为了评估Piccolo密码算法的功耗分析安全性,该文提出一种针对Piccolo末轮的攻击模型,基于SASEBO(Side-channel Attack Standard Evaluation BOard)实测功耗数据对该算法进行了相关性功耗分析攻击。针对Piccolo末轮运算中包含白化密钥的...为了评估Piccolo密码算法的功耗分析安全性,该文提出一种针对Piccolo末轮的攻击模型,基于SASEBO(Side-channel Attack Standard Evaluation BOard)实测功耗数据对该算法进行了相关性功耗分析攻击。针对Piccolo末轮运算中包含白化密钥的特点,将末轮攻击密钥(包括轮密钥RK24L,RK24R,WK2,WK3)分成4段子密钥,逐个完成各个子密钥的攻击,使80位种子密钥的搜索空间从280降低到(2×220+2×212+216),使种子密钥的恢复成为可能。攻击结果表明,在实测功耗数据情况下,3000条功耗曲线即可恢复80位种子密钥,证实了该攻击模型的有效性和Piccolo硬件面向功耗分析的脆弱性,研究并采取切实有效的防护措施势在必行。展开更多
A simple channel estimator for space-time coded orthogonal frequency division multiplexing (OFDM) systems in rapid fading channels is proposed. The channels at the training bauds are estimated using the EM (expectatio...A simple channel estimator for space-time coded orthogonal frequency division multiplexing (OFDM) systems in rapid fading channels is proposed. The channels at the training bauds are estimated using the EM (expectation-maximization) algorithm, while the channels at the data bauds are estimated based on the method for modelling the time-varying channel as the linear combination of several time-invariant " Doppler channels". Computer simulations showed that this estimator outperforms the decision-directed tracking in rapid fading channels and that the performance of this method can be improved by iteration.展开更多
New training sequences and frame structure are proposed to estimate time-varying channel for multi-pie-input multiple-output and orthogonal frequency division multiplexing (MIMO-OFDM) systems.Thetraining sequences are...New training sequences and frame structure are proposed to estimate time-varying channel for multi-pie-input multiple-output and orthogonal frequency division multiplexing (MIMO-OFDM) systems.Thetraining sequences are modulatable orthogonal polyphase sequences,which have both good autocorrela-tions and cross-correlations.The channel impulse response (CIR) can be obtained by measuring the cor-relation between the received training sequence and the locally generated training sequence.The trainingsequences are used as guard interval instead of cyclic prefix,which not only improve the transmission ef-ficiency but also enable the channel estimator to track time-varying channel.The simulation results showthat the proposed method has about 2dB SNR gain over conventional methods in fast time-varying chan-nel.展开更多
文摘为了评估Piccolo密码算法的功耗分析安全性,该文提出一种针对Piccolo末轮的攻击模型,基于SASEBO(Side-channel Attack Standard Evaluation BOard)实测功耗数据对该算法进行了相关性功耗分析攻击。针对Piccolo末轮运算中包含白化密钥的特点,将末轮攻击密钥(包括轮密钥RK24L,RK24R,WK2,WK3)分成4段子密钥,逐个完成各个子密钥的攻击,使80位种子密钥的搜索空间从280降低到(2×220+2×212+216),使种子密钥的恢复成为可能。攻击结果表明,在实测功耗数据情况下,3000条功耗曲线即可恢复80位种子密钥,证实了该攻击模型的有效性和Piccolo硬件面向功耗分析的脆弱性,研究并采取切实有效的防护措施势在必行。
文摘A simple channel estimator for space-time coded orthogonal frequency division multiplexing (OFDM) systems in rapid fading channels is proposed. The channels at the training bauds are estimated using the EM (expectation-maximization) algorithm, while the channels at the data bauds are estimated based on the method for modelling the time-varying channel as the linear combination of several time-invariant " Doppler channels". Computer simulations showed that this estimator outperforms the decision-directed tracking in rapid fading channels and that the performance of this method can be improved by iteration.
基金the National High Technology Research and Development Program of China(No.2006AA01Z270)the National Natural Science Foundation of China(No.60332030,60496316)
文摘New training sequences and frame structure are proposed to estimate time-varying channel for multi-pie-input multiple-output and orthogonal frequency division multiplexing (MIMO-OFDM) systems.Thetraining sequences are modulatable orthogonal polyphase sequences,which have both good autocorrela-tions and cross-correlations.The channel impulse response (CIR) can be obtained by measuring the cor-relation between the received training sequence and the locally generated training sequence.The trainingsequences are used as guard interval instead of cyclic prefix,which not only improve the transmission ef-ficiency but also enable the channel estimator to track time-varying channel.The simulation results showthat the proposed method has about 2dB SNR gain over conventional methods in fast time-varying chan-nel.
