order.First,the encryption algorithm which encrypts plaintext file and the keyword involved within is constructed,and the first layer of ciphertext is generated.The realization of keyword encryption is obtained by a mod p calculation.Then,we construct the searchable re-encryption algorithm.When the keyword search is verified,the corresponding ciphertext is re-encrypted and output.If the keyword search does not pass the verification,the ciphertext will not be output,and the program will be terminated.At last,the searchable re-encryption algorithm can be obfuscated by obfuscation algorithm and the re-encryption obfuscator with keyword search is obtained.In the end of this paper,the property that this scheme satisfies average-case virtual black-box is analyzed along with some efficiency comparison with some other schemes.