IBE Scheme Research Articles

Verifiable delay functions and delay encryptions from hyperelliptic curves

Verifiable delay functions (VDFs) and delay encryptions (DEs) are two important primitives in decentralized systems, while existing constructions are mainly based on time-lock puzzles. A disparate framework has been established by applying isogenies and pairings on elliptic curves. Following this line, we first employ Richelot isogenies and non-degenerate pairings from hyperelliptic curves for a new verifiable delay function, such that no auxiliary proof and interaction are needed for the verification. Then, we demonstrate that our scheme satisfies all security requirements, in particular, our VDF can resist several attacks, including the latest attacks for SIDH. Besides, resorting to the same techniques, a secure delay encryption from hyperelliptic curves is constructed by modifying Boneh and Frankiln’s IBE scheme, which shares the identical setup with our VDF scheme. As far as we know, these schemes are the first cryptographic applications from high-genus isogenies apart from basic protocols, i.e., hash functions and key exchange protocols.

Efficient Multi-Identity Full Homomorphic Encryption Scheme on Lattice

Aiming at the problem that the fully homomorphic encryption scheme based on single identity cannot satisfy the homomorphic operation of ciphertext under different identities, as well as the inefficiency of trapdoor function and the complexity of sampling algorithm, an improved lattice MIBFHE scheme was proposed. Firstly, we combined MP12 trapdoor function with dual LWE algorithm to construct a new IBE scheme under the standard model, and prove that the scheme is IND-sID-CPA security under the selective identity. Secondly, we used the eigenvector method to eliminate the evaluation key, and transform the above efficient IBE scheme into a single identity IBFHE scheme to satisfy the homomorphic operation. Finally, we improved the ciphertext extension method of CM15 and constructed a new Link-mask system that supports the transformation of IBFHE scheme under the standard model, and then, converted the above IBFHE scheme into MIBFHE scheme based on this system. The comparative analysis results showed that the efficiency of this scheme is improved compared with similar schemes in the trapdoor generation and preimage sampling, and the dimension of lattice and ciphertext size are significantly shortened.

IIBES: a proposed framework to improve the identity-based encryption system for securing federated learning

Purpose In the field of cryptography, authentication, secrecy and identification can be accomplished by use of secret keys for any computer-based system. The need to acquire certificates endorsed through CA to substantiate users for the barter of encoded communications is one of the most significant constraints for the extensive recognition of PKC, as the technique takes too much time and susceptible to error. PKC’s certificate and key management operating costs are reduced with IBC. IBE is a crucial primeval in IBC. The thought behind presenting the IBE scheme was to diminish the complexity of certificate and key management, but it also gives rise to key escrow and key revocation problem, which provides access to unauthorised users for the encrypted information. Design/methodology/approach This paper aims to compare the result of IIBES with the existing system and to provide security analysis for the same and the proposed system can be used for the security in federated learning. Findings Furthermore, it can be implemented using other encryption/decryption algorithms like elliptic curve cryptography (ECC) to compare the execution efficiency. The proposed system can be used for the security in federated learning. Originality/value As a result, a novel enhanced IBE scheme: IIBES is suggested and implemented in JAVA programming language using RSA algorithm, which eradicates the key escrow problem through eliminating the need for a KGC and key revocation problem by sing sub-KGC (SKGC) and a shared secret with nonce. IIBES also provides authentication through IBS as well as it can be used for securing the data in federated learning.

A formal security proof of generic construction of anonymous IBE from PEKS

Abdalla et al.[1, 2] proposed a transform of an anonymous IBE (A-IBE) scheme to a PEKS(Publickey encryption with keyword search) scheme. Boneh et al. proposed a transform of a PEKS schemeto an A-IBE scheme for only one-bit message. Rhee et al.[3] proposed a transform for constructingan A-IBE scheme for polynomially many-bit message by using a PEKS scheme. They firstly defineda multiple PEKS (mPEKS) scheme and showed that a mPEKS scheme can be constructed from aPEKS scheme. In this paper, we formally prove that if a PEKS scheme is confidential, so is theresulting mPEKS scheme. We then provide a transform from a mPEKS scheme to an A-IBE schemefor a polynomially many-bit message.

Adaptively secure revocable hierarchical IBE from k-linear assumption

Revocable identity-based encryption (RIBE) is an extension of IBE with an efficient key revocation mechanism. Revocable hierarchical IBE (RHIBE) is its further extension with key delegation functionality. Although there are various adaptively secure pairing-based RIBE schemes, all known hierarchical analogues only satisfy selective security. In addition, the currently known most efficient adaptively secure RIBE and selectively secure RHIBE schemes rely on non-standard assumptions, which are referred to as the augmented DDH assumption and q-type assumptions, respectively. In this paper, we propose a simple but effective design methodology for RHIBE schemes. We provide a generic design framework for RHIBE based on an HIBE scheme with a few properties. Fortunately, several state-of-the-art pairing-based HIBE schemes have the properties. In addition, our construction preserves the sizes of master public keys, ciphertexts, and decryption keys, as well as the complexity assumptions of the underlying HIBE scheme. Thus, we obtain the first RHIBE schemes with adaptive security under the standard k-linear assumption. We prove adaptive security by developing a new proof technique for RHIBE. Due to the compactness-preserving construction, the proposed R(H)IBE schemes have similar efficiencies to the most efficient existing schemes.

Identity Based Broadcast Encryption Scheme with Shorter Decryption Keys for Open Networks

In Broadcast Encryption schemes, a sender can broadcast the encrypted message securely in a threatening network to a set of legitimate system users only. In IBE scheme any sender can encrypt the desired message using his/her identity without attaining the public key certificate. Here, we have presented an efficient ID-based broadcast encryption scheme (IBBE) for open networks. In this scheme, desired messages can be broadcasted to any subset of the users by any sender but only authorized receivers are capable in retrieving the encrypted messages. This scheme has shorter decryption keys in comparison with other primitive of IBBE scheme for open networks. Moreover, the proposed scheme intends to achieve the lower cost for computation as well as transmission in comparison to earlier existing IBBE schemes.

Fully secure wicked identity-based encryption resilient to continual auxiliary- inputs leakage

To allow more general key derivation patterns, the concept of wicked identity-based encryption (wicked IBE) was introduced. It is an extension of hierarchical identity based encryption (HIBE). Recently, research on leakage-resilient wicked IBE has attracted much attention for its consideration on the problem of key leakage in system. However, the existing works implement leakage resistance under the bounded leakage model and fail to capture general form of leakage attacks. Through designing the generation of the master secret key and the user secret key reasonably, a wicked IBE scheme resilient to continual auxiliary-inputs leakage is proposed in this paper. The leakage of our scheme is not only from the user secret key, but also from the master secret key. We show the scheme is proven fully secure in the standard model based on the subgroup decision assumption in composite-order bilinear groups and the Goldreich-Levin theorem in Galois field. To achieve this goal, the dual system encryption technology is exploited in the security proof. Compared with existing leakage-resilient wicked IBE, our scheme has a better performance in leakage resilience and security.

Lattice-based revocable (hierarchical) IBE with decryption key exposure resistance

Revocable identity-based encryption (RIBE) is an extension of IBE that supports a key revocation mechanism, which is an indispensable feature for practical cryptographic schemes. Due to this extra feature, RIBE is often required to satisfy a strong security notion unique to the revocation setting called decryption key exposure resistance (DKER). Additionally, hierarchal IBE (HIBE) is another orthogonal extension of IBE that supports key delegation functionalities allowing for scalable deployments of cryptographic schemes. So far, R(H)IBE constructions with DKER are only known from bilinear maps, where all constructions rely heavily on the so-called key re-randomization property to achieve the DKER and/or hierarchal feature. Since lattice-based schemes seem to be inherently ill-fit with the key re-randomization property, no construction of lattice-based R(H)IBE schemes with DKER are known.In this paper, we propose the first lattice-based RHIBE scheme with DKER without relying on the key re-randomization property, departing from all the previously known methods. We start our work by providing a generic construction of RIBE schemes with DKER, which uses as building blocks any two-level standard HIBE scheme and (weak) RIBE scheme without DKER. Based on previous lattice-based RIBE constructions without DKER, our result implies the first lattice-based RIBE scheme with DKER. Then, building on top of our generic construction, we construct the first lattice-based RHIBE scheme with DKER, by further exploiting the algebraic structure of lattices. To this end, we prepare a new tool called the level conversion keys, which enables us to achieve the hierarchal feature without relying on the key re-randomization property. In this full version, we give the formal proofs of our proposed schemes.

Identity‐based encryption resilient to continuous key leakage

Leakage of private information has become a threat to the security of computing systems. It has become a common security requirement that a cryptography scheme should withstand various leakage attacks, even the continuous leakage attacks. However, in the current constructions on the (continuous) leakage-resilient identity-based encryption (CLR-IBE) scheme, the leakage parameter is a fixed value. Aiming to solve these problems, in this study, the authors show how to construct the CLR-IBE scheme, and the adaptive chosen-ciphertext attacks security of proposed construction can be proved in the standard model. To further improve the practicability of CLR-IBE scheme, they design an improved IBE scheme with continuous leakage amplified property, and the leakage parameter has an arbitrary length.

Controlled secure social cloud data sharing based on a novel identity based proxy re-encryption plus scheme

Currently we are witnessing a rapid integration of social networks and cloud computing, especially on storing social media contents on cloud storage due to its cheap management and easy accessing at any time and from any place. However, how to securely store and share social media contents such as pictures/videos among social groups is still a very challenging problem. In this paper, we try to tackle this problem by using a new cryptographic primitive: identity based proxy re-encryption plus (IBPRE +), which is a variant of proxy re-encryption (PRE). In PRE, by using re-encryption keys, a ciphertext computed for Alice can be transferred to a new one for Bob. Recently, the concept of PRE plus (PRE+) was introduced by Wang et al. In PRE+, all the algorithms are almost the same as traditional PRE, except the re-encryption keys are generated by the encrypter instead of the delegator. The message-level based fine-grained delegation property and the weak non-transferable property can be easily achieved by PRE +, while traditional PRE cannot achieve them. Based on the 3-linear map, we first propose a new IBE scheme and a new IBPRE+ scheme, we prove the security of these schemes and give the properties and performance analysis of the new IBPRE+ scheme. Finally, we propose a new framework based on this new primitive for secure cloud social data sharing.

A Generic Construction of Integrated Secure-Channel Free PEKS and PKE and its Application to EMRs in Cloud Storage.

To provide a search functionality for encrypted data, public key encryption with keyword search (PEKS) has been widely recognized. In actual usage, a PEKS scheme should be employed with a PKE scheme since PEKS itself does not support the decryption of data. Since a naive composition of a PEKS ciphertext and a PKE ciphertext does not provide CCA security, several attempts have been made to integrate PEKS and PKE in a joint CCA manner (PEKS/PKE for short). In this paper, we further extend these works by integrating secure-channel free PEKS (SCF-PEKS) and PKE, which we call SCF-PEKS/PKE, where no secure channel is required to send trapdoors. We give a formal security definition of SCF-PEKS/PKE in a joint CCA manner, and propose a generic construction of SCF-PEKS/PKE based on anonymous identity-based encryption, tag-based encryption, and one-time signature. We also strengthen the current consistency definition according to the secure-channel free property, and show that our construction is strongly consistent if the underlying IBE provides unrestricted strong collision-freeness which is defined in this paper. We also show that such an IBE scheme can be constructed by employing the Abdalla et al. transformations (TCC 2010/J. Cryptology 2018). Finally, as an application of SCF-PEKS/PKE, we strengthen the security of encrypted Electronic Medical Record (EMR) system proposed by Guo and Yau (J. Medical Sys. 2015).

Implementation of Algorithms for Identity Based Encryption and Decryption

Identity-based cryptosystems were introduced to overcome one of the main problems in public key encryption, the generation of public and private keys. In the identity-based cryptosystem, an identifier such as an e-mail address of a user can be used to generate public and private keys by a trusted third party. The trusted third party uses a system-wide master secret to provide private keys to a user. Identity-based cryptosystems can be constructed using the idea of pairings. This article discusses four different identity-based cryptosystems: the Boneh-Franklin scheme, the Cock's scheme, the Authenticated IBE scheme and the Hierarchical IBE scheme. This article also discusses the security notions considered for the identity-based cryptosystem. The security notions considered are: one-wayness, indistinguishability, semantic security and non-malleability. An architecture consisting of a public parameter server and private key generator for the implementation of the identity-based cryptosystems is also discussed.

Efficient batch identity‐based fully homomorphic encryption scheme in the standard model

Identity-based fully homomorphic encryption (IBFHE) provided a fundamental solution to the problem of huge public key size that exposed in fully homomorphic encryption (FHE) schemes, thus it is significant to make FHE become more practical. In recent years, the construction of IBFHE schemes were mainly based on lattices due to their conjectured resistance against quantum cryptanalysis, however, which makes these cryptosystems further unpractical. The main reason is the trapdoor function on which the scheme was based is rather complex for practical and the ciphertext size is too large. In this study, the authors propose an efficient batch IBFHE scheme, which can be proven secure from the standard LWE assumption in the standard model. The first contribution of this work is that the authors construct an efficient batch version of MP12 preimage sampling algorithm, which can efficiently generate identity keys for multi-bit IBE schemes. Based on that, the authors construct an asymptotically-faster multi-bit IBE scheme as the second contribution. The third contribution is that the authors transform the multi-bit IBE scheme to batch IBFHE scheme which supports to encrypt any message in Z q n . Compared with the similar schemes, the authors show their schemes are essentially improved.

An IBE Scheme with Verifiable Outsourced Key Generation Based on a Single Server

ABSTRACTIt is well known that private key generation is a computing bottleneck in an identity-based encryption scheme when a large number of users exist. Outsourcing computation can greatly reduce the users’ computational cost, but the existing schemes are all based on two servers, which are not feasible in the real cloud environment. In this paper, we first propose a scheme where the PKG outsources the task of private key generation to a single server, and the results can be verified effectively. Moreover, PKG only needs to execute 1 modular exponentiation, so it is more efficient when compared with previous schemes. Meanwhile, we prove the indistinguishability of the ciphertext and verifiability of the outsourcing results in the security model. Finally, the proposed algorithm is realized in a simulation environment. Theoretical analysis and experimental results show that total computing time of PKG and the server in the outsourced algorithm is far less than that of direct computation.

Continuous leakage–resilient IBE in cloud computing

SummaryCloud computing is an efficient tool in which cloud storage shares plenty of encrypted data with other data owners. In existing cloud computing scenarios, it may suffer from some new attacks like side channel attacks. Therefore, we are eager to introduce a new cryptographic scheme that can resist these new attacks. In this work, we exploit a new technique to build leakage‐resilient identity‐based encryption and use the stronger existing partial leakage model, such as continual leakage model. More specifically, our proposal is based on the underlying decisional bilinear Diffie‐Hellman assumption, but proven adaptively secure against adaptive chosen ciphertext attack in the standard model. Above all, a continuous leakage–resilient IBE scheme with adaptive security meets cloud computing with stronger security.

Revocable hierarchical identity-based encryption with shorter private keys and update keys

Revocable hierarchical identity-based encryption (RHIBE) is an extension of HIBE that supports the revocation of user’s private keys to manage the dynamic credentials of users in a system. Many different RHIBE schemes were proposed previously, but they are not efficient in terms of the private key size and the update key size since the depth of a hierarchical identity is included as a multiplicative factor. In this paper, we propose efficient RHIBE schemes with shorter private keys and update keys and small public parameters by removing this multiplicative factor. To achieve our goals, we first present a new HIBE scheme with the different generation of private keys such that a private key can be simply derived from a short intermediate private key. Next, we show that two efficient RHIBE schemes can be built by combining our HIBE scheme, an IBE scheme, and a tree based broadcast encryption scheme in a modular way.

Multimodal biometric Identity Based Encryption

In this paper, we describe the first generic construction for multimodal biometric Identity Based Encryption considering two distance measures at the same time. Current protocols for fuzzy/biometric IBE are designed either for set overlap or Euclidean distance within unimodal biometrics. However, the similarity measures for biometric templates can be quite different from those considered in theoretical works. For instance, a fingerprint template usually consists of a set of minutiae, and two templates are considered as similar if more than a certain number of minutiae in one template are near distinct minutiae in the other. In this case, the similarity measure has to consider both Euclidean distance and set difference at the same time. Similarly, multimodal systems that are designed to address the limitations of unimodal systems may involve two different traits requiring different distance measures for each modality.In order to have high recognition rate and thus increased possibility of decryption even in case of white noise (slight perturbation of biometric features), our generic construction is based on two different biometric IBE systems encoding the same message. This way, employment of both distance measures is possible using multiple matchers within multimodal setting and a failure on the decryption of a message encrypted using the first biometric representation, can be compensated with an attempt on the second part of the ciphertext encrypting the same message but using a different representation of the same receiver. Specifically, we combine a fuzzy IBE-type scheme and the recently introduced Distance Based Encryption (DBE) scheme with minimum overhead in terms of public parameters, ciphertext and private key size. For this purpose, we describe an efficient biometric IBE scheme denoted as ordFIBE, which is restricted for biometrics that can be represented as an ordered/grouped set of features. We study the security of ordFIBE both in random oracle model (ROM) and for small universe of attributes in standard model. In ROM, its efficiency is further improved by employing online/offline encryption technique. Next, we instantiate the new construction by combining ordFIBE and the DBE scheme of Guo et al. (2014), which shares the same setup phase, in particular, common public parameters. Finally, we describe a new scheme for set difference metric that partially solves an open problem introduced in Katz et al. (2008).

Robust Encryption

We provide a provable-security treatment of "robust" encryption. Robustness means it is hard to produce a ciphertext that is valid for two different users. Robustness makes explicit a property that has been implicitly assumed in the past. We argue that it is an essential conjunct of anonymous encryption. We show that natural anonymity-preserving ways to achieve it, such as adding recipient identification information before encrypting, fail. We provide transforms that do achieve it, efficiently and provably. We assess the robustness of specific encryption schemes in the literature, providing simple patches for some that lack the property. We explain that robustness of the underlying anonymous IBE scheme is essential for public-key encryption with keyword search (PEKS) to be consistent (meaning, not have false positives), and our work provides the first generic conversions of anonymous IBE schemes to consistent (and secure) PEKS schemes. Overall, our work enables safer and simpler use of encryption.

How to Protect ADS-B: Confidentiality Framework and Efficient Realization Based on Staged Identity-Based Encryption

Automatic Dependent Surveillance-Broadcast (ADS-B) is one of the key technologies for future “e-Enabled” aircrafts. ADS-B uses avionics in the e-Enabled aircrafts to broadcast essential flight data such as call sign, altitude, heading, and other extra positioning information. On the one hand, ADS-B brings significant benefits to the aviation industry, but, on the other hand, it could pose security concerns as channels between ground controllers and aircrafts for the ADS-B communication are not secured, and ADS-B messages could be captured by random individuals who own ADS-B receivers. In certain situations, ADS-B messages contain sensitive information, particularly when communications occur among mission-critical civil airplanes. These messages need to be protected from any interruption and eavesdropping. The challenge here is to construct an encryption scheme that is fast enough for very frequent encryption and that is flexible enough for effective key management. In this paper, we propose a Staged Identity-Based Encryption (SIBE) scheme, which modifies Boneh and Franklin's original IBE scheme to address those challenges, that is, to construct an efficient and functional encryption scheme for ADS-B system. Based on the proposed SIBE scheme, we provide a confidentiality framework for future e-Enabled aircraft with ADS-B capability.

New Security Proof for the Boneh-Boyen IBE: Tight Reduction in Unbounded Multi-Challenge Security

Identity-based encryption IBE is an advanced form of public key encryption and one of the most important cryptographic primitives. Of the many constructions of IBE schemes, the one proposed by Boneh and Boyen in Eurocrypt 2004 is quite important from both practical and theoretical points of view. The scheme was standardized as IEEE P1363.3 and is the basis for many subsequent constructions. In this paper, we investigate its multi-challenge security, which means that an adversary is allowed to query challenge ciphertexts multiple times rather than only once. Since single-challenge security implies multi-challenge security, and since Boneh and Boyen provided a security proof for the scheme in the single-challenge setting, the scheme is also secure in the multi-challenge setting. However, this reduction results in a large security loss. Instead, we give tight security reduction for the scheme in the multi-challenge setting. Our reduction is tight even if the number of challenge queries is not fixed in advance that is, the queries are unbounded. Unfortunately, we are only able to prove the security in a selective setting and rely on a non-standard parameterized assumption. Nevertheless, we believe that our new security proof is of interest and provides new insight into the security of the Boneh-Boyen IBE scheme.