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...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.展开更多
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, b...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.展开更多
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-insulat...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.展开更多
基金Rising-Star Program of Shanghai 2023 Science and Technology Innovation Action Plan(Yangfan Special Project),China(No.23YF1401000)Fundamental Research Funds for the Central Universities,China(No.2232022D-25)。
文摘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.
基金The National Hi-Tech Research and Development Program (863) of China (No. 2005AA145110)The Pudong New Area Technology Innovation Public Service Platform of China (No. PDP2005-04)
文摘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.
基金Supported by the Science and Technology Planned Projects of Wuhan, China (20061005119)
文摘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.
