Buffer overflow is the most dangerous attack method that can be exploited. According to the statistics of Computer Emergency Readiness Team （ CERT ）, buffer overflow accounts for 50% of the current software vulnerab...Buffer overflow is the most dangerous attack method that can be exploited. According to the statistics of Computer Emergency Readiness Team （ CERT ）, buffer overflow accounts for 50% of the current software vulnerabilities, and this ratio is going up. Considering a subset of C language, Mini C, this paper presents an abstract machine model that can realire buffer overflow detection, which is based on operation semantic. Thus the research on buffer overflow detection can be built on strict descriptions of operation semantic. Not only the correctness can be assured, but also the system can be realized and extended easily.展开更多
Residue number system （RNS） has received considerable attention since decades before, because it has inherent carry-free and parallel properties in addition, sub- traction, and multiplication operations. For an odd ...Residue number system （RNS） has received considerable attention since decades before, because it has inherent carry-free and parallel properties in addition, sub- traction, and multiplication operations. For an odd moduli set, the fundamental problems in RNS, such as number comparison, sign determination, and overflow detection, can be solved based on parity checking. The paper proposes a parity checking algorithm along with related propositions and the certification based on the celebrated Chinese remainder theory （CRT） and mixed radix conversion （MRC） for the moduli set {2^n-1, 2^n＋1, 2^2n＋1}. The parity checker consists of two modular adders and a carry-look-ahead chain. The hardware implementation requires less area and path delay. Besides, the implementations of number comparison, sign determination, and overflow detection, which are based on this parity checker, are also performed in this paper. And this kind of parity checker can be used as a basic element to design ALUs and DSP module in RNS.展开更多
文摘Buffer overflow is the most dangerous attack method that can be exploited. According to the statistics of Computer Emergency Readiness Team （ CERT ）, buffer overflow accounts for 50% of the current software vulnerabilities, and this ratio is going up. Considering a subset of C language, Mini C, this paper presents an abstract machine model that can realire buffer overflow detection, which is based on operation semantic. Thus the research on buffer overflow detection can be built on strict descriptions of operation semantic. Not only the correctness can be assured, but also the system can be realized and extended easily.
基金the National Natural Science Foundation of China (Grant No.60496313)
文摘Residue number system （RNS） has received considerable attention since decades before, because it has inherent carry-free and parallel properties in addition, sub- traction, and multiplication operations. For an odd moduli set, the fundamental problems in RNS, such as number comparison, sign determination, and overflow detection, can be solved based on parity checking. The paper proposes a parity checking algorithm along with related propositions and the certification based on the celebrated Chinese remainder theory （CRT） and mixed radix conversion （MRC） for the moduli set {2^n-1, 2^n＋1, 2^2n＋1}. The parity checker consists of two modular adders and a carry-look-ahead chain. The hardware implementation requires less area and path delay. Besides, the implementations of number comparison, sign determination, and overflow detection, which are based on this parity checker, are also performed in this paper. And this kind of parity checker can be used as a basic element to design ALUs and DSP module in RNS.
