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.

IDENTITY-BASED MULTISIGNATURE AND AGGREGATE SIGNATURE SCHEMES FROM M-TORSION GROUPS

An identity-based multisignature scheme and an identity-based aggregate signature scheme are proposed in this paper. They are both from m-torsion groups on super-singular elliptic curves or hyper-elliptic curves and based on the recently proposed identity-based signature scheme of Cha and Cheon. Due to the sound properties of m-torsion groups and the base scheme, it turns out that our schemes are very simple and efficient. Both schemes are proven to be secure against adaptive chosen message attack in the random oracle model under the normal security notions with the assumption that the Computational Diffie-Hellman problem is hard in the m-torsion groups.

A Provably Secure Identity-based Authentication Multiple Key Agreement Protocol

An authentication multiple key agreement protocol allows the users to compute more than one session keys in an authentication way. In the paper,an identity-based authentication multiple key agreement protocol is proposed. Its authentication part is proven secure against existential forgery on adaptively chosen message and ID attacks under the random oracle model upon the CDH assumptions. The session keys are proven secure in a formal CK security model under the random oracle model upon the CBDH assumptions. Compared with the previous multiple key agreement protocols,it requires less communication cost.

IDENTITY-BASED KEY-INSULATED PROXY SIGNATURE

In proxy signature schemes,the proxy signer B is permitted to produce a signature on behalf of the original signer A. However,exposure of proxy signing keys can be the most devastating attack on a proxy signature scheme since any adversary can sign messages on behalf of the proxy signer. In this paper,we applied Dodis,et al.’s key-insulation mechanism and proposed an Identity-Based (ID-based) Key-Insulated Proxy Signature (IBKIPS) scheme with secure key-updates. The proposed scheme is strong key-insulated and perfectly key-insulated. Our scheme also supports unbounded period numbers and random-access key-updates.

An Identity-Based Strong Designated Verifier Proxy Signature Scheme

In a strong designated verifier proxy signature scheme, a proxy signer can generate proxy signature on behalf of an original signer, but only the designated verifier can verify the validity of the proxy signature. In this paper, we first define the security requirements for strong designated verifier proxy signature schemes. And then we construct an identity-based strong designated verifier proxy signature scheme. We argue that the proposed scheme satisfies all of the security requirements.

Identity-based ring signature scheme based on quadratic residues

Identity-based （ID-based） ring signature has drawn great concerns in recent years and many ID-based ring signature schemes have been proposed until now. Unfortunately, all of these ID-based ring signatures are constructed from bilinear pairings, a powerful but computationally expensive primitive. Hence, ID-based ring signature without pairing is of great interest in the field of cryptography. In this paper, the authors firstly propose an ID-based ring signature scheme based on quadratic residues. The proposed scheme is proved to be existentially unforgeable against adaptive chosen message-and-identity attack under the random oracle model, assuming the hardness of factoring. The proposed scheme is more efficient than those which are constructed from bilinear pairings.

Trusted Routing Based on Identity-Based Threshold Signature for Opportunistic Networks

In opportunistic Networks,compromised nodes can attack social context-based routing protocols by publishing false social attributes information.To solve this problem,we propose a security scheme based on the identity-based threshold signature which allows mobile nodes to jointly generate and distribute the secrets for social attributes in a totally self-organized way without the need of any centralized authority.New joining nodes can reconstruct their own social attribute signatures by getting enough partial signature services from encounter opportunities with the initial nodes.Mobile nodes need to testify whether the neighbors can provide valid attribute signatures for their routing advertisements in order to resist potential routing attacks.Simulation results show that:by implementing our security scheme,the network delivery probability of the social context-based routing protocol can be effectively improved when there are large numbers of compromised nodes in opportunistic networks.

Sharing of Encrypted Lock Keys in the Blockchain-Based Renting House System from Time- and Identity-Based Proxy Reencryption

To design an efficient protocol for sharing the encrypted lock keys in the renting house system,we introduce a new notion called time-and identitybased proxy reencryption(TIPRE)and the blockchain platform.Our CPA secure TIPRE scheme is constructed from Green et al.’s identity-based proxy reencryption scheme by adding the time property.In every time period,a time stamp authority generates a public key embedded with the current time stamp for each user.In our protocol for the renting house system,the TIPRE scheme is the primary building block,and the blockchain platform serves instead of a trusted third party,such as a real estate agency between landlords and tenants.The TIPRE scheme allows the landlord to change the lock key at each time period for safety.The blockchain platform allows the landlords and tenants to directly interact,and all of the interactions are recorded in the blockchain database to provide the desired security requirements,such as nonrepudiation and unforgeability.Finally,we provide the secure analysis of our protocol and test its performance by implementing it in the MacBook Pro and the Intel Edison development platforms.

Key-Private Identity-Based Proxy Re-Encryption

An identity-based proxy re-encryption scheme(IB-PRE)allows a semi-trusted proxy to convert an encryption under one identity to another without revealing the underlying message.Due to the fact that the proxy was semi-trusted,it should place as little trust as necessary to allow it to perform the translations.In some applications such as distributed file system,it demands the adversary cannot identify the sender and recipient’s identities.However,none of the exiting IB-PRE schemes satisfy this requirement.In this work,we first define the security model of key-private IB-PRE.Finally,we propose the first key-private IB-PRE scheme.Our scheme is chosen plaintext secure(CPA)and collusion resistant in the standard model.

Non-interactive identity-based threshold signature scheme without random oracles

A (t, n) threshold signature scheme distributes the secret key and hence the signing ability to n players in a way that any set of t+1 or more honest players can collaborate to sign, while any set of t players cannot. In this paper we propose an iden- tity-based threshold signature (IBTHS) scheme from bilinear pairings. The signing phase of our scheme is non-interactive, meaning that the signing players do not need to talk to each other. We prove our scheme secure (i.e., unforgeable and robust) in the standard model (i.e., without random oracles). No earlier proposed IBTHS scheme achieved even one of the features of being non-interactive (in the signing phase) and secure in the standard model.

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.

Identity-based authentication protocol for grid

Current grid authentication frameworks are achieved by applying the standard SSL authentication protocol （SAP）. The authentication process is very complicated, and therefore, the grid user is in a heavily loaded point both in computation and in communication. Based on identity-based architecture for grid （IBAG） and corresponding encryption and signature schemes, an identity-based authentication protocol for grid is proposed. Being certificate-free, the authentication protocol aligns well with the demands of grid computing. Through simulation testing, it is seen that the authentication protocol is more lightweight and efficient than SAP, especially the more lightweight user side. This contributes to the larger grid scalability.

An Identity-Based Scheme of Fair Exchange of Digital Signatures

Fair exchange of digital signatures is an important tool for signing digital contracts, e-payment and other electronic commerce actions. An ID-based scheme of fair exchange of digital signature is proposed in this paper. The protocol relies on a trusted third party, but is ＂optimistic＂, in that the third party is only needed in cases where one player attempts to cheat or simply crashes. The proposed scheme has properties of short signature, low computation and verification cost. It can realize exchange of digital signatures fairly and effic, iently. A key feature of our scheme is that it is identity-based, which needs no certificates and has a simple key management. To our best knowledge, this is the first identity based scheme of fair exchange of digital signatures.

An Improved Identity-Based Society Oriented Signature Scheme with Anonymous Signers

In this paper, we present an improved identity-based society oriented signature scheme with anonymous signers, which satisfies： （1） when members leave or join an organization, the public verification key and the signature verification procedure are unchanged; （2） a user participates in several organizations at the same time, her secret key is only related with her identity. However, no previous schemes have these two properties.

Improvement of Identity-Based Threshold Proxy Signature Scheme with Known Signers

In 2006, Bao et al proposed an identlty-based threshold proxy signature scheme with known signers. In this paper, we show that Bao et al＇s scheme is vulnerable to the forgery attack. An adversary can forge a valid threshold proxy signature for any message with knowing a previously valid threshold proxy signature. In addition, their scheme also suffers from the weakness that the proxy signers might change the threshold value. That is, the proxy signers can arbitrarily modify the threshold strategy without being detected by the original signer or verifiers, which might violate the original signer＇s intent. Furthermore, we propose an improved scheme that remedies the weaknesses of Bao et al＇s scheme. The improved scheme satisfies all secure requirements for threshold proxy signature.

An Identity-Based Secure and Optimal Authentication Scheme for the Cloud Computing Environment

Security is a critical issue in cloud computing(CC)because attackers can fabricate data by creating,copying,or deleting data with no user authorization.Most of the existing techniques make use of password-based authentication for encrypting data.Password-based schemes suffer from several issues and can be easily compromised.This paper presents a new concept of hybrid metaheuristic optimization as an identity-based secure and optimal authentication(HMO-ISOA)scheme for CC environments.The HMOISOA technique makes use of iris and fingerprint biometrics.Initially,the HMO-ISOA technique involves a directional local ternary quantized extrema pattern–based feature extraction process to extract features from the iris and fingerprint.Next,the features are fed into the hybrid social spider using the dragon fly algorithm to determine the optimal solution.This optimal solution acts as a key for an advanced encryption standard to encrypt and decrypt the data.A central benefit of determining the optimal value in this way is that the intruder cannot determine this value.The attacker also cannot work out which specific part of the fingerprint and iris feature values are acted upon as a key for the AES technique.Finally,the encrypted data can be saved in the cloud using a cloud simulator.Experimental analysis was performed on five fingerprint and iris images for a man-in-the-middle attack.The simulation outcome validated that the presented HMO-ISOA model achieved better results compared with other existing methods.

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.

Identity-based Verifiably Committed Signature Scheme without Random Oracles

An identity-based verifiably committed signature scheme (IB-VCS) was proposed, which is proved secure in the standard model (i.e., without random oracles). It enjoys the setup-free property and stand-alone property, both of which make an exchange protocol more practical. The scheme is unconditionally secure against the cheating signer, its security against the cheating verifier is reduced to the computational Diffie-Hellman (CDH) problem in the underlying group, it is secure against the cheating trusted third party if the underlying Paterson Schuldt's identity based signature (IBS) scheme is secure, which is proven true based on the CDH assumption in the standard model.

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.