Two operation homomorphic sharing schemes were introduced by Frankel and Desmedt. They have proved that if the set of keys is a Boolean algebra or a finite field, then there does not exist a two operation homomorphic ...Two operation homomorphic sharing schemes were introduced by Frankel and Desmedt. They have proved that if the set of keys is a Boolean algebra or a finite field, then there does not exist a two operation homomorphic sharing scheme. In this paper it is proved that there do not exist perfect two operation homomorphic sharing schemes over finite rings with identities. A necessary condition for the existence of perfect two operation sharing schemes over finite rings without identities is given.展开更多
A(t,n)threshold secret sharing scheme is a fundamental tool in many security applications such as cloud computing and multiparty computing.In conventional threshold secret sharing schemes,like Shamir’s scheme based o...A(t,n)threshold secret sharing scheme is a fundamental tool in many security applications such as cloud computing and multiparty computing.In conventional threshold secret sharing schemes,like Shamir’s scheme based on a univariate polynomial,additional communication key share scheme is needed for shareholders to protect the secrecy of their shares if secret reconstruction is performed over a network.In the secret reconstruction,the threshold changeable secret sharing(TCSS)allows the threshold to be a dynamic value so that if some shares have been compromised in a given time,it needs more shares to reconstruct the secret.Recently,a new secret sharing scheme based on a bivariate polynomial is proposed in which shares generated initially by a dealer can be used not only to reconstruct the secret but also to protect the secrecy of shares when the secret reconstruction is performed over a network.In this paper,we further extend this scheme to enable it to be a TCSS without any modification.Our proposed TCSS is dealer-free and non-interactive.Shares generated by a dealer in our scheme can serve for three purposes,(a)to reconstruct a secret;(b)to protect the secrecy of shares if secret reconstruction is performed over a network;and(c)to enable the threshold changeable property.展开更多
The probabilities of the state transitions of the initial value S 0 in the S table of RC4 are described by a kind of bistochastic matrices, and then a computational formula for such bistochastic matrices is given, by ...The probabilities of the state transitions of the initial value S 0 in the S table of RC4 are described by a kind of bistochastic matrices, and then a computational formula for such bistochastic matrices is given, by which the mathematical expectation of the number of fixed points in the key extending algorithm of RC4 is obtained. As a result, a statistical weakness of the key extending algorithm of RC4 is presented.展开更多
文摘Two operation homomorphic sharing schemes were introduced by Frankel and Desmedt. They have proved that if the set of keys is a Boolean algebra or a finite field, then there does not exist a two operation homomorphic sharing scheme. In this paper it is proved that there do not exist perfect two operation homomorphic sharing schemes over finite rings with identities. A necessary condition for the existence of perfect two operation sharing schemes over finite rings without identities is given.
基金This work was partially supported by the National Natural Science Foundation of China(Grants Nos.61772224,62072133)the Fundamental Research Funds for the Central Universities(CCNU19TS019)+1 种基金the Research Planning Project of National Language Committee(YB135-40)the key projects of Guangxi Natural Science Foundation(2018GXNSFDA281040).Lein Harn,Chingfang Hsu and Zhe Xia contributed equally to this work.
文摘A(t,n)threshold secret sharing scheme is a fundamental tool in many security applications such as cloud computing and multiparty computing.In conventional threshold secret sharing schemes,like Shamir’s scheme based on a univariate polynomial,additional communication key share scheme is needed for shareholders to protect the secrecy of their shares if secret reconstruction is performed over a network.In the secret reconstruction,the threshold changeable secret sharing(TCSS)allows the threshold to be a dynamic value so that if some shares have been compromised in a given time,it needs more shares to reconstruct the secret.Recently,a new secret sharing scheme based on a bivariate polynomial is proposed in which shares generated initially by a dealer can be used not only to reconstruct the secret but also to protect the secrecy of shares when the secret reconstruction is performed over a network.In this paper,we further extend this scheme to enable it to be a TCSS without any modification.Our proposed TCSS is dealer-free and non-interactive.Shares generated by a dealer in our scheme can serve for three purposes,(a)to reconstruct a secret;(b)to protect the secrecy of shares if secret reconstruction is performed over a network;and(c)to enable the threshold changeable property.
基金the National Natural Science Foundation of China (Grant No. 10371061)
文摘The probabilities of the state transitions of the initial value S 0 in the S table of RC4 are described by a kind of bistochastic matrices, and then a computational formula for such bistochastic matrices is given, by which the mathematical expectation of the number of fixed points in the key extending algorithm of RC4 is obtained. As a result, a statistical weakness of the key extending algorithm of RC4 is presented.
