Some Remarks on Cocks'Identity-Based Encryption Scheme

The theory of quadratic residues plays an important role in cryptography.In 2001,Cocks developed an identity-based encryption(IBE)scheme based on quadratic residues,resolving Shamir’s 17-year-old open problem.However,a notable drawback of Cocks’scheme is the significant expansion of the ciphertext,and some of its limitations have been addressed in subsequent research.Recently,Cotan and Teşeleanu highlighted that previous studies on Cocks’scheme relied on a trial-and-error method based on Jacobi symbols to generate the necessary parameters for the encryption process.They enhanced the encryption speed of Cocks’scheme by eliminating this trialand-error method.Based on security analysis,this study concludes that the security of Cotan-Teşeleanu’s proposal cannot be directly derived from the security of the original Cocks’scheme.Furthermore,by adopting the Cotan-Teşeleanu method and introducing an additional variable as a public element,this study develops a similar enhancement scheme that not only accelerates the encryption speed but also provides security equivalent to the original Cocks’scheme.

Construction and Implementation of a Privacy-Preserving Identity-Based Encryption Architecture

A recent proposal by Adams integrates the digital credentials (DC) technology of Brands with the identity-based encryption (IBE) technology of Boneh and Franklin to create an IBE scheme that demonstrably enhances privacy for users. We refer to this scheme as a privacy-preserving identity-based encryption (PP-IBE) construction. In this paper, we discuss the concrete implementation considerations for PP-IBE and provide a detailed instantiation (based on q-torsion groups in supersingular elliptic curves) that may be useful both for proof-of-concept purposes and for pedagogical purposes.

Fully Secure Identity-based Broadcast Encryption in the Subgroups

In this paper,we show how to use the dual techniques in the subgroups to give a secure identity-based broadcast encryption(IBBE) scheme with constant-size ciphertexts. Our scheme achieves the full security(adaptive security) under three static(i.e. non q-based) assumptions. It is worth noting that only recently Waters gives a short ciphertext broadcast encryption system that is even adaptively secure under the simple assumptions. One feature of our methodology is that it is relatively simple to leverage our techniques to get adaptive security.

An Efficient Identity-Based Homomorphic Broadcast Encryption

Broadcast encryption (BE) allows a sender to broadcast its message to a set of receivers in a single ciphertext. However, in broadcast encryption scheme, ciphertext length is always related to the size of the receiver set. Thus, how to improve the communication of broadcast encryption is a big issue. In this paper, we proposed an identity-based homomorphic broadcast encryption scheme which supports an external entity to directly calculate ciphertexts and get a new ciphertext which is the corresponding result of the operation on plaintexts without decrypting them. The correctness and security proofs of our scheme were formally proved. Finally, we implemented our scheme in a simulation environment and the experiment results showed that our scheme is efficient for practical applications.

OBLIVIOUS TRANSFER WITH ACCESS CONTROL AND IDENTITY-BASED ENCRYPTION WITH ANONYMOUS KEY ISSUING

In ACM'CCS 2009,Camenisch,et al.proposed the Oblivious Transfer with Access Control(AC-OT) in which each item is associated with an attribute set and can only be available,on request,to the users who have all the attributes in the associated set.Namely,AC-OT achieves access control policy for conjunction of attributes.Essentially,the functionality of AC-OT is equivalent to the sim-plified version that we call AC-OT-SV:for each item,one attribute is associated with it,and it is requested that only the users who possess the associated attribute can obtain the item by queries.On one hand,AC-OT-SV is a special case of AC-OT when there is just one associated attribute with each item.On the other hand,any AC-OT can be realized by an AC-OT-SV.In this paper,we first present a concrete AC-OT-SV protocol which is proved to be secure in the model defined by Camenisch,et al..Then from the protocol,interestingly,a concrete Identity-Based Encryption(IBE) with Anonymous Key Issuing(AKI) is given which is just a direct application to AC-OT-SV.By comparison,we show that the AKI protocol we present is more efficient in communications than that proposed by Chow.

Security Analysis of a Privacy-Preserving Identity-Based Encryption Architecture

Identity-Based Encryption (IBE) has seen limited adoption, largely due to the absolute trust that must be placed in the private key generator (PKG)—an authority that computes the private keys for all the users in the environment. Several constructions have been proposed to reduce the trust required in the PKG (and thus preserve the privacy of users), but these have generally relied on unrealistic assumptions regarding non-collusion between various entities in the system. Unfortunately, these constructions have not significantly improved IBE adoption rates in real-world environments. In this paper, we present a construction that reduces trust in the PKG without unrealistic non-collusion assumptions. We achieve this by incorporating a novel combination of digital credential technology and bilinear maps, and making use of multiple randomly-chosen entities to complete certain tasks. The main result and primary contribution of this paper are a thorough security analysis of this proposed construction, examining the various entity types, attacker models, and collusion opportunities in this environment. We show that this construction can prevent, or at least mitigate, all considered attacks. We conclude that our construction appears to be effective in preserving user privacy and we hope that this construction and its security analysis will encourage greater use of IBE in real-world environments.

Identity-Based Steganography in Spatial Domain

This paper proposed an identity-based steganographic scheme, where a receiver with certain authority can recover the secret message ready for him, but cannot detect the existence of other secret messages. The proposed scheme created several separate covert communication channels tagged by the Fuzzy Identity-Based Encryption (FIBE) in one grayscale image. Then each channel is used to embed one secret message by using any content-aware steganographic scheme. Receivers with different attributes can extract different messages corresponded. The Experiments illustrated the feasibility of this identity-based secret message extraction. Further, the proposed scheme presents high undetectability against steganalytic attack launched by receivers without corresponded attributes.

An Authenticated Identity-Based Key Establishment and Encryption Scheme for Wireless Sensor Networks

Security of wireless sensor networks has received considerable attention. It is a critical challenge to find out suitable encryption schemes for wireless sensor networks due to limitations of power, computation capability and storage resources of these networks. Many encryption schemes based on asymmetric and symmetric have been investigated. In this paper, we present an authenticated identity-based key encryption scheme for wireless sensor networks. We first review briefly about identity-based encryption and decryption, particularly, the Boneh-Franklin algorithms, then describe an authenticated identity-based key encryption scheme based on Boneh-Franklin algorithms, and finally show the integrity of our scheme and discuss its efficiency and security by comparing it with other asymmetric and symmetric encryption schemes.

New Constructions for Identity-Based Unidirectional Proxy Re-Encryption

We address the cryptographic topic of proxy re-encryption （PRE）, which is a special public-key cryptosystem. A PRE scheme allows a special entity, known as the proxy, to transform a message encrypted with the public key of a delegator （say Alice）, into a new ciphertext that is protected under the public key of a delegatee （say Bob）, and thus the same message can then be recovered with Bob＇s private key. In this paper, in the identity-based setting, we first investigate the relationship between so called mediated encryption and unidirectional PRE. We provide a general framework which converts any secure identity-based unidirectional PRE scheme into a secure identity-based mediated encryption scheme, and vice versa. Concerning the security for unidirectional PRE schemes, Ateniese et al. previously suggested an important property known as the master secret security, which requires that the coalition of the proxy and Bob cannot expose Alice＇s private key. In this paper, we extend the notion to the identity-based setting, and present an identity-based unidirectional PRE scheme, which not only is provably secure against the chosen eiphertext attack in the standard model but also achieves the master secret security at the same time.

Identity-based encryption with wildcards in the standard model

In this article, based on Chatterjee-Sarkar＇ hierarchical identity-based encryption （HIBE）, a novel identity-based encryption with wildcards （WIBE） scheme is proposed and is proven secure in the standard model （without random oracle）. The proposed scheme is proven to be secure assuming that the decisional Bilinear Diffie-Hellman （DBDH） problem is hard. Compared with the Wa-WIBE scheme that is secure in the standard model, our scheme has shorter common parameters and ciphertext length.

Dynamic Cluster Key Management Scheme on Wireless Sensor Networks

Wireless sensor networks are open architectures, so any potential threat can easily intercept, wiretap and counterfeit the information. Therefore, the safety of WSN is very important. Since any single key system cannot guarantee the security of the wireless sensor network for communications, this paper introduces a hierarchical key management scheme based on the different abilities of different sensor nodes in the clustered wireless sensor network. In this scheme, the nodes are distributed into several clusters, and a cluster head must be elected for each cluster. Private communication between cluster heads is realized through the encryption system based on the identity of each head while private communication between cluster nodes in a same cluster head is achieved through the random key preliminary distribution system. Considering the characteristics of WSN, we adopt dynamic means called dynamic cluster key management scheme to deal with master key, so master key will be updated according to the changed dynamic network topology. For cluster head node plays a pivotal role in this scheme, a trust manage-ment system should be introduced into the election of the cluster head which will exclude the malicious node from outside the cluster, thus improve the whole network security.

Identity-based Broadcast Encryption with Shorter Transmissions

This paper describes two identity-based broadcast encryption （IBBE） schemes for mobile ad hoc networks. The first scheme proposed achieves sub-linear size cipertexts and the second scheme achieves O（1）- size ciphertexts. Furthermore, when the public keys are transmitted, the two schemes have short transmissions and achieve O（1） user storage cost, which are important for a mobile ad hoc network. Finally, the proposed schemes are provable security under the decision generalized bilinear Diffi-Hellman （GBDH） assumption in the random oracles model.

Identity-based Encryption with Non-Interactive Opening

An identity-based encryption(IBE) was studied with non-interactively opening property that the plain text of a ciphertext can be revealed without affecting the security of the encryption system.Two kinds of non-interactive opening properties for IBE schemes were defined along with a concrete scheme in each case.

Updatable Identity-Based Hash Proof System Based on Lattices and Its Application to Leakage-Resilient Public-Key Encryption Schemes

Identity-based hash proof system is a basic and important primitive. Ittographic schemes and protocols that are secure against key-leakage attacks. In thisupdatable identity-based hash proof system, in which the related master secret keyis widely utilized to construct cryp-paper, we introduce the concept ofand the identity secret key can beupdated securely. Then, we instantiate this primitive based on lattices in the standard model. Moreover, we introduce anapplication of this new primitive by giving a generic construction of leakage-resilient public-key encryption schemes withanonymity. This construction can be considered as the integration of the bounded-retrieval model and the continual leakagemodel. Compared with the existing leakage-resilient schemes, our construction not only is more efficient but also can resistmuch more key leakage.

Reflections on the security proofs of Boneh-Franklin identity-based encryption scheme

In this paper, we first review the existing proofs of the Boneh-Franklin identity-based encryption scheme (BF-IBE for short), and show how to admit a new proof by slightly modifying the specifications of the hash functions of the original BF-IBE. Compared with prior proofs, our new proof provides a tighter security reduction and minimizes the use of random oracles, thus indicates BF-IBE has better provable security with our new choices of hash functions. The techniques developed in our proof can also be applied to improving security analysis of some other IBE schemes. As an independent technical contribution, we also give a rigorous proof of the Fujisaki-Okamoto (FO) transformation in the case of CPA-to-CCA, which demonstrates the efficiency of the FO-transformation (CPA-to-CCA), in terms of the tightness of security reduction, has long been underestimated. This result can remarkably benefit the security proofs of encryption schemes using the FO-transformation for CPA-to-CCA enhancement.

Practical continuous leakage-resilient CCA secure identity-based encryption

Leakage of private information including private keys of user has become a threat to the security of computing systems.It has become a common security requirement that a cryptographic scheme should withstand various leakage attacks.In the real life,an adversary can break the security of cryptography primitive by performing continuous leakage attacks.Although,some research on the leakage-resilient cryptography had been made,there are still some remaining issued in previous attempts.The identity-based encryption(IBE)constructions were designed in the bounded-leakage model,and might not be able to meet their claimed security under the continuous-leakage attacks.In the real applications,the leakage is unbounded.That is,a practical cryptography scheme should keep its original security in the continuous leakage setting.The previous continuous leakage-resilient IBE schemes either only achieve chosen-plaintext attacks security or the chosen-ciphertext attacks(CCA)security is proved in the selective identity model.Aiming to solve these problems,in this paper,we show how to construct the continuous leakage-resilient IBE scheme,and the scheme’s adaptive CCA security is proved in the standard model based on the hardness of decisional bilinear Diffie-Hellman exponent assumption.For any adversary,all elements in the ciphertext are random,and an adversary cannot obtain any leakage on the private key of user from the corresponding given ciphertext.Moreover,the leakage parameter of our proposal is independent of the plaintext space and has a constant size.

An Identity-Based Encryption Scheme with Compact Ciphertexts

This paper proposes an identity-based encryption scheme with the help of bilinear pairings, where the identity information of a user functions as the user＇s public key. The advantage of an identity-based public key system is that it can avoid public key certificates and certificate management. Our identity-based encryption scheme enjoys short ciphertexts and provable security against chosen-ciphertext attack （CCA）.

Revocable Hierarchical Identity-Based Broadcast Encryption

Hierarchical Identity-Based Broadcast Encryption （HIBBE） organizes users into a tree-like structure, and it allows users to delegate their decryption ability to subordinates and enable encryption to any subset of users while only intended users can decrypt. However, current HIBBE schemes do not support efficient revocation of private keys. Here, a new primitive called Revocable Hierarchical Identity-Based Broadcast Encryption （RHIBBE） is formalized that allows revocation of the HIBBE. Ciphertext indistinguishability is defined against the selectively Bounded Revocable Identity-Vector-Set and Chosen-Plaintext Attack （IND-sBRIVS-CPA）. An IND-sBRIVS-CPA secure RHIBBE scheme is constructed with efficient revocation on prime-order bilinear groups. The unbounded version of the scheme is also shown to be secure but a little weaker than the former under the decisional n-Weak Bilinear Diffie-Hellman inversion assumption.

(Identity-based)dual receiver encryption from lattice-based programmable hash functions with high min-entropy

Dual receiver encryption(DRE)is an important cryptographic primitive introduced by Diament et al.at CCS’04,which allows two independent receivers to decrypt a same ciphertext to obtain the same plaintext.This primitive is quite useful in designing combined public key cryptosystems and denial of service attack-resilient protocols.In this paper,we obtain some results as follows.·Using weak lattice-based programmable hash functions(wLPHF)with high min-entropy(Crypto’16),we give a generic IND-CCA secure DRE construction in the standard model.Furthermore,we get a concrete DRE scheme by instantiating a concrete wLPHF with high min-entropy.·For DRE notion in the identity-based setting,identity-based DRE(IB-DRE),basing on lattice-based programmable hash functions(LPHF)with high min-entropy,we give a framework of IND-ID-CPA secure IB-DRE construction in the standard model.When instantiating with concrete LPHFs with high min-entropy,we obtain five concrete IB-DRE schemes.

(Identity-based)dual receiver encryption from lattice-based programmable hash functions with high min-entropy

Dual receiver encryption(DRE)is an important cryptographic primitive introduced by Diament et al.at CCS’04,which allows two independent receivers to decrypt a same ciphertext to obtain the same plaintext.This primitive is quite useful in designing combined public key cryptosystems and denial of service attack-resilient protocols.In this paper,we obtain some results as follows.·Using weak lattice-based programmable hash functions(wLPHF)with high min-entropy(Crypto’16),we give a generic IND-CCA secure DRE construction in the standard model.Furthermore,we get a concrete DRE scheme by instantiating a concrete wLPHF with high min-entropy.·For DRE notion in the identity-based setting,identity-based DRE(IB-DRE),basing on lattice-based programmable hash functions(LPHF)with high min-entropy,we give a framework of IND-ID-CPA secure IB-DRE construction in the standard model.When instantiating with concrete LPHFs with high min-entropy,we obtain five concrete IB-DRE schemes.