Hash Function Based Keyword Searchable Encryption Framework in Cloud Server Using MD5 and MECC

Cloud Computing expands its usability to various fields that utilize data and store it in a common space that is required for computing and the purpose of analysis as like the IoT devices.These devices utilize the cloud for storing and retrieving data since the devices are not capable of storing processing data on its own.Cloud Computing provides various services to the users like the IaaS,PaaS and SaaS.The major drawback that is faced by cloud computing include the Utilization of Cloud services for the storage of data that could be accessed by all the users related to cloud.The use of Public Key Encryptions with keyword search(PEKS)provides security against the untrustworthy third-party search capability on publicly encryption keys without revealing the data’s contents.But the Security concerns of PEKs arise when Inside Keywords Guessing attacks(IKGA),is identified in the system due to the untrusted server presume the keyword in trapdoor.This issue could be solved by using various algorithms like the Certificateless Hashed Public Key Authenticated Encryption with Keyword Search(CL-HPAEKS)which utilizes the Modified Elliptic Curve Cryptography(MECC)along with the Mutation Centred flower pollinations algorithm(CM-FPA)that is used in enhancing the performance of the algorithm using the Optimization in keys.The additional use of Message Digests 5(MD5)hash function in the system enhances the security Level that is associated with the system.The system that is proposed achieves the security level performance of 96 percent and the effort consumed by the algorithm is less compared to the other encryption techniques.

Constructing pairing-free certificateless public key encryption with keyword search

Searchable public key encryption enables a storage server to retrieve the publicly encrypted data without revealing the original data contents.It offers a perfect cryptographic solution to encrypted data retrieval in encrypted data storage systems.Certificateless cryptography(CLC)is a novel cryptographic primitive that has many merits.It overcomes the key escrow problem in identity-based cryptosystems and the cumbersome certificate problem in conventional public key cryptosystems.Motivated by the appealing features of CLC,three certificateless encryption with keyword search(CLEKS)schemes were presented in the literature.However,all of them were constructed with the costly bilinear pairing and thus are not suitable for the devices that have limited computing resources and battery power.So,it is interesting and worthwhile to design a CLEKS scheme without using bilinear pairing.In this study,we put forward a pairing-free CLEKS scheme that does not exploit bilinear pairing.We strictly prove that the scheme achieves keyword ciphertext indistinguishability against adaptive chosen-keyword attacks under the complexity assumption of the computational Diffie-Hellman problem in the random oracle model.Efficiency comparison and the simulation show that it enjoys better performance than the previous pairing-based CLEKS schemes.In addition,we briefly introduce three extensions of the proposed CLEKS scheme.

Private Keyword-Search for Database Systems Against Insider Attacks

The notion of searchable encrypted keywords introduced an elegant approach to retrieve encrypted data without the need of decryption. Since the introduction of this notion, there are two main searchable encrypted keywords techniques, symmetric searchable encryption （SSE） and public key encryption with keyword search （PEKS）. Due to the complicated key management problem in SSE, a number of concrete PEKS constructions have been proposed to overcome it. However, the security of these PEKS schemes was only weakly defined in presence of outsider attacks;therefore they suffer from keyword guessing attacks from the database server as an insider. How to resist insider attacks remains a challenging problem. We propose the first searchable encrypted keywords against insider attacks （SEK-IA） framework to address this problem. The security model of SEK-IA under public key environment is rebuilt. We give a concrete SEK-IA construction featured with a constant-size trapdoor and the proposed scheme is formally proved to be secure against insider attacks. The performance evaluations show that the communication cost between the receiver and the server in our SEK-IA scheme remains constant, independent of the sender identity set size, and the receiver needs the minimized computational cost to generate a trapdoor to search the data from multiple senders.

Secure searchable encryption:a survey

Cloud computing facilitates convenient and on-demand network access to a centralized pool of resources.Currently,many users prefer to outsource data to the cloud in order to mitigate the burden of local storage.However,storing sensitive data on remote servers poses privacy challenges and is currently a source of concern.SE(Searchable Encryption)is a positive way to protect users sensitive data,while preserving search ability on the server side.SE allows the server to search encrypted data without leaking information in plaintext data.The two main branches of SE are SSE(Searchable Symmetric Encryption)and PEKS(Public key Encryption with Keyword Search).SSE allows only private key holders to produce ciphertexts and to create trapdoors for search,whereas PEKS enables a number of users who know the public key to produce ciphertexts but allows only the private key holder to create trapdoors.This article surveys the two main techniques of SE:SSE and PEKS.Different SE schemes are categorized and compared in terms of functionality,efficiency,and security.Moreover,we point out some valuable directions for future work on SE schemes.

A Flaw in the Security Proof of BDOP-PEKS and PEKS-STAT

Provable security has been widely used for analyzing the security of cryptosystems. Its main idea is to reduce the security to some well-defined computational assumption. The reduction process is called the security proof. In this paper, we find a flaw in the security proof of BDOP-PEKS and PEKS-STAT, present a new conclusion for the security of BDOP-PEKS, and give a security proof. The flaw in the security proof of PEKS-STAT can be fixed in the same way. Finally we conclude some steps of security proof, and emphasize that the probability is as important as the construction.