Escrow-Free Certificate-Based Authenticated Key Agreement Protocol from Pairings

Key agreement protocols are essential for secure communications. In this paper, to solve the inherent key escrow problem of identity-based cryptography, an escrow-free certificate-based authenticated key agreement （CB-AK） protocol with perfect forward secrecy is proposed. Our protocol makes use of pairings on elliptic curves. The protocol is described and its properties are discussed though comparison with Smart＇s protocol.

Improved ID-Based Signature Scheme Solving Key Escrow

Key escrow is an inherent disadvantage for traditional ID-based cryptosystem, i.e., the dishonest private key generator (PKG) can forge the signature of any user, meanwhile, the user can deny the signature actually signed by him/herself. To avoid the keyescrow problem, an ID-based signature scheme was presented without trusted PKG. The exact proof of security was presented to demonstrate that our scheme is secure against existential forgery on adaptively chosen message and ID attacks assuming the complexity of computational Diffie-Hellman (CDH) problem. Compared with other signature schemes, the proposed scheme is more efficient.

Towards accountable authority attribute-based encryption

An accountable authority attribute-based encryption （A-ABE） scheme is presented in this paper. The notion of accountable authority identity-based encryption （A-IBE） was first introduced by Goyal at Crypto＇07. It is a novel approach to mitigate the （inherent） key escrow problem in identity-based cryptosystems. In this work, the concept of accountable authority to attribute-based encryption （ABE） setting is generalized for the first time, and then a construction is given. The scheme non-trivially integrates an A-IBE scheme proposed by Libert et al. with an ABE scheme. In our construction, a user will be identified by a pair （ id, o~）, where id denotes the user＇ s identity and ω denotes the set of attributes associated to the user. In addition, our construction is shown to be secure under some reasonable assumptions.

A privacy-preserving data aggregation system based on blockchain in VANET

In the realm of vehicular ad hoc networks(VANETs),data aggregation plays a pivotal role in bringing together data from multiple vehicles for further processing and sharing.Erroneous data feedback can significantly impact vehicle operations,control,and overall safety,necessitating the assurance of security in vehicular data aggregation.Addressing the security risks and challenges inherent in data aggregation within VANETs,this paper introduces a blockchain-based scheme for secure and anonymous data aggregation.The proposed scheme integrates cloud computing with blockchain technology,presenting a novel blockchain-based data aggregation system that robustly supports efficient and secure data collection in VANETs.Leveraging key escrow resilience mechanisms,the solution ensures the security of system keys,preventing the security problems caused by keys generated by third parties alone in the past.Furthermore,through secondary data aggregation,fine-grained data aggregation is achieved,providing effective support for cloud services in VANETs.The effectiveness of the proposed scheme is confirmed through security analysis and performance evaluations,demonstrating superior computational and communication efficiency compared existing alternatives.

A threshold key escrow scheme based on public key cryptosystem

In key escrow field it is important to solve the problem thatuser's secret key completely depends on the trusted escrow agency. In 1995, some methods of solving the problem were presented. But these methods are no better than that of directly using threshold cryptography. In this paper, we present a common pattern of threshold key escrow scheme based on public key cryptosystem, and a detailed design based on the improved RSA algorithm is given. The above problem is solved by this scheme.

An Improved Ring Signature Scheme without Trusted Key Generation Center for Wireless Sensor Network

Security of wireless sensor network （WSN） is a considerable challenge, because of limitation in energy, communication bandwidth and storage. ID-based cryptosystem without checking and storing certificate is a suitable way used in WSN. But key escrow is an inherent disadvantage for traditional ID-based cryptosystem, i.e., the dishonest key generation center （KGC） can forge the signature of any node and on the other hand the node can deny the signature actually signed by him/herself. To solving this problem, we propose an ID-based ring signature scheme without trusted KGC. We also present the accurate secure proof to prove that our scheme is secure against existential forgery on adaptively chosen message and ID attacks assuming the complexity of computational Diffie-Hellman （CDH） problem. Compared with other ring signature schemes, we think proposed scheme is more efficient.

Efficient and Provably-Secure Certificateless Proxy Re-encryption Scheme for Secure Cloud Data Sharing

In current cloud computing system, large amounts of sensitive data are shared to other cloud users. To keep these data confidentiality, data owners should encrypt their data before outsourcing. We choose proxy reencryption （PRE） as the cloud data encryption technique. In a PRE system, a semi-trusted proxy can transform a ciphertext under one public key into a ciphertext of the same message under another public key, but the proxy cannot gain any information about the message. In this paper, we propose a certificateless PRE （CL-PRE） scheme without pairings. The security of the proposed scheme can be proved to be equivalent to the computational Dire- Hellman （CDH） problem in the random oracle model. Compared with other existing CL-PRE schemes, our scheme requires less computation cost and is significantly more efficient. The new scheme does not need the public key certificates to guarantee validity of public keys and solves the key escrow problem in identity-based public key cryptography.

EFFICIENT CERTIFICATELESS THRESHOLD SIGNATURES WITHOUT RANDOM ORACLES

This paper defines the security notion for Certificateless Threshold Signatures （CLTHS）. Different from the adversarial model defined by Wang, et al. （2007）, our definition considers Type I and Type II adversary separately. At the same time, the authors develop the simulatability and relationship between certificateless threshold signature and the underlying certificateless signature. We also propose the first CLTHS scheme which is proved existentially unforgeable against adaptively chosen message attack without random oracles. Compared with the previous scheme by Wang, et al. （2007）, our scheme does not use hash function and is more efficient.

A Practical Identity-Based Signature Scheme

Many identity-based signature （IBS） schemes solving key escrow were proposed, But the updating of the private keys wasn＇t discussed in these literatures. For the problem of key update, an identity-based key-insulated signature scheme with secure key-updates has been proposed. But their scheme inherited the key escrow property. In this paper, we propose a new identity-based strong key-insulated signature scheme without key escrow. It makes the IBS scheme more applicable to the real world. After analyzing the security and the performance, an application example in E-passport passive authentication scenario is described.