Keccak is one of the five hash functions selected for the final round of the SHA-3 competition,and its inner primitive is a permutation called Keccak-f.In this paper,we observe that for the inverse of the only nonline...Keccak is one of the five hash functions selected for the final round of the SHA-3 competition,and its inner primitive is a permutation called Keccak-f.In this paper,we observe that for the inverse of the only nonlinear transformation in Keccak-f,the algebraic degree of any output coordinate and the one of the product of any two output coordinates are both 3,which is 2 less than its size of 5.Combining this observation with a proposition on the upper bound of the degree of iterated permutations,we improve the zero-sum distinguisher for the Keccak-f permutation with full 24 rounds by lowering the size of the zero-sum partition from 21590 to 21575.展开更多
Partially blind signatures are introduced on the basis of blind signatures,which not only retain the advantages of blind signatures,but also solve the contradiction between anonymity and controllability in blind signa...Partially blind signatures are introduced on the basis of blind signatures,which not only retain the advantages of blind signatures,but also solve the contradiction between anonymity and controllability in blind signatures.With the development of quantum computing technology,it becomes more urgent to construct secure partially blind signature schemes in quantum environments.In this paper,we present a new partially blind signature scheme and prove the security under the Ring-SIS assumption in the random oracle model.To avoid the restart problem of signature schemes caused by rejection sampling,a large number of random numbers are sampled in advance,so that they only need to be re-selected at the current stage without terminating the whole signature process when the conditions are not met.In addition,the hash tree technology is used to reduce communication costs and improve interactive performance.In order to avoid the errors in the security proof of the previous scheme,our proof builds upon and extends the modular framework for blind signatures of Hauck et al.and the correctness,partial blindness,and one-more unforgeability of the scheme are proved in detail according to the properties of the linear hash function.展开更多
When developing programs or websites, it is very convenient to use relational databases, which contain powerful and convenient tools that allow to work with data very flexibly and get the necessary information in a ma...When developing programs or websites, it is very convenient to use relational databases, which contain powerful and convenient tools that allow to work with data very flexibly and get the necessary information in a matter of milliseconds. A relational database consists of tables and records in these tables, each table must have a primary key, in particular, it can be a number of BIGINT type, which is a unique index of a record in the table, which allows to fetch operation with maximum speed and O (1) complexity. After the operation of writing a row to the table of database, the program receives the row identifier ID in the form of a number, and in the future this ID can be used to obtain this record. In the case of a website, this could be the GET method of the http protocol with the entry ID in the request. But very often it happens that the transmission of an identifier in the clear form is not safe, both for business reasons and for security reasons of access to information. And in this case, it is necessary to create additional functionality for checking access rights and come up with a way to encode data in such a way that it would be impossible to determine the record identifier, and this, in turn, leads to the fact that the program code becomes much more complicated and also increases the amount of data, necessary to ensure the operation of the program. This article presents an algorithm that solves these problems “on the fly” without complicating the application logic and does not require resources to store additional information. Also, this algorithm is very reliable since it is based on the use of hash functions and synthesized as a result of many years of work related to writing complex systems that require an increased level of data security and program performance.展开更多
基金supported by the National Natural Science Foundation of China (60573032,60773092 and 61073149)Research Fund for the Doctoral Program of Higher Education of China (20090073110027)
文摘Keccak is one of the five hash functions selected for the final round of the SHA-3 competition,and its inner primitive is a permutation called Keccak-f.In this paper,we observe that for the inverse of the only nonlinear transformation in Keccak-f,the algebraic degree of any output coordinate and the one of the product of any two output coordinates are both 3,which is 2 less than its size of 5.Combining this observation with a proposition on the upper bound of the degree of iterated permutations,we improve the zero-sum distinguisher for the Keccak-f permutation with full 24 rounds by lowering the size of the zero-sum partition from 21590 to 21575.
基金supported in part by the Key Research and Development Program of Shaanxi(2021 ZDLGY06-04)in part by the Youth Innovation Team of Shaanxi Universities.The review of this article was coordinated by Dr.Changyu Dong.
文摘Partially blind signatures are introduced on the basis of blind signatures,which not only retain the advantages of blind signatures,but also solve the contradiction between anonymity and controllability in blind signatures.With the development of quantum computing technology,it becomes more urgent to construct secure partially blind signature schemes in quantum environments.In this paper,we present a new partially blind signature scheme and prove the security under the Ring-SIS assumption in the random oracle model.To avoid the restart problem of signature schemes caused by rejection sampling,a large number of random numbers are sampled in advance,so that they only need to be re-selected at the current stage without terminating the whole signature process when the conditions are not met.In addition,the hash tree technology is used to reduce communication costs and improve interactive performance.In order to avoid the errors in the security proof of the previous scheme,our proof builds upon and extends the modular framework for blind signatures of Hauck et al.and the correctness,partial blindness,and one-more unforgeability of the scheme are proved in detail according to the properties of the linear hash function.
文摘When developing programs or websites, it is very convenient to use relational databases, which contain powerful and convenient tools that allow to work with data very flexibly and get the necessary information in a matter of milliseconds. A relational database consists of tables and records in these tables, each table must have a primary key, in particular, it can be a number of BIGINT type, which is a unique index of a record in the table, which allows to fetch operation with maximum speed and O (1) complexity. After the operation of writing a row to the table of database, the program receives the row identifier ID in the form of a number, and in the future this ID can be used to obtain this record. In the case of a website, this could be the GET method of the http protocol with the entry ID in the request. But very often it happens that the transmission of an identifier in the clear form is not safe, both for business reasons and for security reasons of access to information. And in this case, it is necessary to create additional functionality for checking access rights and come up with a way to encode data in such a way that it would be impossible to determine the record identifier, and this, in turn, leads to the fact that the program code becomes much more complicated and also increases the amount of data, necessary to ensure the operation of the program. This article presents an algorithm that solves these problems “on the fly” without complicating the application logic and does not require resources to store additional information. Also, this algorithm is very reliable since it is based on the use of hash functions and synthesized as a result of many years of work related to writing complex systems that require an increased level of data security and program performance.
