This paper focuses on the instantiation of random oracles in public key encryption schemes. A misunderstanding in the former instantiations is pointed out and analyzed. A method of using this primitive as a substituti...This paper focuses on the instantiation of random oracles in public key encryption schemes. A misunderstanding in the former instantiations is pointed out and analyzed. A method of using this primitive as a substitution of random oracles is also proposed. The partial and full instantiations of random oracles in optimal asymmetric encryption padding （OAEP） implemented by pseudorandom functions are described and the resulted schemes are proven to be indistinguishable secure against adaptive chosen ciphertext attack （IND-CCA2） secure. Using this method, one can transform a practical public key encryption scheme secure in the random oracle model into a standard-model secure scheme. The security of the scheme is based on computational assumptions, which is weaker than decisional assumptions used in Cramer- Shoup like schemes.展开更多
In this paper, an efficient hybrid proxy re-encryption scheme that allows the transformation of the ciphertexts in a traditional public key cryptosystem into the ciphertexts in an identity-based system is proposed. Th...In this paper, an efficient hybrid proxy re-encryption scheme that allows the transformation of the ciphertexts in a traditional public key cryptosystem into the ciphertexts in an identity-based system is proposed. The scheme is non-interactive, unidirectional and collude ＂safe＂. Furthermore, it is compatible with current IBE （identity-based encryption） deployments. The scheme has chosen ciphertext security in the random oracle model assuming the hardness of the Decisional Bilinear Diffie-Hellman problem.展开更多
现有的基于SM2环签名方案存在私钥泄露的风险,不诚实的密钥生成中心(KGC)有能力监听和伪造实体间的通信,为了克服该不足,提出基于SM2的无证书环签名方案CLRS-SM(CertificateLess Ring Signing scheme based on SM2)。该方案中用户的私...现有的基于SM2环签名方案存在私钥泄露的风险,不诚实的密钥生成中心(KGC)有能力监听和伪造实体间的通信,为了克服该不足,提出基于SM2的无证书环签名方案CLRS-SM(CertificateLess Ring Signing scheme based on SM2)。该方案中用户的私钥由各自独立的2部分组成,一部分是由KGC根据用户的身份和系统主密钥计算的用户的部分私钥,另一部分是用户自身随机选择的一个秘密值。因此,即使恶意KGC泄露部分私钥,攻击者也无法获得用户的整个私钥。该方案的安全性规约为离散对数问题,并在随机预言模型下证明了它具有不可伪造性和无条件匿名性。实验结果表明,与现有的基于SM2环签名方案相比,所提方案能以仅多出0.18%的计算量抵抗恶意密钥生成中心攻击,具有更高的安全性。展开更多
Anonymous proxy signature scheme can provide the privacy protection for the proxy signer. Recently, Yu et al. proposed an anonymous proxy signature, which can be viewed as the organic combination of proxy signature an...Anonymous proxy signature scheme can provide the privacy protection for the proxy signer. Recently, Yu et al. proposed an anonymous proxy signature, which can be viewed as the organic combination of proxy signature and ring signature. However, the efficiency is low. In this paper, we propose an efficient and secure proxy signature with the properties of anonymity and traceability, and it is provably secure in the random oracle model. Compared with Yu et al.＇s scheme, the scheme has higher efficiency.展开更多
基金Supported by the National Basic Research Program of China (973 Program) (2007CB311201)the National High-Technology Research and Development Program of China (863 Program) (2006AA01Z427)the National Natural Science Foundation of China (60673073)
文摘This paper focuses on the instantiation of random oracles in public key encryption schemes. A misunderstanding in the former instantiations is pointed out and analyzed. A method of using this primitive as a substitution of random oracles is also proposed. The partial and full instantiations of random oracles in optimal asymmetric encryption padding （OAEP） implemented by pseudorandom functions are described and the resulted schemes are proven to be indistinguishable secure against adaptive chosen ciphertext attack （IND-CCA2） secure. Using this method, one can transform a practical public key encryption scheme secure in the random oracle model into a standard-model secure scheme. The security of the scheme is based on computational assumptions, which is weaker than decisional assumptions used in Cramer- Shoup like schemes.
基金Supported by the National Natural Science Foundation of China (60673070)the Natural Science Foundation of Jiangsu Province, China (BK2006217)
文摘In this paper, an efficient hybrid proxy re-encryption scheme that allows the transformation of the ciphertexts in a traditional public key cryptosystem into the ciphertexts in an identity-based system is proposed. The scheme is non-interactive, unidirectional and collude ＂safe＂. Furthermore, it is compatible with current IBE （identity-based encryption） deployments. The scheme has chosen ciphertext security in the random oracle model assuming the hardness of the Decisional Bilinear Diffie-Hellman problem.
文摘现有的基于SM2环签名方案存在私钥泄露的风险,不诚实的密钥生成中心(KGC)有能力监听和伪造实体间的通信,为了克服该不足,提出基于SM2的无证书环签名方案CLRS-SM(CertificateLess Ring Signing scheme based on SM2)。该方案中用户的私钥由各自独立的2部分组成,一部分是由KGC根据用户的身份和系统主密钥计算的用户的部分私钥,另一部分是用户自身随机选择的一个秘密值。因此,即使恶意KGC泄露部分私钥,攻击者也无法获得用户的整个私钥。该方案的安全性规约为离散对数问题,并在随机预言模型下证明了它具有不可伪造性和无条件匿名性。实验结果表明,与现有的基于SM2环签名方案相比,所提方案能以仅多出0.18%的计算量抵抗恶意密钥生成中心攻击,具有更高的安全性。
基金supported by the National Natural Science Foundation of China (61121061, 90812001, 61272519)
文摘Anonymous proxy signature scheme can provide the privacy protection for the proxy signer. Recently, Yu et al. proposed an anonymous proxy signature, which can be viewed as the organic combination of proxy signature and ring signature. However, the efficiency is low. In this paper, we propose an efficient and secure proxy signature with the properties of anonymity and traceability, and it is provably secure in the random oracle model. Compared with Yu et al.＇s scheme, the scheme has higher efficiency.
