Public Key Encryption With Keyword Search Research Articles

A Certificateless Verifiable Bilinear Pair-Free Conjunctive Keyword Search Encryption Scheme for IoMT

With superior computing power and efficient data collection capability, Internet of Medical Things (IoMT) significantly improves the accuracy and convenience of medical work. As most communications are over open networks, it is critical to encrypt data to ensure confidentiality before uploading them to cloud storage servers (CSSs). Public key encryption with keyword search (PEKS) allows users to search for specific keywords in ciphertext and plays an essential role in IoMT. However, PEKS still has the following problems: 1. As a semi-trusted third party, the CSSs may provide wrong search results to save computing and bandwidth resources. 2. Single-keyword searches often produce many irrelevant results, which is undoubtedly a waste of computing and bandwidth resources. 3. Most PEKS schemes rely on bilinear pairings, resulting in computational inefficiencies. 4. Public key infrastructure (PKI)-based or identity-based PEKS schemes face the problem of certificate management or key escrow. 5. Most PEKS schemes are vulnerable to offline keyword guessing attacks, online keyword guessing attacks, and insider keyword guessing attacks. We present a certificateless verifiable and pairing-free conjunctive public keyword searchable encryption (CLVPFC-PEKS) scheme. An efficiency analysis shows that the performance advantage of the new scheme is far superior to that of the existing scheme. More importantly, we provide proof of security under the standard model (SM) to ensure the reliability of the scheme in practical applications.

Efficient public-key searchable encryption against inside keyword guessing attacks for cloud storage

Cloud storage offers data users relief from cumbersome management tasks and enhances overall efficiency. However, while it brings convenience, there is also the risk of privacy breaches. To address this, public-key encryption with keyword search (PEKE) presents a solution that balances efficiency, convenience, and security in the context of cloud storage. Nevertheless, PEKS is vulnerable to inside keyword guessing attacks and algorithm substitution attacks, posing a serious threat to its deployment. Cryptographic reverse firewall technique randomizes incoming messages to effectively defend against both types of attacks mentioned earlier through a gateway. However, this approach requires the gateway to store a random number for each keyword, increasing storage costs and potentially exposing keyword information. In response, we propose an improved scheme that inherits the remarkable properties of the method based on cryptographic reverse firewall. Additionally, the proposed scheme eliminates the need for gateways to store random numbers, reducing the management and storage burdens and supports multiple keywords for one document, a feature more aligned with real-world applications. Furthermore, we prove the security of the scheme, which achieves the same security goals as the existing scheme. Finally, we analyze the scheme s efficiency through theoretical analysis and performance evaluation, which demonstrates its efficiency.

Searchable encryption with randomized ciphertext and randomized keyword search

Abstract The notion of public-key encryption with keyword search (PEKS) was introduced to search over encrypted data without performing any decryption. In this article, we propose a PEKS scheme in which both the encrypted keyword and the trapdoor are randomized so that the cloud server is not able to recognize identical queries a priori. Our scheme is Ciphertext-Indistinguishabiltity secure in the single-user setting and Trapdoor-Indistinguishability secure in the multi-user setting with a stronger security, i.e., with multi-trapdoor.

Controlled Search: Building Inverted-Index PEKS With Less Leakage in Multiuser Setting

The public key encryption with keyword search (PEKS) schemes are mostly applied to small data sets in mail forwarding systems. When retrieving large databases, the typical search mechanism makes them inefficient and impractical. When designing a PEKS scheme, except for remedying the vulnerability of Keyword Guessing Attacks (KGA), other leakage issues such as multi-pattern privacy and forward/backward security are rarely considered, which may lead to information leakage. Moreover, most existing PEKS only consider applications in single-user scenarios, and cannot be directly transferred to multi-user scenarios, which undermines the value of data utilization. To cope with the above concerns, we propose a PEKS scheme based on an inverted index where the bitmap is used to build the index for the first time in PEKS to meet some seemingly conflicting yet desirable characteristics. Firstly, it has high search efficiency under multi-writer and multi-user. Through linear transformation, users quickly retrieve data and control other users’ access to their data without relying on a third party for authentication. Secondly, we prove its security in an enhanced security model that achieves multi-pattern privacy and forward and backward security. It can also resist KGA attacks without a designated tester, which makes it more practical. Finally, it can be extended to achieve search result verification. Compare to the scheme (Zhang et al. ICWS 2016), it has absolute advantages in security and computational cost where the search efficiency is improved by two orders of magnitude.

A lattice-based designated-server public-key authenticated encryption with keyword search

Public-key Encryption with Keyword Search (PEKS) provides an efficient way to search on encrypted cloud data. However, it cannot resist against off-line Inside Keyword Guessing Attacks (IKGA). To alleviate this issue, Huang and Li proposed the Public-key Authenticated Encryption with Keyword Search (PAEKS), which the keyword is also authenticated. However, they do not provide post-quantum security promises. In this paper, we propose the first lattice-based designated-server PAEKS (dPAEKS). We formally define dPAEKS and its security models, and propose a lattice-based construction. It is quantum-resistant under the assumption of learning with errors and the sender authenticated the keyword so it can resist IKGA. Furthermore, we strengthen the security requirement, so that only the designated tester can search the ciphertext. Finally, we compare our scheme with some related schemes to demonstrate its efficiency.

StopGuess: A framework for public-key authenticated encryption with keyword search

Public key encryption with keyword search (PEKS) allows users to search on encrypted data without leaking the keyword information from the ciphertexts. But it does not preserve keyword privacy within the trapdoors, because an adversary (e.g., untrusted server) might launch inside keyword-guessing attacks (IKGA) to guess keywords from the trapdoors. In recent years, public key authenticated encryption with keyword search (PAEKS) has become a promising primitive to counter the IKGA. However, existing PAEKS schemes focus on the concrete construction of PAEKS, making them unable to support modular construction, intuitive proof, or flexible extension. In this paper, our proposal called “StopGuess” is the first elegant framework to achieve the above-mentioned features. StopGuess provides a general solution to eliminate IKGA, and we can construct a bundle of PAEKS schemes from different cryptographic assumptions under the framework. To show its feasibility, we present two generic constructions of PAEKS and their (pairing-based and lattice-based) instantiations in a significantly simpler and more modular manner. Besides, without additional costs, we extend PAEKS to achieve anonymity which preserves the identity of users; we integrate it with symmetric encryption to support data retrieval functionality which makes it practical in resource-constrained applications.

Blockchain-based public key encryption with keyword search for medical data sharing in cloud environment

The cloud-based sharing of electronic health data (EHDs) has great significance in researching diseases, doctors’ diagnoses and various fields. In this paper, we applied the potentiality of both blockchain and public key searchable encryption to build a medical data-sharing platform. In recent years, blockchain has emerged as a promising solution for medical data sharing with security and privacy preservation due to its immutability, decentralization, anonymity and verifiability advantages. Two kinds of blockchains, private blockchain and consortium blockchain, are used in our model. In our model, we have designed a consortium blockchain of preselected users. To achieve data security, access control, privacy preservation and secure search, public key encryption with keyword search (PEKS) technology is used here. According to the security proof, our proposed scheme is indistinguishable under the keyword guessing attack. The outcomes of the performance analysis and comparison simulations reveal that the proposed scheme performs better than other related schemes.

Pairing-free public-key authenticated encryption with keyword search

With the growth of third-party cloud storage services, people often store a large amount of data on the cloud servers. However, to ensure the privacy, the sensitive data need to be encrypted before being uploaded to the cloud. Public-key encryption with keyword search (PEKS) is a promising technique that enables users to search target encrypted data by keywords. Unfortunately, most PEKS schemes are vulnerable to inside keyword guessing attacks (KGA). To solve this issue, Huang and Li introduced the concept of public-key authenticated encryption with keyword search (PAEKS), where the sender not only encrypts a keyword, but also authenticates it. However, our cryptanalysis indicated that the efficiency of most existing PAEKS schemes could be improved. Then, we present a novel pairing-free PAEKS scheme based on elliptic curves in this paper. The security proofs show that our scheme can achieve higher computational efficiency and enhanced security models, namely the multi-ciphertext indistinguishability (MCI) and trapdoor privacy (TP). Furthermore, the comparative results demonstrate the efficiency of our proposed scheme is three to thirteen times higher than that of other PAEKS schemes.

LMCLAEKS: LWE-assisted multi-recipient certificateless authenticated encryption with keyword search

In Industrial Internet of Things (IIoT) environments, interconnected gadgets and sensors produce large-scale, dynamic, and private data by the arrival of the fourth industrial revolution. Such data must be stored by cloud service providers (CSP) and is capable of accessed by consumers. To guarantee data privacy, Public-key Encryption with Keyword Search (PEKS) is a cryptographic primitive designed to resolve this challenge, which is troubled by costly certificate management and key escrow problem. The majority of current PEKS schemes rely on expensive bilinear paring and single-receiver, which are highly vulnerable to keyword guessing attacks (KGA) and have low computational efficiency. Consequently, we propose an Multi-recipient Certificateless Authenticated Encryption with Keyword Search (MCLAEKS) scheme, which has the following advantages: 1) hiding search pattern; 2) data allows multiple consumers; 3) involving no costly bilinear pairing operations; 4) resisting Inside Keyword Guessing Attacks (IKGA). The comparison and analysis of performance indicate that the proposed scheme is more efficient than existing PEKS schemes and is suitable for the IIoT environment.

User-Friendly Public-Key Authenticated Encryption With Keyword Search for Industrial Internet of Things

The Industrial Internet of Things (IIoT) incorporates massive physical devices to collect ambient data. Due to the limited types of equipment in IIoT, most of the data has to be saved on a cloud server before it can be processed and analyzed. The ciphertext generated by traditional encryption techniques is difficult to search in subsequent use. Public-key Encryption with Keyword Search (PEKS) can provide data encryption as well as confidential searching, but traditional PEKS schemes are susceptible to internal keyword guessing attacks (IKGA) caused by the limited space of commonly-used keywords. To address this issue, the cryptographic primitive of Public-key Authenticated Encryption with Keyword Search (PAEKS) was proposed, while most of the existing schemes are not appropriately applied to IIoT for involving time-consuming bilinear pairing operations. In this paper, we first propose a user-friendly PAEKS scheme that totally circumvents bilinear pairing operations during generating keyword ciphertext and trapdoor. Then we prove its multi-ciphertext indistinguishability and trapdoor privacy based on decisional q-ABDHE and CDH assumptions in the random oracle model together with conducting the theoretical and experimental comparisons. The results show that the computational overhead of our proposal is significantly reduced comparing with most existing classical PAEKS schemes without causing other communication costs or security loss. Due to its better performance and security, our scheme is better suited for lightweight devices in the IIoT.

SR-PEKS: Subversion-Resistant Public Key Encryption With Keyword Search

Public key encryption with keyword search (PEKS) provides secure searchable data encryption in cloud storage. Users can outsource encrypted data and keywords to a cloud server, and search target one without disclosing sensitive information. To achieve resistance against off-line keyword guessing attacks, existing practical PEKS schemes employ independent key server(s) to assist users in producing keywords to be encrypted (called server-derived keywords) in an online manner. In this paper, we analyze server-aided PEKS schemes and reveal a potential threat: vulnerability against subversion attacks, where algorithms in server-aided PEKS might be maliciously implemented to undermine security. In a subverted encryption implementation, a subliminal channel is established to control randomness generation such that biased ciphertexts covertly leak plaintext information. We further present a specific subversion attack against generation of server-derived keywords to violate keywords' confidentiality. To address these issues, we propose SR-PEKS, a subversion-resistant PEKS scheme based on cryptographic reverse firewalls (CRF). In SR-PEKS, CRF sanitizes outputs of server-derived keyword generation to resist the presented subversion attack. CRF also participates in a collaborative randomness generation protocol to yield unbiased randomness for encryption, thereby eliminating the subliminal channel. Provable security and high efficiency of SR-PEKS are demonstrated by comprehensive analyses and performance evaluations.

Isoga: An Isogeny-Based Quantum-Resist Searchable Encryption Scheme Against Keyword Guessing Attacks

Driven by cloud computing technologies, public-key encryption with keyword search (PEKS) is becoming a common practice from aspects of the Industrial Internet of Things, smart healthcare, vehicular social networks, and so on. However, a dozen years of PEKS development is accompanied by some security and privacy issues in the encrypted data search and access processes. The keyword guessing attack is a typical user privacy threat model, that is, an adversary could guess the user’s retrieval keyword given a search trapdoor. On the other hand, the emergence of quantum computers make traditional PEKS schemes no longer secure. Although scholars put forward some postquantum secure PEKS schemes, these schemes are based on lattice cryptography with a larger key size. To the best of our knowledge, there is no quantum-resist PEKS scheme established on elliptic curve cryptography. This article utilizes PEKS with designated tester primitive and quantum resistance of isogeny. Then, we put forward a postquantum searchable encryption scheme named Isoga, which fights against keyword guessing attacks. We prove Isoga’s searchable ciphertext security and trapdoor indistinguishability under isogeny-related difficult assumptions. Performance evaluation indicates that the Isoga scheme is more practical in the quantum environment, considering seven schemes’ security properties, communication cost, and computing overload among.

How Can We Achieve Query Keyword Frequency Analysis in Privacy-Preserving Situations?

Recently, significant progress has been made in the field of public key encryption with keyword search (PEKS), with a focus on optimizing search methods and improving the security and efficiency of schemes. Keyword frequency analysis is a powerful tool for enhancing retrieval services in explicit databases. However, designing a PEKS scheme that integrates keyword frequency analysis while preserving privacy and security has remained challenging, as it may conflict with some of the security principles of PEKS. In this paper, we propose an innovative scheme that introduces a security deadline to query trapdoors through the use of timestamps. This means that the keywords in the query trapdoor can only be recovered after the security deadline has passed. This approach allows for keyword frequency analysis of query keywords without compromising data privacy and user privacy, while also providing protection against keyword-guessing attacks through the dual-server architecture of our scheme. Moreover, our scheme supports multi-keyword queries in multi-user scenarios and is highly scalable. Finally, we evaluate the computational and communication efficiency of our scheme, demonstrating its feasibility in practical applications.

Public key authenticated searchable encryption against frequency analysis attacks

To retrieve data in form of encryption, Boneh et al. proposed a primitive called the public key encryption with keyword search (PEKS). Unfortunately, PEKS is inherently vulnerable to the keyword guessing attack (KGA). To resist such an attack, Huang et al. introduced an authenticated version of PEKS (i.e., PAEKS), in which the sender not only encrypts the keyword, but also uses his/her secret key to authenticate it. Since then, many PAEKS schemes have emerged to improve the security model of the PAEKS system.However, none of these PAEKS schemes consider frequency analysis attacks (FAA). This attack works by tabulating the frequency distribution of trapdoors generated by user when searching, i.e., placing trapdoors embedded with the same keyword in the same category and recording the number of trapdoors in each category. These frequencies are then compared with the priori knowledge of the frequency of keyword searched by user to extract the keyword embedded in the trapdoor, thereby corrupting the user's search privacy.This work formally analyzes how frequency analysis attacks lead to the leakage of keyword information of the trapdoor in the PAEKS system. Then, to resist against this attack, we propose the first PAEKS scheme with frequency analysis attack resistance to protect the user's search privacy. In order to simplify the management of the sender/receiver's public keys, we further propose our second PAEKS scheme based on the first scheme. Finally, we show that both of these two schemes are proven secure under static assumptions.

Privacy-Preserving Preselection for Protected Biometric Identification Using Public-Key Encryption With Keyword Search

The efficiency of biometric systems, in particular efficient and accurate biometric identification, is one of the most challenging open problems in biometrics today. Adding to that, biometric data are sensitive data deserving adequate protection. As a solution, this work proposes an efficient privacy-preserving reduction of the computational workload of biometric identification systems using public-key encryption with keyword search (PEKS). For long-term protection of the biometric data, fully homomorphic encryption is applied for template protection. As all applied cryptographic schemes are lattice-based, they also offer post-quantum security. Throughout the system, the recognition accuracy of the unprotected system is preserved. In an evaluation on a public face database, the computational workload of an identification search in the encrypted domain is reduced down to 8.4% compared to an exhaustive search, achieving identification on 1062 subjects in 210 milliseconds. Based on these results, an identification search on 1 million subjects can be estimated at under 3 minutes using off-the-shelf hardware.

A pairing-free certificateless searchable public key encryption scheme for IoMT

To ensure confidentiality, medical information is usually encrypted before it is sent to a third party for processing. Encryption technology can protect the privacy of data, but it limits the ability to search for data. The problem is usually solved by using public key encryption with keyword search (PEKS). Recently, some certificateless PEKS (CPEKS) schemes have been proposed. Not only do they allow users to search encrypted data, but they do not have the problems of certificate management and key escrow. However, they rely on the high-consumption bilinear pairing, and some of them are vulnerable to Inside Keyword Guessing Attacks (IKGA). To address these issues, we design a lightweight CPEKS scheme for the Medical Internet of Things (IoMT) that does not include bilinear pairing. In the random oracle model, our scheme is proved to be secure. The analysis results show that the proposed scheme has better overall performance than the existing schemes according to the security property, computation cost, and communication cost. Finally, an IoMT application scenario of our scheme is given.

Provably secure public key encryption with keyword search for data outsourcing in cloud environments

In recent days, the application of cloud computing has been gaining significant popularity among people. A considerable amount of data are being stored in the cloud server. However, data owners outsource their encrypted data to the cloud for various security reasons. Unfortunately, encrypted data cannot be searched, like plaintext data. So how to search encrypted data is an interesting problem in this era. Many public key encryption with keyword search (PEKS) schemes have been designed in the literature. However, most of them cannot prevent keyword-guessing attacks. In this paper, we develop a provably secure PEKS scheme in the random oracle model. This scheme may be used for secure email access from an email server containing a list of encrypted keywords. The proposed scheme can resist keyword-guessing attacks, and offer ciphertext and trapdoor indistinguishability properties. We use the data owner’s private key during encryption to prevent keyword-guessing attacks. Using the data owner’s public key in the verification phase ensures the resilience of keyword-guessing attacks. Finally, the proposed scheme has been tested on a real testbed, and the results show that it can be used in the cloud computing scenario to search for keywords on encrypted data.

Secure channel free public key authenticated encryption with multi-keyword search on healthcare systems

A significant amount of electronic health records (EHRs) have been kept in the cloud due to the quick development of healthcare information systems. However, storing EHRs in the cloud may raise security and data privacy issues. Because of the privacy of a patient’s medical data, storing it on a cloud server requires encryption. Public-key encryption with keyword search (PEKS) solves the problem of retrieval on ciphertext, thus avoiding the problem of plaintext information leakage. However, most PEKS schemes are susceptible to inside keyword guessing attacks (KGA). Besides, transmitting the trapdoor to the cloud server requires a secure channel, which is impractical in healthcare information systems. Roughly speaking, PEKS does not protect the privacy of trapdoor and it is expensive to establish secure channels. In this paper, we propose a secure-channel free public key authenticated encryption with multi-keyword search (SCF-PAEMKS) scheme. The proposed SCF-PAEMKS scheme supports conjunctive keyword search, meanwhile satisfying multi-ciphertext indistinguishability (MCI) and multi-trapdoor privacy (MTP) simultaneously. The efficiency analysis and experimental results show that our SCF-PAEMKS scheme enjoys a better performance compared with related schemes.

VR-PEKS: A Verifiable and Resistant to Keyword Guess Attack Public Key Encryption with Keyword Search Scheme

Public key encryption with keyword search (PEKS) allows users to perform keyword searches of ciphertext on untrusted cloud storage servers, protecting data privacy while sharing data. However, it faces several security problems in practical applications. First, an attacker can launch a keyword guessing attack to obtain keywords of interest to users, causing the leakage of their sensitive information. Second, untrusted cloud servers may return incorrect or incomplete results. In addition, with the continuous development of quantum computers, existing PEKS schemes face the problem of quantum attacks. Since cloud servers are mostly untrusted, verifiable search has become a hot research topic among scholars. However, most of the current schemes are based on bilinear pairing constructions, which are vulnerable to quantum attacks. To solve these problems, we propose a new ciphertext retrieval scheme based on fully homomorphic encryption (FHE), called VR-PEKS. This scheme implements verifiable search and is able to solve the problems of keyword guessing attacks and quantum attacks. We propose to improve the security of the scheme by using the oblivious pseudorandom function to randomize keywords and then encrypt them using FHE. An encrypted verified index structure is constructed and exposed by the data owner, enabling the data recipient to achieve verification of the correctness and integrity of the retrieved results without relying on a trusted third party. We demonstrate the security of the proposed scheme in a stochastic prediction model, and prove that our scheme satisfies keyword ciphertext indistinguishability and keyword trapdoor indistinguishability under adaptive keyword selection attacks. The comparison shows that our scheme is secure and feasible.

Certificateless Public Key Authenticated Encryption with Keyword Search Achieving Stronger Security

Transforming data into ciphertexts and storing them in the cloud database is a secure way to simplify data management. Public key encryption with keyword search (PEKS) is an important cryptographic primitive as it provides the ability to search for the desired files among ciphertexts. As a variant of PEKS, certificateless public key authenticated encryption with keyword search (CLPAEKS) not only simplifies certificate management but also could resist keyword guessing attacks (KGA). In this paper, we analyze the security models of two recent CLPAEKS schemes and find that they ignore the threat that, upon capturing two trapdoors, the adversary could directly compare them and distinguish whether they are generated using the same keyword. To cope with this threat, we propose an improved security model and define the notion of strong trapdoor indistinguishability. We then propose a new CLPAEKS scheme and prove it to be secure under the improved security model based on the intractability of the DBDH problem and the DDH problem in the targeted bilinear group.