A unified architecture of MD5 and RIPEMD-160 hash algorithms

Hash algorithms are important components in many cryptographic applications and security protocol suites. In this paper, a unified architecture for MD5 and RIPEMD-160 hash algorithms is developed. These two algorithms are different in speed and security level. Therefore, a unified hardware design allows applications to switch from one algorithm to another based on different requirements. The architecture has been implemented using Altera's EPF10K50SBC356-1, providing a throughput over 200Mbits/s for MD5 and 80Mbits/s for RIPEMD-160 when operated at 26.66MHz with a resource utilization of 1964LC.published_or_final_versio

Can Performance of Indigenous Factors Influence Growth and Globalisation?"

This paper employs a total of thirty four openness factors and indigenous factors to construct two indicators for 62 world economies for the period 1998-2002. While most globalization studies concentrated on openness factors, regression estimates and simulation studies show that sound performance in indigenous factors are crucial to an economy’s growth and globalization. Empirical evidence shows that an optimal performance in indigenous factors can be identified, and that successful globalized economies are equipped with strong performance in their indigenous factors.Globalization; indigenous factors; openess; world economies

Asymptotically efficient product-limit estimators with censoring indicators missing at random

In this paper, we develop methods for estimating a survival function with censoring indicators missing at random. The resulting methods lead to the use of imputation and inverse probability weighting. We give several asymptotically efficient PL estimators. All the estimators are proved to be strongly uniformly consistent and weakly convergent to a Gaussian process. Further, it is shown that these estimators are asymptotically efficient. A simulation study was carried out to evaluate the finite sample performances of the proposed estimators and compare the proposed estimators with van der Laan and McKeague's (1998) estimator under missing at random (MAR) and missing completely at random (MCAR) assumptions, respectively.published_or_final_versio

Partial-encryption technique for intellectual property protection of FPGA-based products

The configuration-data sequence of a field-programmable gate array (FPGA) is an intellectual property (IP) of the original designer. This paper proposes a partial-encryption (PE) technique for IP protection of configuration-data sequences by means of increasing the reverse-engineering cost. The PE technique encrypts a few selected data of the sequence. These data are selected in a judicious way such that, when a rival competitor copies the partially encrypted sequence into a cloned product, the cloned product performs the expected task to a certain degree of correctness but not absolutely error-free. Debugging is required. It is shown that, without an initial knowledge that a reverse-engineering countermeasure is employed, the PE technique outperforms the full-encryption technique in terms of the reverse-engineering cost. This paper describes implementation details of the proposed PE technique. Issues regarding system designs that embed hidden imperfections are also discussed.published_or_final_versio

Karhunen-Loève expansion of the WSSUS channel output and its application to efficient simulation

This paper derives a Karhunen-Loève (K-L) expansion of the time-varying output of a multipath Rayleigh fading wide-sense-stationary uncorrelated-scattering (WSSUS) channel. It is shown that under the same mean-squared error condition, the number of terms required by the truncated K-L expansion is less than that of the series expansion obtained by using the discrete-path approximation of the channel so that simulation using the K-L expansion is more efficient This computational advantage becomes more significant as higher simulation accuracy is required. The derived K-L expansion is applied to develop an efficient simulation technique for digital transmission over a multipath Rayleigh fading WSSUS channel using an optimum receiver. We show that the proposed technique requires shorter computation time than two other known simulation techniques.published_or_final_versio

Impact of power control and lognormal shadowing on the mean transmit power of Bluetooth devices

This letter analyzes Bluetooth's power-control algorithm with a goal to study the mean transmit power required in the presence of lognormal shadowing. The following results are found. 1) A smaller power-control step size yields a lower mean transmit power. 2) When the standard deviations of lognormal shadowing are 3 and 6 dB, respectively, a Bluetooth device needs to consume 11.1 dB and 15.0 dB more in the transmit energy than the minimum one required in the absence of shadowing. 3) The transmit energy consumption varies by around 6 dB among Bluetooth devices as a result of the ±6 dB tolerance in the Golden Receive Power Range, which has a nominal size of 20 dB.published_or_final_versio

A simulation model for nakagami-m fading channels, m < 1

This paper proposes a mathematical model for simulating a Nakagami-m fading channel, m < 1. It is shown that the m fading process can be expressed as a product of a square-root-beta process and a complex Gaussian process. Extension of the proposed model to simulate correlated diversity channels is also given. Numerical results demonstrate that statistical properties of the samples generated from the proposed model are close to the required ones. Index Terms - Fading channels, HF channels, simulation, stochastic processes. © 2000 IEEE.published_or_final_versio

Effects of carrier frequency accuracy on quasi-synchronous, multicarrier DS-CDMA communications using optimized sequences

It is known that the multiple access interference (MAI) of a quasi-synchronous (QS) multicarrier direct signal code division multiple access (DS-CDMA) system can be substantially reduced by using signature sequences having optimized cross correlation at small shifts around the origin. This paper shows that the time-frequency cross correlation function rather than the usual (time-domain) cross correlation determines the MAI when the system is operated in the presence of carrier frequency offset (CFO), which arises due to the frequency-accuracy limit of the oscillator. Several known sets of sequences having optimized time-domain cross correlation are investigated for their MAI-minimization capabilities in the presence of CFO. It is found that: i) a system using Walsh codes or Suehiro-Hatori polyphase sequences can be driven into outage as a result of significant worst-case MAI and ii) it is possible to minimize the MAI for systems using preferentially phased Gold codes cyclic-shift m-sequences or Lin-Chang sequences only if the product of chip period and maximum frequency deviation is less than around 0.01. Implications of these findings to practical implementation of systems are discussed.published_or_final_versio

Performance sensitivity of quasi-synchronous, multicarrier DS-CDMA systems due to carrier frequency disturbance

The multiple access interference (MAI) of a quasi-synchronous, multicarrier DS-CDMA system can be substantially reduced by using sequences having low crosscorrelation at small shifts around the origin. This paper shows that the time-frequency crosscorrelation rather than the usual (time-domain) crosscorrelation determines the MAI when the system is operated in the presence of carrier frequency offset (CFO) which arises due to frequency-accuracy limit of the oscillator. Analysis on the time-frequency crosscorrelation properties reveals that (i) a system using Walsh codes or Suehiro-Hatori polyphase sequences can be driven into outage in the presence of CFO as a result of significant worst-case MAI, and (ii) it is possible to minimize the MAI for systems using preferentially phased Gold codes, cyclic-shift m-sequences or Lin-Chang sequences only if the product of chip period and maximum frequency deviation is less than around 0.01.published_or_final_versio

A low-complexity multitone-CDMA communication technique

Digital implementation of multitone-(MT-) CDMA systems often involves considerable complexity. Assuming the spreading-sequence length, N, is a multiple of the number of subcarriers, M, this paper proposes a new digital MT-CDMA technique that achieves low-implementation complexity. In particular, for the case of rectangular chip waveform, it is shown that the MT-CDMA technique proposed earlier and the technique proposed in this paper require α + αlog2 αN and 1 + (M/N)log2 M multiplications per chip, respectively, where α ≥ 1 is the number of samples per chip. The reduction in complexity is particularly considerable when N is large.published_or_final_versio