Relative Generalized Rank Weight of Linear Codes and Its Applications to Network Coding

By extending the notion of minimum rank distance, this paper introduces two new relative code parameters of a linear code C_1 of length n over a field extension and its subcode C_2. One is called the relative dimension/intersection profile (RDIP), and the other is called the relative generalized rank weight (RGRW). We clarify their basic properties and the relation between the RGRW and the minimum rank distance. As applications of the RDIP and the RGRW, the security performance and the error correction capability of secure network coding, guaranteed independently of the underlying network code, are analyzed and clarified. We propose a construction of secure network coding scheme, and analyze its security performance and error correction capability as an example of applications of the RDIP and the RGRW. Silva and Kschischang showed the existence of a secure network coding in which no part of the secret message is revealed to the adversary even if any dim C_1-1 links are wiretapped, which is guaranteed over any underlying network code. However, the explicit construction of such a scheme remained an open problem. Our new construction is just one instance of secure network coding that solves this open problem.Comment: IEEEtran.cls, 25 pages, no figure, accepted for publication in IEEE Transactions on Information Theor

New Parameters of Linear Codes Expressing Security Performance of Universal Secure Network Coding

The universal secure network coding presented by Silva et al. realizes secure and reliable transmission of a secret message over any underlying network code, by using maximum rank distance codes. Inspired by their result, this paper considers the secure network coding based on arbitrary linear codes, and investigates its security performance and error correction capability that are guaranteed independently of the underlying network code. The security performance and error correction capability are said to be universal when they are independent of underlying network codes. This paper introduces new code parameters, the relative dimension/intersection profile (RDIP) and the relative generalized rank weight (RGRW) of linear codes. We reveal that the universal security performance and universal error correction capability of secure network coding are expressed in terms of the RDIP and RGRW of linear codes. The security and error correction of existing schemes are also analyzed as applications of the RDIP and RGRW.Comment: IEEEtran.cls, 8 pages, no figure. To appear in Proc. 50th Annual Allerton Conference on Communication, Control, and Computing (Allerton 2012). Version 2 added an exact expression of the universal error correction capability in terms of the relative generalized rank weigh

Development of a regulatable low-temperature protein expression system using the psychrotrophic bacterium, Shewanella livingstonensis Ac10, as the host

A low-temperature protein expression system is useful for the production of thermolabile proteins. We previously developed a system that enables constitutive protein production at low temperatures, using the psychrotrophic bacterium Shewanella livingstonensis Ac10 as the host. To increase the utility of this system, in the present study, we introduced a repressible promoter of the trp operon of this bacterium into the system. When ß-lactamase was produced under the control of this promoter at 18°C and 4°C, the yields were 75 and 33 mg/L-culture, respectively, in the absence of L-Trp, and the yields were decreased by 72% and 77%, respectively, in the presence of L-Trp. We also found that 3-indoleacrylic acid, a competitive inhibitor of the Escherichia coli trp repressor, increased the expression of the reporter gene. This repressible gene expression system would be useful for regulatable recombinant protein production at low temperatures

Apply blockchain technology to electric vehicle battery refueling

Battery swapping is a solution of electric vehicle (EV) battery refueling. For EV owners, the battery information and transaction’s correctness, openness, traceability and immutability is difficult to get guarantee in traditional centralized system. The trust lacking between EV owners and swapping station is caused, and becomes a big challenge to EV’s rapid development. An objective mechanism based on decentralized blockchain system is proposed to manage battery swapping and solve the trust lacking issue. With this solution, both battery’s life-cycle information and all operations histories are permanently saved in blockchain network. All key logics are driven by smart contracts, the battery price calculation and the digital currency exchange between EV owners and station are realized by smart contracts automatically and accurately. A primary prototype based on Ethereum is analyzed and implemented to illustrate the feasibility of managing battery swapping and refueling based on blockchain system to solve the trust lacking issue

A New (k,n)(k,n)-Threshold Secret Sharing Scheme and Its Extension

In Shamir\u27s $(k,n)$-threshold secret sharing scheme (threshold scheme), a heavy computational cost is required to make $n$ shares and recover the secret. As a solution to this problem, several fast threshold schemes have been proposed. This paper proposes a new (k,n)$-threshold scheme. For the purpose to realize high performance, the proposed scheme uses just EXCLUSIVE-OR(XOR) operations to make shares and recover the secret. We prove that the proposed scheme is a {\it perfect} secret sharing scheme, every combination of$k$or more participants can recover the secret, but every group of less than$k$participants cannot obtain any information about the secret. Moreover, we show that the proposed scheme is an {\it ideal} secret sharing scheme similar to Shamir\u27s scheme, which is a {\it perfect} scheme such that every bit-size of shares equals that of the secret. We also evaluate the efficiency of the scheme, and show that our scheme realizes operations that are much faster than Shamir\u27s. Furthermore, from the aspect of both computational cost and storage usage, we also introduce how to extend the proposed scheme to a new$(k,L,n)$-threshold {\it ramp} scheme similar to the existing {\it ramp} scheme based on Shamir\u27s scheme