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This paper proposes a secure routing protocol based on an ad hoc on-demand distance vector to simultaneously achieve communication efficiency and security. Many studies have discussed secure protocols. However, conventional protocols tend to exhibit low communication efficiencies owing to the long packets required by digital signatures, specifically in large-scale networks. Hence, our proposed method aims to allow the intermediate node to initiate a route reply (RREP), which is prohibited in conventional protocols because of digital signature restrictions. Based on an ID-based signature, the proposed protocol allows each intermediate node to hold a packet received from a specific node in the past. Each node then appends it to the route request of another node and generates its own signed RREP. This procedure guarantees that a third party holds the route to the destination. Theoretical evaluations demonstrate that the proposed method outperforms the communication efficiency of conventional secure protocols. We measured the time required for routing (i.e., the sum of communication and cryptographic calculation times) using a Raspberry Pi with C language. We show that the proposed protocol can improve the average routing time by more than 3× compared with conventional methods when 30 relay nodes are randomly distributed in a 300-square meter area. [ABSTRACT FROM AUTHOR]

Conventional digital watermark systems assume that the distributor (server) is a completely reliable organization. If the server is not a reliable organization, in a conventional system it is possible that suspicion may fall on a user who is not illegally distributing. Several methods have been proposed to handle this problem. In these methods, however, the system is essentially composed of two kinds of entities: the agent and the users. There is no discussion of a system composed of three entities—authors, agent, and users—where secondary distribution takes place from the author to an agent and then to the users. This paper proposes a digital watermark system that can prevent illegal conduct in a secondary distribution system composed of three types of entities—authors, agent, and users. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(6): 76–85, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1151 [ABSTRACT FROM AUTHOR]

The main search functions realized by searchable encryption can be classified into the search function using one query and that using multiple queries. Searchable encryption using one query has been widely studied and researched; however, few searchable encryption methods can accommodate the search function using multiple queries. Additionally, most of the methods proposed thus far utilize the concept of index search. Therefore, an additional process of updating or deleting an index when new documents are added or removed is required, increasing the overall computational cost. Furthermore, a document that is not registered in the index cannot be searched. Therefore, herein, using a secret sharing scheme that is known to offer a low computational cost, we propose a method that can realize the direct search function over sentences using the conjunctive search function without the construction of any index. We also propose a method that realizes the search function with multiple search queries using the disjunctive search function. Additionally, we implement our proposed methods, and demonstrate that they can perform a direct search over sentences using multiple keywords. [ABSTRACT FROM AUTHOR]

The Berlekamp-Massey algorithm and the Euclidean algorithm are well known as decoding methods for Reed-Solomon codes. Sakata's algorithm, which finds the minimal set of polynomials that generate a given two-dimensional (2-D) array, is used as a decoding method for algebraic-geometric codes; Reed-Solomon codes are a subclass of the algebraic-geometric codes. The Sakata algorithm is an extension of the Berlekamp-Massey algorithm to two dimensions, hut there is no corresponding extension of the Euclidean algorithm to give it the edge in implementation. Theorems are presented here to demonstrate in general the equivalence between the Berlekamp-Massey algorithm and the Euclidean algorithm and from these theorems a 2-D Euclidean algorithm that corresponds to the 2-D Berlekamp-Massey algorithm (Sakata algorithm) is developed. Moreover, the algorithms described here correspond to the multidimensional Berlekamp-Massey algorithm and to the Kamiya-Miura algorithm, a modification of the Sakata algorithm. The algorithms proposed in this paper may be implemented at high speeds with parallel processing, a difficult task for the Berlekamp-Massey algorithm. [ABSTRACT FROM AUTHOR]

The Montgomery method is known as a method to execute modular multiplications without using divisions, and several systolic arrays have beat proposed for execution of the Montgomery method. A problem in the Montgomery method is that the number of output bits may exceed the number of input bits. In the past implementations, the size of the output must be examined and corrected each time the method is executed, which is an obstacle in improving the efficiency. From such a viewpoint, this paper derives the general condition so that the size of the output need not be examined each time the Montgomery method is executed and proposes two types of systolic arrays that execute the Montgomery method under that condition. These arrays are more efficient than the systolic array proposed previously by the authors for modular multiplications. The method is effective and practical for VLSI implementation such as on a chip. [ABSTRACT FROM AUTHOR]

Until now, no code has been reported which can algebraically correct errors consisting in bit deletions or insertions (synchronization errors) and errors by bit inversion (inversion errors) when they occur simultaneously. This paper proposes a code that can algebraically correct simultaneously occurring synchronization and inversion errors as long as they occur within the range of a single byte. The proposed code is practical, involving very simple operations, and can correct synchronization and inversion errors in an information sequence of k bytes, where 1 byte consists of q bits, when the errors occur within a single byte. The redundancy and effectiveness of the code also are discussed. [ABSTRACT FROM AUTHOR]

Modular multiplication: R = A · B mod N (where A, B, N, and R are integers) is an essential operation used in public-key cryptosystems such as RSA, El Gamal, and Rabin. Thus, if high-speed modular multiplication circuits can be constructed, these cryptosystems can operate at high speeds. In this paper, we show how to construct, with a high-speed modular multiplication circuit which employs parallel processing methods using systolic arrays, a circuit which performs modular exponentiation by repeated modular multiplication. In particular, we demonstrate its validity by using the RSA scheme as a first concrete example. Since a circuit using the method of this paper as its construction rule has simple and regular structure, it provides an optimal construction of a high-speed RSA chip in VLSI. The method is also applicable for a simple implementation of the RSA scheme with small-sized chips. In this case, the number of chips needed by this method (the circuit size) allows the practical realization of proportionately higher speeds. Flexibility can be achieved for a change in the number of key bits by a corresponding increase or decrease in the number of chips. [ABSTRACT FROM AUTHOR]

The systolic array is a scheme for parallel processing and provides an architecture which is suited to a high-speed operation. Consequently, the systolic array has been applied to the system for which the high-speed processing is required, but not to the system for which the reduction of the circuit scale is required. This paper demonstrates that the principle of the systolic array can be applied as a means of reducing the circuit scale. By the proposed method, the circuit scale can be reduced in the system based on the systolic array, without an appreciable modification of the connection in the array and the control. This paper discusses the Reed-Solomon (RS) coder-decoder based on the systolic array as an example, and shows that the circuit scale can be reduced simply. By this system, the RS coder-decoder can be realized in a simple way by the small circuit scale, corresponding to the processing speed of the system. [ABSTRACT FROM AUTHOR]