Identity-based Encryption Scheme Research Articles

A lattice-based efficient certificateless public key encryption for big data security in clouds

With the advancement of technology and the development of digitization, big data has become an integral component of modern society. Due to the huge volume of big data, users generally upload data to the cloud for storage and computation. Because data in the cloud is beyond the control of users, it faces threats such as data security and personal privacy leakage. To address these concerns and achieve big data security and privacy protection in clouds, data encryption is crucial. Traditional public key encryption involves complex certificate management in a public key infrastructure (PKI). Although the identity-based encryption (IBE) scheme avoids the management of public key certificates, it has issues with key escrows and identity revocation. The certificateless public key encryption (CL-PKE) not only solves the key escrows problem in IBE, but also maintains its advantage of not requiring the use of certificate in PKI, making it suitable for the security protection of big data in clouds. However, most CL-PKE schemes are constructed based on large integer factorization and discrete logarithm problems, which cannot resist quantum computing attacks. Therefore, this paper proposes an efficient lattice-based CL-PKE scheme for big data security in clouds. In addition, the proposed scheme is extended to a lattice-based certificateless proxy re-encryption scheme, facilitating secure big data sharing in clouds. The proposed CL-PKE scheme can resist attacks from both internal and external adversaries, and has been proven to be IND-CPA secure under the learning with errors (LWE) assumption. Experiments have shown that the proposed CL-PKE scheme has lower computational and communication costs. The proposed lattice-based schemes can effectively provide post quantum security for the security and privacy protection of big data in clouds.

Identity-Based Encryption with (Almost) Tight Security in the Multi-instance, Multi-ciphertext Setting

We construct an identity-based encryption (IBE) scheme that is tightly secure in a very strong sense. Specifically, we consider a setting with many instances of the scheme and many encryptions per instance. In this setting, we reduce the security of our scheme to a variant of a simple assumption used for a similar purpose by Chen and Wee (CRYPTO 2013, Springer, 2013). The security loss of our reduction is O(k)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extbf{O} (k)$$\\end{document} (where k\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$k $$\\end{document} is the security parameter). Our scheme is the first IBE scheme to achieve this strong flavor of tightness under a simple assumption. Technically, our scheme is a variation of the IBE scheme by Chen and Wee. However, in order to “lift” their results to the multi-instance, multi-ciphertext case, we need to develop new ideas. In particular, while we build on (and extend) their high-level proof strategy, we deviate significantly in the low-level proof steps.

A lattice-based forward secure IBE scheme for Internet of things

The Internet of Things (IoT) is gaining popularity as it can effectively connect the real world with the Internet. However, security and privacy issues are widely considered the major obstructions to its widespread adoption. Hence, various cryptographic tools (e.g., encryption and signature schemes) have been proposed to build secure and authenticated channels for data communication in IoT. In this work, we investigate the well-known encryption scheme called identity-based encryption (IBE) for IoT-oriented applications. In particular, we are mainly interested in forward-secure IBE (fs-IBE) which could still protect the data transferred in the past when the current secret key stored in the IoT device is stolen. To this end, we propose an fs-IBE scheme which, as far as we know, is the first construction of fs-IBE that can resist quantum attacks. Our scheme is based on the lattice-based hardness assumption namely Learning with Error (LWE), which is widely adopted for designing other quantum-resistant cryptographic schemes. At the core of our design is the minimal cover mechanism in the context of binary tree and we rigorously prove the security of our scheme in the forward-secure, selective ID, chosen-plaintext attack (CPA) model. Besides the post-quantum security, our scheme enjoys comparatively compact ciphertext and secret key, and thus it is suitable for bandwidth-limited IoT communication.

Anonymous hierarchical identity-based encryption with delegated traceability for cloud-based data sharing systems

Cloud-based data sharing systems (DSS) have become prevalent due to their ample storage and convenient access control. To protect sensitive data privacy in DSS, anonymous identity-based encryption (IBE) is a promising approach, enabling encryption using a recipient’s identity as a public key, while preventing identity and data leaks out of ciphertexts. As complete anonymity risks abuse and illegal usage, Blazy et al. introduced the notion called anonymous IBE with traceable identities (AIBET) at ARES’19, allowing users with tracing keys to identify recipients from ciphertexts. Unfortunately, existing AIBET schemes lack tracing key delegation and only consider security in weaker models (i.e., selective-identity attacks and chosen-plaintext attacks), posing risks of inconvenience and user privacy leaks. In this paper, we introduce a novel notion called anonymous hierarchical identity-based encryption with delegated traceability (AHIBEDT) for DSS. We formalize its syntax and define security notions in stronger models (i.e., adaptive-identity attacks and chosen-ciphertext attacks). In addition, we demonstrate that a concrete AHIBEDT scheme can be simply obtained from a hierarchical IBE scheme and a one-time signature scheme. The comparison results indicate that, despite a substantial increase in communication and computational costs, our approach achieves better security and functionality.

FABRIC: Fast and Secure Unbounded Cross-System Encrypted Data Sharing in Cloud Computing

Existing proxy re-encryption (PRE) schemes to secure cloud data sharing raise challenges such as supporting the heterogeneous system efficiently and achieving the unbounded feature. To address this problem, we proposed a fast and secure unbounded cross-domain proxy re-encryption scheme, named FABRIC, which enables the delegator to authorize the semi-trusted cloud server to convert one ciphertext of an identity-based encryption (IBE) scheme to another ciphertext of an attribute-based encryption (ABE) scheme. As the first scheme to achieve the feature mentioned above, FABRIC not only enjoys constant computation overhead in the encryption, decryption, and re-encryption phases when the quantity of attributes increases, but is also unbounded such that the new attributes or roles could be adopted into the system anytime. Furthermore, FABRIC achieves adaptive security under the decisional linear assumption (DLIN). Eventually, detailed theoretical and experimental analysis proved that FABRIC enjoys excellent performance in efficiency and practicality in the cloud computing scenario.

PIRB: Privacy-Preserving Identity-Based Redactable Blockchains with Accountability

In this paper, we propose a privacy-preserving identity-based redactable blockchain (PIRB), the first identity-based redactable blockchain that supports flexible policies while maintaining accountability. Based on digital identities, PIRB enables a knowledge owner to set one policy for a batch of users while preserving policy privacy. Furthermore, similar to state-of-the-art solutions, PIRB draws inspiration from the proxy re-encryption technique to enforce user accountability. The design of PIRB entails addressing two primary technical challenges: firstly, achieving a flexible policy while upholding policy privacy; secondly, establishing accountability measures. To tackle the former challenge, we propose an enhanced identity-based encryption scheme that integrates polynomial function techniques. To address the latter challenge, a distinct identifier is generated for each user and subsequently concealed within the user’s secret key. Specifically, following existing schemes, we present the first scheme PIRB-I to cater to one-way access control scenarios, empowering owners to define access policies for designated editors. Additionally, recognizing the needs on the editor side for owner selection, we enhance PIRB-I through the introduction of matchmaking encryption, thereby supporting bilateral access control in a framework denoted as the second scheme PIRB-II. Notably, PIRB-I and PIRB-II involve a trade-off between computational and communication complexities. Specifically, when contrasted with PIRB-I, PIRB-II facilitates editors in owner selection, thereby mitigating editors’ communication overheads at the cost of increased computational overheads during policy generation and matching. Theoretical analysis demonstrates the inherent trade-off complexity and the resilience exhibited by PIRB-I and PIRB-II against chosen-plaintext attacks. Extensive experimentation on the FISCO blockchain shows that, compared with the state-of-the-art works, PIRB-I and PIRB-II achieve 200 times and 100 times computational efficiency improvements and 50 times and 60 times communication efficiency improvements on average, respectively.

IoT-friendly, pre-computed and outsourced attribute based encryption

The Internet of Things (IoT) and its applications are growing at an unprecedented rate. In such a complex network with an enormous number of nodes, an important challenge is how to securely handle the access control problem. Attribute Based Encryption (ABE) is a powerful and flexible cryptographic primitive to address the challenge of realizing fine-grained access control in many systems. However, using ABE in IoT systems is often problematic due to the heavy computational overhead originating from the bilinear pairing operations and the relatively large key sizes of ABE schemes.This paper deals with this challenge by proposing some solutions to overcome the limitations of using ABE in IoT systems. The contributions of this paper are divided into three parts. In the first part, we propose modified fuzzy identity-based encryption (FIBE) schemes that use fewer optimal ate pairing operations compared to the original FIBE. FIBE is a special case of ABE, in which the access structure simplifies to a threshold gate. We also introduce a new security notion named the Conditional Chosen Ciphertext Attack-2 (Conditional CCA-2) selective security which is stronger than the CPA selective security notion. We prove that the proposed FIBE schemes have Conditional CCA-2 selective security, under the Asymmetric Decisional Modified Bilinear Diffie–Hellman (ADMBDH) assumption. In the second part, we proposed Key Policy Attribute Based Encryption (KP-ABE) schemes that use fewer pairing operations compared to the previous KP-ABE schemes. Our FIBE and KP-ABE schemes use elliptic curve groups which ensure shorter keys. In the third part of our contribution, we propose secure methods to outsource the heavy operations in FIBE and KP-ABE schemes (i.e. scalar multiplication by a curve point, exponentiation, and pairing) such that IoT devices can cope with the complexity.

KDM Security IBE Based on LWE beyond Affine Functions

Key-dependent message (KDM) security identity-based encryption (IBE) schemes aim to solve the security risks caused by the dependency between plaintext and secret keys in traditional IBE schemes. However, current KDM-IBE schemes are only secure with respect to affine functions, which limits their security level when a message is derived from the evaluation of a polynomial function using the secret key. To address this issue, in this study, we propose a novel approach to construct a KDM-IBE scheme with respect to polynomial or even arbitrary functions that achieves maximum security based on the learning with errors (LWE) assumption. Our approach overcomes two major technical barriers to constructing KDM-IBE schemes with respect to polynomial functions. Compared to existing KDM-IBE schemes, our proposed scheme ensures the secrecy of the key-related plaintext, even when it is obtained using arbitrary functions, not just affine functions. Thus, our approach provides a more robust solution to the security risks inherent in traditional IBE schemes.

A computer-aided feature-based encryption model with concealed access structure for medical Internet of Things

One of the Internet of Things (IoT) security issues is the secure sharing and granular management of data access. This study recommends a feature-based encryption scheme with a hidden access structure for medical IoT data security. While establishing fine-grained access control of ciphertext data, the system can guarantee clinical client data privacy. First, it is recommended to convert identity-based encryption (IBE) into a feature-based encryption model (FBEM) using a universal conversion technique that supports multi-valued attributes and gates. IBE characteristics could be inherited by the converted FBEM. The conversion method is then used to change the receiver anonymous IBE scheme into the FBEM scheme with concealed access structure. The FBEM model is then used to construct the IoT scenario for the smart medical application. Theoretical analysis and experimental findings reveal that the suggested system provides advantages over prominent systems regarding computing efficiency, storage load, and security when the access structure is disguised.

Anonymous Homomorphic IBE with Application to Anonymous Aggregation

All anonymous identity-based encryption (IBE) schemes that are group homomorphic (to the best of our knowledge) require knowledge of the identity to compute the homomorphic operation. This paper is motivated by this open problem, namely to construct an anonymous group-homomorphic IBE scheme that does not sacrifice anonymity to perform homomorphic operations. Note that even when strong assumptions, such as indistinguishability obfuscation (iO), are permitted, no schemes are known. We succeed in solving this open problem by assuming iO and the hardness of the DBDH problem over rings (specifically, ZN2 for RSA modulus N). We then use the existence of such a scheme to construct an IBE scheme with re-randomizable anonymous encryption keys, which we prove to be IND-ID-RCCA secure. Finally, we use our results to construct identity-based anonymous aggregation protocols.

Improving User Privacy in Identity-Based Encryption Environments

The promise of identity-based systems is that they maintain the functionality of public key cryptography while eliminating the need for public key certificates. The first efficient identity-based encryption (IBE) scheme was proposed by Boneh and Franklin in 2001; variations have been proposed by many researchers since then. However, a common drawback is the requirement for a private key generator (PKG) that uses its own master private key to compute private keys for end users. Thus, the PKG can potentially decrypt all ciphertext in the environment (regardless of who the intended recipient is), which can have undesirable privacy implications. This has led to limited adoption and deployment of IBE technology. There have been numerous proposals to address this situation (which are often characterized as methods to reduce trust in the PKG). These typically involve threshold mechanisms or separation-of-duty architectures, but unfortunately often rely on non-collusion assumptions that cannot be guaranteed in real-world settings. This paper proposes a separation architecture that instantiates several intermediate CAs (ICAs), rather than one (as in previous work). We employ digital credentials (containing a specially-designed attribute based on bilinear maps) as the blind tokens issued by the ICAs, which allows a user to easily obtain multiple layers of pseudonymization prior to interacting with the PKG. As a result, our proposed architecture does not rely on unrealistic non-collusion assumptions and allows a user to reduce the probability of a privacy breach to an arbitrarily small value.

Continuous Leakage-resilient and Hierarchical Identity-based Online/Offline Encryption

<p>By dividing encryption as online and offline stages, the online/offline encryption schemes are very suitable to lightweight equipment. For the offline stage, high-performance equipment is used for complex preprocessing calculation, and the online stage the lightweight devices only make some simple calculations. In addition, side channel attacks can disclose some secret information of the cryptosystem, which leads to the destruction of the security of the cryptography schemes. Most of the online/offline identity-based encryption schemes cannot resist side channel attacks. The paper proposes a concrete hierarchical identity-based and online/offline encryption scheme that can resist continuous leakage of secret key. By the dual system encryption technology, we prove that the given scheme is fully secure. Through key updation technology, our proposed scheme resists continual leakage of private key. The relative leakage rate of the private key can reach 1/3. In addition, the presented scheme has the hierarchical function which effectively solves the problem of heavy load in a single key generation center. The given scheme is suitable for applications in distributed environment.</p> <p> </p>

Dual-Server Identity-Based Encryption with Authorized Equality Test for IoT Data in Clouds

The massive amounts of data collected by Internet of things (IoT) devices can be stored in clouds to solve the problem of the low storage capacity of IoT terminals. However, the privacy and security of outsourced IoT data may be compromised on the cloud side. Traditional cryptographic technologies can protect data privacy but require the user to retrieve the data for decryption and further processing, which would bring vast amounts of bandwidth and computation burden to users. This paper proposes a dual-server identity-based encryption scheme supporting authorized ciphertext equality test (DS-IBE-AET), where two noncolluding servers with authorizations from users can collaboratively carry out an equality test on outsourced IoT ciphertexts without decrypting the data. DS-IBE-AET can resist offline keyword guessing attacks confronted by existing encryption schemes with equality test in the single server model. Security analysis demonstrates that the proposed DS-IBE-AET scheme offers unforgeability for private keys of users and servers and confidentiality protection for outsourced IoT data and authentication tokens. The performance analysis indicates the practicality of our DS-IBE-AET construction for securing outsourced IoT data in clouds.

Reinforced securing of data leakage in Mobile Ad hoc Network (MANET) by hybrid mechanism of identity based encryption (IBE)

In Mobile Ad hoc Network (MANET), private data leakage that involves user’s private keys may become a threat to the computing systems security. It is essential that usual requirement of traditional cryptographic patterns or mechanisms have been performed for enduring several leakage attacks. However, the attacker can track and crack the cryptographic security due to the performance of continuous leakage attacks, which assist in introducing leakage resilience cryptography. But, still there are certain issues such as data loss, data failure system, data affecting and system break that are not yet resolved. As a result, various bounded-leakage models have been created for Identity Based Encryption (IBE) constructions that fail to fulfill their stated security under continuous-leakage assaults. This paper has introduced a hybrid mechanism of security to resolve the above listed issues by focusing in avoiding continuous leakage resilient through modified IBE schemes using Adaptive Chosen Cipher-text Attacks (ACCA) with Elliptical Curve Digital Signature Algorithm (ECDSA).

IBE-Signal: Reshaping Signal into a MITM-Attack-Resistant Protocol

The Signal Protocol is one of the most popular privacy protocols today for protecting Internet chats and supports end-to-end encryption. Nevertheless, despite its many advantages, the Signal Protocol is not resistant to Man-In-The-Middle (MITM) attacks because a malicious server can distribute the forged identity-based public keys during the user registration phase. To address this problem, we proposed the IBE-Signal scheme that replaced the Extended Triple Diffie–Hellman (X3DH) key agreement protocol with enhanced Identity-Based Encryption (IBE). Specifically, the adoption of verifiable parameter initialization ensures the authenticity of system parameters. At the same time, the Identity-Based Signature (IBS) enables our scheme to support mutual authentication. Moreover, we proposed a distributed key generation mechanism that served as a risk decentralization to mitigate IBE’s key escrow problem. Besides, the proposed revocable IBE scheme is used for the revocation problem. Notably, the IND-ID-CPA security of the IBE-Signal scheme is proven under the random oracle model. Compared with the existing schemes, our scheme provided new security features of mutual authentication, perfect forward secrecy, post-compromise security, and key revocation. Experiments showed that the computational overhead is lower than that of other schemes when the Cloud Privacy Centers (CPCs) number is less than 8.

A direct construction of continuous leakage-resilient (H)IBE scheme with CCA security from dual system encryption

Continuous leakage resilient semantically secure Identity-based Encryption (IBE) schemes created with dual system encryption technique were presented by Lewko et al. at TCC 2011 and Yuen et al. at Eurocrypt 2012, respectively. It has been a research challenge to achieve the security against chosen-ciphertext attacks (CCA). The previous attempts toward the CCA security rely on q-type assumptions, which are referred as non-static assumptions causing loose reduction in security proofs. In this paper, we provide a complete solution to the problem and show how to construct the continuous leakage-resilient IBE with weaker CCA security based on the dual system encryption technique, where the adversary is allowed to make continuous leakage queries. We are able to prove its security with static assumptions in the standard model. As a feature of our scheme, we allow leakage of multiple keys, i.e., leakage of the master secret key and the private key of user. Our scheme also enjoys better computational performance, since the round leakage parameter is independent of the plaintext space and has a constant size. Furthermore, our scheme can be easily extended to give the weaker CCA secure continuous leakage-resilient hierarchical identity-based encryption scheme with a short ciphertext length.

CLAP-PRE: Certificateless Autonomous Path Proxy Re-Encryption for Data Sharing in the Cloud

In e-health systems, patients encrypt their personal health data for privacy purposes and upload them to the cloud. There exists a need for sharing patient health data with doctors for healing purposes in one’s own preferred order. To achieve this fine-gained access control to delegation paths, some researchers have designed a new proxy re-encryption (PRE) scheme called autonomous path proxy re-encryption (AP-PRE), where the delegator can control the whole delegation path in a multi-hop delegation process. In this paper, we introduce a certificateless autonomous path proxy re-encryption (CLAP-PRE) using multilinear maps, which holds both the properties (i.e., certificateless, autonomous path) of certificateless encryption and autonomous path proxy re-encryption. In the proposed scheme, (a) each user has two public keys (user’s identity and traditional public key) with corresponding private keys, and (b) each ciphertext is first re-encrypted from a public key encryption (PKE) scheme to an identity-based encryption (IBE) scheme and then transformed in the IBE scheme. Our scheme is an IND-CPA secure CLAP-PRE scheme under the k-multilinear decisional Diffie–Hellman (k-MDDH) assumption in the random oracle model.

Identity-Based Encryption With Continuous Leakage-Resilient CCA Security From Static Complexity Assumption

Abstract Although a large number of provably secure cryptographic primitives have been proposed in the literature, many of these schemes might be broken in practice because of various leakage attacks. Therefore, the leakage resilience should be considered in designing these primitives. However, in identity-based cryptography, most of the existing leakage-resilient identity-based encryption (IBE) schemes suffer some limitations: they either resist the leakage attacks in the selective identity security model or achieve the chosen-ciphertext attack (CCA) security based on a non-static assumption. In this paper, an IBE scheme with adaptive leakage-resilient CCA security is proposed, and its security is rigorously proved in the random oracle model under a classic static complexity assumption, e.g. decisional bilinear Diffie–Hellman assumption. In our construction, all elements of ciphertext are randomly distributed in the adversary’s view. Hence, the adversary cannot obtain any useful information of the user’s private key from the given ciphertexts. Moreover, a unique property of our construction is that the leakage parameter is independent of the plaintext space, which contributes a better leakage rate.

Receiver Selective Opening Chosen Ciphertext Secure Identity-Based Encryption

In the situation where there are one sender and multiple receivers, a receiver selective opening (RSO) attack for an identity-based encryption (IBE) scheme considers adversaries that can corrupt some of the receivers and get their user secret keys and plaintexts. Security against RSO attacks for an IBE scheme ensures confidentiality of ciphertexts of uncorrupted receivers. In this paper, we formalize a definition of RSO security against chosen ciphertext attacks (RSO-CCA security) for IBE and propose the first RSO-CCA secure IBE schemes. More specifically, we construct an RSO-CCA secure IBE scheme based on an IND-ID-CPA secure IBE scheme and a non-interactive zero-knowledge proof system with unbounded simulation soundness and multi-theorem zero-knowledge. Through our generic construction, we obtain the first pairing-based and lattice-based RSO-CCA secure IBE schemes.

Quantum Identity-Based Encryption from the Learning with Errors Problem

To prevent eavesdropping and tampering, network security protocols take advantage of asymmetric ciphers to establish session-specific shared keys with which further communication is encrypted using symmetric ciphers. Commonly used asymmetric algorithms include public key encryption, key exchange, and identity-based encryption (IBE). However, network security protocols based on classic identity-based encryption schemes do not have perfect forward secrecy. To solve this problem, we construct the first quantum IBE (QIBE) scheme based on the learning with errors (LWE) problem, which is also the first cryptographic scheme that applies the LWE problem to quantum encryption. We prove that our scheme is fully secure under the random oracle model and highlight the following advantages: (1) Network security protocols with our QIBE scheme provide perfect forward secrecy. The ciphertext is transmitted in the form of a quantum state unknown to the adversary and cannot be copied and stored. Thus, in network security protocols based on QIBE construction, the adversary does not have any previous quantum ciphertext to decrypt for obtaining the previous session key, even if the private identity key is threatened. (2) Classic key generation centre (KGC) systems can still be used in the QIBE scheme to generate and distribute private identity keys, reducing the cost when implementing this scheme. The classic KGC systems can be used because the master public and secret keys of our scheme are both in the form of classic bits. Finally, we present quantum circuits to implement this QIBE scheme and analyse its required quantum resources for given numbers of qubits, Hadamard gates, phase gates, T gates, and CNOT (controlled-NOT) gates. One of our main findings is that the quantum resources required by our scheme increase linearly with the number of plaintext bits to be encrypted.