The strong RSA assumption is an assumption that the following problem is hard to solve: Given an RSA modulus and a ciphertext, find a pair of plaintext and exponent corresponding to them. It differs from the standard RSA assumption in a sense that in the strong version, no exponent is given as an input. The strong RSA assumption is considered to be stronger than the RSA assumption, but their exact relationship is not known. We investigate the strength of the strong RSA assumption and show that the strong RSA assumption restricted to low exponents is equivalent to the assumption that RSA problem is intractable for any low exponent. We also show that in terms of algebraic computation, the strong RSA assumption is properly stronger than the RSA assumption if there exists an RSA modulus n such that gcd((n),3)=1 and RSA problem is intractable.

The generation of high repetition-rate optical pulse train using a passively mode-locked figure-8 fiber ring laser is presented. The laser employs a novel configuration incorporating a superstructure fiber Bragg grating. Pulse train with repetition rates up to 100GHz is possible and transform-limited pulses with pulsewidth below 1ps can be achieved with chirp compensation. The output pulses can further be reduced to 83fs with an external pulse compressor.

An 80 Gbit/s conventional and carrier-suppressed return-to-zero optical time-division multiplexing signal transmission over a 208 km standard single-mode fiber was experimentally demonstrated. This was achieved by using mid-span optical phase conjugation based on four-wave mixing in semiconductor optical amplifiers. In addition, it was confirmed that the transmitted carrier-suppressed return-to-zero optical signal's carrier phase-relation was held.

The Another Solution Problem (ASP) of a problem is the following problem: for a given instance x of and a solution s to it, find a solution to x other than s. The notion of ASP as a new class of problems was first introduced by Ueda and Nagao. They also pointed out that parsimonious reductions which allow polynomial-time transformation of solutions can derive the NP-completeness of ASP of a certain problem from that of ASP of another. In this paper we consider n-ASP, the problem to find another solution when n solutions are given, and formalize it to investigate its characteristics. In particular we consider ASP-completeness, the completeness with respect to the reductions satisfying the properties mentioned above. The complexity of ASPs has a relation with the difficulty of designing puzzles. We prove the ASP-completeness of three popular puzzles: Slither Link, Cross Sum, and Number Place. Since ASP-completeness implies NP-completeness, these results can be regarded as new results of NP-completeness proof of puzzles.

This paper presents an innovative 155Mb/s burst-mode laser transmitter chip, which was designed and successfully demonstrated, and contains several new subsystems: a digitally programmed current source, programmable up to 120mA with a resolution of 0.1mA, a fast but accurate intermittent optical level monitoring circuit, and a digital Automatic Power Control (APC) algorithm. This generic and intelligent chip was developed in a standard digital 0.35µm CMOS process. Extensive testing showed a high yield and algorithm stability, as well as excellent performance. During initialization, when the transmitter is connected to the Passive Optical Network (PON) for the first time, maximum three Laser Control Fields (LCF) are needed, with a length of 17bytes (0.88microsecond at 155Mb/s), to stabilize the laser output power. In this short time, the chip can regulate the launched optical output power of any FSAN (Full Service Access Network) compliant laser diode to the required level, even in the extreme circumstances caused by outdoor operation or by battery backup operation during power outages. Other tests show that the chip can further stabilize and track this launched optical power with a tolerance lower than 1dB over a wide temperature range, during the burst mode data transmission. The APC algorithm intermittently adjusts the optical power to be transmitted in a digital way, starting from loosely specified but safe preset values, to the required stable logic "1" and "0" level. No laborious calibration of the laser characteristic curve and storage of the calibration values in lookup tables are needed, nor any off-chip adjustable component. The power consumption is significantly reduced by disabling inactive circuitry and by gating the digital high-speed clock. Although this laser transmitter was developed for FSAN PON applications, which are standardized at a speed of 155Mb/s upstream, the design concept is quite generic and can be applied for developing a wide range of burst mode laser transmitters, such as required for Gigabit PON systems or other TDMA networks.

This paper describes the realization of a dynamically reconfigurable logic LSI based on a novel parallel computer architecture. The key point of the architecture is its dual-structured cell array which enables dynamic and autonomous reconfiguration of the logic circuits. The LSI was completed by successfully introducing two specific features: fully asynchronous logic circuits and a homogeneous structure, only LUTs are used.

Burst switched WDM optical networks are coming up as suitable network architectures for future Optical Internet backbones. However, the lack of optical processing capabilities results in increased burst blocking probability, which in turn lead to very limited network performance. Efficient contention resolution algorithm is therefore necessary. In this paper, we propose a distributed wavelength assignment algorithm named Priority-based Wavelength Assignment (PWA) for such networks. Each node selectively assigns wavelengths based on the wavelength priority information "learned" from its wavelength utilization history in a distributed manner. As the learning process progresses, nodes in the same part of the network tend to assign different wavelengths to avoid contentions. Simulation results show that the PWA can effectively reduce the blocking probability and increase the performance of burst optical networks compared to previous algorithms such as random assignment.

Wavelength conversion using the cross-gain modulation (XGM) of amplified spontaneous emission (ASE) in a traveling-wave type semiconductor optical amplifier (TW-SOA) is theoretically studied. Taking into account the spatial and temporal variations of carrier density along the SOA length, output signal and converted ASE waveforms are analyzed. We also reveal the dependency of the signal and converted ASE waveforms on input signal power and repetition frequency, and confirm that numerical analyses well agree with the experimental results. Finally we qualitatively clarify the way to improve frequency response by simulating eye-diagrams for long SOAs and assist light pumping for the first time.

This paper presents a new reconfigurable hardware paradigm, called evolvable hardware (EHW), and its application to the biomedical engineering problem of an artificial hand controller. Evolvable hardware is based on the idea of combining a reconfigurable hardware device with an artificial intelligence robust search technique called genetic algorithms (GAs) to execute reconfiguration autonomously. The first version of the EHW chip was designed in 1998, and this paper describes the latest improvements to the EHW chip, as well as outlining its architecture and the hardware implementation of the GA operations. Execution speed for genetic operations is shown to be about 38.7 times faster with the hardware implementation than with software program running on an AMD Athlon processor (1.2GHz). As an application of the EHW chip, this paper introduces a controller for a multi-functional prosthetic-hand, and presents experimental data in which a practical myoelectric pattern classification rate of 97.8% was achieved through the application of the EHW chip.

A new algorithm for efficient arithmetic in an optimal extension field is proposed. The new algorithm improves the speeds of multiplication, squaring, and inversion by performing two subfield multiplications simultaneously within a single integer multiplication instruction of a CPU. Our algorithm is used to improve throughputs of elliptic curve operations.

This paper presents an efficient application of hot-carrier reliability simulation to delay libraries of 0.18µm and 0.14µm gate length logic products. Using analysis of simple primitive inverter cells, a design rule was developed in restricting signal rise time, and delay libraries of actual products were screened to check whether the rise time restrictions were met. At 200MHz, maximum rise time (0-100%) triseMAX was 0.8nsec (17% of duty) under Δtd/td = 5%. For a 800,000 net product, only 25 simulations were done (each less than one minute CPU time) for the internal devices with screening done for this logic process. 30 nets were caught, but judged reliable due to their reduced duty.

We propose a coordinated resource allocation (CRA) scheme that can be used to allocate high data-rate users in sectorized cells. This scheme is useful for allocating high data-rate users at cell boundaries. In order to analyze the performance of the proposed scheme, we make an interference model for a sectorized CDMA system and suggest the system load measurement of the forward link. Based on this system load measurement, data throughput for the CDMA system under perfect and imperfect power control is then analyzed. Numerical results show that throughput is significantly increased when the CRA scheme is used.

The c-Secure CRT code is a collusion-secure fingerprinting code whose code length is reduced by using the Chinese Remainder Theorem. The tracing algorithm for the c-secure CRT code drops its performance of traitor tracing when random errors are added to the codewords. In this paper, we show two approaches to enhance random-error-resilience to the tracing algorithm of the c-secure CRT code. The first approach is introducing thresholds for the distinction of the detected part of the embedded data called detected blocks. We propose a method to derive appropriate values of the thresholds on an assumption that the tracer can estimate the random error rate. This modification extends the capability of traitor tracing to the attacks in which the alteration rate of the detected blocks is not fixed to 0.5. The second approach is extending the scope of the search for the detected blocks. With numerical results by computer simulations, we confirmed an impressive improvement of random-error-resilience of a c-secure CRT code.

In 1991 Girault proposed a key agreement protocol based on his new idea of self-certified public key. Later Rueppel and Oorschot showed variants of the Girault scheme. All of these key agreement protocols inherit positive features of self-certified public key so that they can provide higher security and smaller communication overhead than key agreement protocols not based on self-certified public key. Even with such novel features, rigorous security of these protocols has not been made clear yet. In this paper, we give rigorous security analysis of the original and variants of Girault key agreement protocol under several kinds of active attacker models. In particular we show that protocols are either insecure or proven as secure as the Diffie-Hellman problem over Zn with respect to the reduction among functions of computing them. Analyzed protocols include a new variant of 1-pass protocol. As opposed to the original 1-pass protocol, the new variant provides mutual implicit key authentication without increasing the number of passes.

In this paper, we propose a new computer-aided diagnosis system which can extract specific features from hematoxylin and eosin (HE)-stained breast tumor images and evaluate the type of tumor using artificial organisms. The gene of the artificial organisms is defined by three kinds of texture features, which can evaluate the specific features of the tumor region in the image. The artificial organisms move around in the image and investigate their environmental conditions during the searching process. When the target pixel is regarded as a tumor region, the organism obtains energy and produces offspring; organisms in other regions lose energy and die. The searching process is iterated until the 30th generation; as a result, tumor regions are filled with artificial organisms. Whether the detected tumor is benign or malignant is evaluated based on the combination of selected genes. The method developed was applied to 27 test cases and the distinction between benign and malignant tumors by the artificial organisms was successful in about 90% of tumor images. In this diagnosis support system, the combination of genes, which represents specific features of detected tumor region, is selected automatically for each tumor image during the searching process.

A new device structure for electrooptic tunable wavelength filter is reported. Finger electrode electrooptic mode converters are placed on an optical waveguide. The drive voltage amplitude is changed along the propagation distance with a sinusoidal function. Changing the spatial period of sinusoidal voltage results in wavelength tuning. Structure uses interleaved mode converter groups generating cosine and sine function mode conversion strengths.

To an extremely difficult problem of finding the maximum likelihood estimates in a specific mixture regression model, a combination of several optimization techniques is found to be useful. These algorithms are the continuation method, Newton-Raphson method, and simplex method. The simplex method searches for an approximate solution in a wider range of the parameter space, then a combination of the continuation method and the Newton-Raphson method finds a more accurate solution. In this paper, this combination method is applied to find the maximum likelihood estimates in a Weibull-power-law type regression model.

Real traffic flows are captured in various network environments and their statistical properties are analyzed. Based on real traffic flows, MWM (Multifractal Wavelet Model) and Poisson equivalent synthetic traffic flows are generated. Performance analysis of a SB (Synchronous Bulk) packet switch is joined with different types of traffic. Maximum throughput performance of the SB packet switch for various real traffic flows and appropriate MWM and Poisson equivalent synthetic traffic flows are evaluated by using discrete-event simulations. Different flow persistence, SF (Stretch Factor) and scheduling mechanisms are used in order to asses their influence on SB packet switch performance. Traffic asymmetry, either input or output based, has a major influence on SB packet switch performance. By increasing the level of asymmetry, maximum throughput values decrease considerably, especially if the ROT (Rotation) scheduling mechanism is applied. Traffic asymmetry also decreases the influence of the SF parameter on maximum switch throughput. As a general rule of thumb, SF values of no more then 5 must be used if asymmetrical traffic is switched. It is also advisable that OPF (Oldest Packet First) scheduling mechanism is used in such cases. The influence of burstiness and scaling of traffic flows turns out to be relatively insignificant for the SB packet switch maximum throughput results, if the OPF scheduling mechanism is used. Larger throughput discrepancies are detected, if ROT scheduling is used.

This paper investigates the accepting powers of deterministic, Las Vegas, self-verifying nondeterministic, and nondeterministic one-way multi-counter automata with time-bounds. We show that (1) for each k1, there is a language accepted by a Las Vegas one-way k-counter automaton operating in real time, but not accepted by any deterministic one-way k-counter automaton operating in linear time, (2) there is a language accepted by a self-verifying nondeterministic one-way 2-counter automaton operating in real time, but not accepted by any Las Vegas one-way multi-counter automaton operating in polynomial time, (3) there is a language accepted by a self-verifying nondeterministic one-way 1-counter automaton operating in real time, but not accepted by any deterministic one-way multi-counter automaton operating in polynomial time, and (4) there is a language accepted by a nondeterministic one-way 1-counter automaton operating in real time, but not accepted by any self-verifying nondeterministic one-way multi-counter automaton operating in polynomial time.

Online profiling methodologies are studied for exploiting dynamic optimization. On a dynamic optimizable system with online profilers, it has to get accurate profile in early step of the program execution for effective execution. However, for getting more effective profile by online profiling, it has to satisfy "Rapidness" and "Accuracy". They are conflicted requirements. Therefore, it has to choose trade-off point at implementation. We focused into online Hot Instruction Sequence (HIS) profiler to exploit reconfigurable functional units. To circumstantiate the effectiveness of online HIS profiling, we build some evaluation models for experimental evaluation. Our profiler models are SC/DM, SC/FA and JC/DM. These models have different policy of event counting and table lookup. Our event counting policies are simple-counting or jumble-counting. On the other hand, table lookup policies are direct-map or full-associative. In our experimental evaluation, SC/FA and JC/DM models scored higher accuracy than SC/DM. The JC/DM model is able to implement by lower cost for table lookup, but it scored high accuracy comparable to SC/FA.