Cryptanalysis of ``FS-PEKS: Lattice-based Forward Secure Public-key Encryption with Keyword Search for Cloud-assisted Industrial Internet of Things\u27\u27

In this note, we review lattice-based public-key encryption with the keyword search against inside keyword guess attacks (IKGAs) proposed by Zhang \textit{et al}. in IEEE Transactions on Dependable and Secure Computing in 2021. We demonstrate that this scheme is insecure for IKGAs, although Zhang \textit{et al.} demonstrated a secure proof

Lattice-based Public Key Encryption with Authorized Keyword Search: Construction, Implementation, and Applications

Public key encryption with keyword search (PEKS), formalized by Boneh et al. [EUROCRYPT\u27 04], enables secure searching for specific keywords in the ciphertext. Nevertheless, in certain scenarios, varying user tiers are granted disparate data searching privileges, and administrators need to restrict the searchability of ciphertexts to select users exclusively. To address this concern, Jiang et al. [ACISP\u27 16] devised a variant of PEKS, namely public key encryption with authorized keyword search (PEAKS), wherein solely authorized users possess the ability to conduct targeted keyword searches. Nonetheless, it is vulnerable to resist quantum computing attacks. As a result, research focusing on authorizing users to search for keywords while achieving quantum security is far-reaching. In this work, we present a novel construction, namely lattice-based PEAKS (L-PEAKS), which is the first mechanism to permit the authority to authorize users to search different keyword sets while ensuring quantum-safe properties. Specifically, the keyword is encrypted with a public key, and each authorized user needs to obtain a search privilege from an authority. The authority distributes an authorized token to a user within a time period and the user will generate a trapdoor for any authorized keywords. Technically, we utilize several lattice sampling and basis extension algorithms to fight against attacks from quantum adversaries. Moreover, we leverage identity-based encryption (IBE) to alleviate the bottleneck of public key management. Furthermore, we conduct parameter analysis, rigorous security reduction, and theoretical complexity comparison of our scheme and perform comprehensive evaluations at a commodity machine for completeness. Our L-PEAKS satisfies IND-sID-CKA and T-EUF security and is efficient in terms of space and computation complexity compared to other existing primitives. Finally, we provide two potential applications to show its versatility

Public Key Authenticated Encryption with Keyword Search from LWE

Public key encryption with keyword search (PEKS) inherently suffers from the inside keyword guessing attack. To resist against this attack, Huang et al. proposed the public key authenticated encryption with keyword search (PAEKS), where the sender not only encrypts a keyword, but also authenticates it. To further resist against quantum attacks, Liu et al. proposed a generic construction of PAEKS and the first quantum-resistant PAEKS instantiation based on lattices. Later, Emura pointed out some issues in Liu et al.\u27s construction and proposed a new generic construction of PAEKS. The basic construction methodology of Liu et al. and Emura is the same, i.e., each keyword is converted into an extended keyword using the shared key calculated by a word-independent smooth projective hash functions (SPHF), and PEKS is used for the extended keyword. In this paper, we first analyze the schemes of Liu et al. and Emura, and point out some issues regarding their construction and security model. In short, in their lattice-based instantiations, the sender and receiver use a lattice-based word independent SPHF to compute the same shared key to authenticate keywords, leading to a super-polynomial modulus $q$; their generic constructions need a trusted setup assumption or the designated-receiver setting; Liu et al. failed to provide convincing evidence that their scheme satisfies their claimed security. Then, we propose two new lattice-based PAEKS schemes with totally different construction methodology from Liu et al. and Emura. Specifically, in our PAEKS schemes, instead of using the shared key calculated by SPHF, the sender and receiver achieve keyword authentication by using their own secret key to sample a set of short vectors related to the keyword. In this way, the modulus $q$ in our schemes could be of polynomial size, which results in much smaller size of the public key, ciphertext and trapdoor. In addition, our schemes need neither a trusted setup assumption nor the designated-receiver setting. Finally, our schemes can be proven secure in stronger security model, and thus provide stronger security guarantee for both ciphertext privacy and trapdoor privacy

Adaptively Secure Computationally Efficient Searchable Symmetric Encryption

Searchable encryption is a technique that allows a client to store documents on a server in encrypted form. Stored documents can be retrieved selectively while revealing as little information as\ud possible to the server. In the symmetric searchable encryption domain, the storage and the retrieval are performed by the same client. Most conventional searchable encryption schemes suffer\ud from two disadvantages.\ud First, searching the stored documents takes time linear in the size of the database, and/or uses heavy arithmetic operations.\ud Secondly, the existing schemes do not consider adaptive attackers;\ud a search-query will reveal information even about documents stored\ud in the future. If they do consider this, it is at a significant\ud cost to updates.\ud In this paper we propose a novel symmetric searchable encryption\ud scheme that offers searching at constant time in the number of\ud unique keywords stored on the server. We present two variants of\ud the basic scheme which differ in the efficiency of search and\ud update. We show how each scheme could be used in a personal health\ud record system

Optimal and Efficient Searchable Encryption with Single Trapdoor for Multi-Owner Data Sharing in Federated Cloud Computing

Cloud computing, an Internet based computing model, has changed the way of data owners store and manage data. In such environment, data sharing is very important with more efficient data access control. Issuing an aggregate key to users on data enables and authorizes them to search for data of select encrypted files using trapdoor or encrypted keyword. The existing schemes defined for this purpose do have certain limitations. For instance, Cui et al. scheme is elegant but lacks in flexibility in access control in presence of multiple data owners sharing data to users. Its single trapdoor approach needs transformation into individual trapdoors to access data of specific data owner. Moreover, the existing schemes including that of Cui et al. does not support federated cloud.  In this paper we proposed an efficient key aggregate searchable encryption scheme which enables multiple featuressuch as support for truly single aggregate key to access data of many data owners, federated cloud support,query privacy, controlled search process and security against cross-pairing attack. It has algorithms for setup, keygen, encrypt, extract, aggregate, trapdoor, test and federator. In multi-user setting it is designed to serve data owners and users with secure data sharing through key aggregate searchable encryption The proposed scheme supports federated cloud. Experimental results revealed that the proposed scheme is provably secure withrelatively less computational overhead and time complexity when compared with the state of the art

SHIELD: Scalable Homomorphic Implementation of Encrypted Data-Classifiers

Homomorphic encryption (HE) systems enable computations on encrypted data, without decrypting and without knowledge of the secret key. In this work, we describe an optimized Ring Learning With Errors (RLWE) based implementation of a variant of the HE system recently proposed by Gentry, Sahai and Waters (GSW). Although this system was widely believed to be less efficient than its contemporaries, we demonstrate quite the opposite behavior for a large class of applications. We first highlight and carefully exploit the algebraic features of the system to achieve significant speedup over the state-of-the-art HE implementation, namely the IBM homomorphic encryption library (HElib). We introduce several optimizations on top of our HE implementation, and use the resulting scheme to construct a homomorphic Bayesian spam filter, secure multiple keyword search, and a homomorphic evaluator for binary decision trees. Our results show a factor of 10× improvement in performance (under the same security settings and CPU platforms) compared to IBM HElib for these applications. Our system is built to be easily portable to GPUs (unlike IBM HElib) which results in an additional speedup of up to a factor of 103.5× to offer an overall speedup of 1,035×

Using Attribute-Based Access Control, Efficient Data Access in the Cloud with Authorized Search

The security and privacy issues regarding outsourcing data have risen significantly as cloud computing has grown in demand. Consequently, since data management has been delegated to an untrusted cloud server in the data outsourcing phase, data access control has been identified as a major problem in cloud storage systems. To overcome this problem, in this paper, the access control of cloud storage using an Attribute-Based Access Control (ABAC) approach is utilized. First, the data must be stored in the cloud and security must be strong for the user to access the data. This model takes into consideration some of the attributes of the cloud data stored in the authentication process that the database uses to maintain data around the recorded collections with the user\u27s saved keys. The clusters have registry message permission codes, usernames, and group names, each with its own set of benefits. In advance, the data should be encrypted and transferred to the service provider as it establishes that the data is still secure. But in some cases, the supplier\u27s security measures are disrupting. This result analysis the various parameters such as encryption time, decryption time, key generation time, and also time consumption. In cloud storage, the access control may verify the various existing method such as Ciphertext Policy Attribute-Based Encryption (CP-ABE) and Nth Truncated Ring Units (NTRU). The encryption time is 15% decreased by NTRU and 31% reduced by CP-ABE. The decryption time of the proposed method is 7.64% and 14% reduced by the existing method