Due to forward-secure-digital-signature＇s capability of effectively reducing loss caused by exposure of secret keys and significant in-application benefits of blind signature aiming at protecting senders＇ privacy, t...Due to forward-secure-digital-signature＇s capability of effectively reducing loss caused by exposure of secret keys and significant in-application benefits of blind signature aiming at protecting senders＇ privacy, they have been hot spots for decades in the field of cryptography. Illuminated by the integration of forward secure digital signature and blind signature, based on the variants of E1Gamal and assumption of difficulty in solving the discrete logarithm problem in galois field, a forward-secure weak blind signature scheme and a forward-secure strong blind signature scheme are proposed and their security is analyzed thoroughly in this paper. It turns out that forward security, blindness and aptitude of resisting forging attack demonstrated by these two schemes benefit a lot theoretically and practically.展开更多
The key challenge of dynamic peer communication is how to realize secure and efficient group key manage-ment.A two rounds key agreement protocol for dynamic peer group(DPG)is proposed in this paper.The protocol,which ...The key challenge of dynamic peer communication is how to realize secure and efficient group key manage-ment.A two rounds key agreement protocol for dynamic peer group(DPG)is proposed in this paper.The protocol,which was obtained by combining the ElGamal encryption scheme with the ElGamal signature scheme,is efficient and simple.The protocol is proven secure against passive attack by using indistinguishable method.Moreover,both perfect forward secrecy(PFS)and key independence(KI)were achieved.Because the protocol is based on the broadcast channel,it is also suitable for key agreement in wireless communications,especially in ad-hoc networks.展开更多
The discrete logarithm method is the foundation of many public key algorithms. However, one type of key, defined as a weak-key, reduces the security of public key cryptosystems based on the discrete logarithm method. ...The discrete logarithm method is the foundation of many public key algorithms. However, one type of key, defined as a weak-key, reduces the security of public key cryptosystems based on the discrete logarithm method. The weak-key occurs if the public key is a factor or multiple of the primitive element, in which case the user＇s private key is not needed but can be obtained based on the character of the public key. An algorithm is presented that can easily test whether there is a weak-key in the cryptosystem. An example is given to show that an attack can be completed for the Elgamal digital signature if a weak-key exists, therefore validating the danger of weak-keys. Methods are given to prevent the generation of these weak-keys.展开更多
基金This work was supported by the National Natural Science Foundation of China for Grant 60673127, the National High Technology Research and Development Program of China （863 Program） for Grant 2007AA01Z404, the Science ＆ Technology Pillar Program of Jiangsu Province for Grant BE2008135, the Electronic Development Foundation of the Ministry of Information Industry, Funding of Jiangsu Innovation Program for Graduate Education for Grant CX10B112Z, Funding for Outstanding Doctoral Dissertation in NUAA for Grant BCXJ10-07, Research Funding of Nanjing University of Aeronautics and Astronautics for Grant NS2010101 and Jiangsu Province Postdoctoral Science Foundation. We wish to thank the above support, under which the present work is possible.
文摘Due to forward-secure-digital-signature＇s capability of effectively reducing loss caused by exposure of secret keys and significant in-application benefits of blind signature aiming at protecting senders＇ privacy, they have been hot spots for decades in the field of cryptography. Illuminated by the integration of forward secure digital signature and blind signature, based on the variants of E1Gamal and assumption of difficulty in solving the discrete logarithm problem in galois field, a forward-secure weak blind signature scheme and a forward-secure strong blind signature scheme are proposed and their security is analyzed thoroughly in this paper. It turns out that forward security, blindness and aptitude of resisting forging attack demonstrated by these two schemes benefit a lot theoretically and practically.
基金supported by the National Natural Science Foundation of China(Grant No.90304009).
文摘The key challenge of dynamic peer communication is how to realize secure and efficient group key manage-ment.A two rounds key agreement protocol for dynamic peer group(DPG)is proposed in this paper.The protocol,which was obtained by combining the ElGamal encryption scheme with the ElGamal signature scheme,is efficient and simple.The protocol is proven secure against passive attack by using indistinguishable method.Moreover,both perfect forward secrecy(PFS)and key independence(KI)were achieved.Because the protocol is based on the broadcast channel,it is also suitable for key agreement in wireless communications,especially in ad-hoc networks.
基金Supported by the National Key Basic Research and Development (973) Program (No. 2003CB314805) and the National Natural Science Foundation of China (No. 90304014)
文摘The discrete logarithm method is the foundation of many public key algorithms. However, one type of key, defined as a weak-key, reduces the security of public key cryptosystems based on the discrete logarithm method. The weak-key occurs if the public key is a factor or multiple of the primitive element, in which case the user＇s private key is not needed but can be obtained based on the character of the public key. An algorithm is presented that can easily test whether there is a weak-key in the cryptosystem. An example is given to show that an attack can be completed for the Elgamal digital signature if a weak-key exists, therefore validating the danger of weak-keys. Methods are given to prevent the generation of these weak-keys.
