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Direct p-code acquisition algorithm based on bidirectional overlap technique

Journal of Systems Engineering and Electronics 2014年第4期25卷 538-546页

作者： Ying Xu Lijuan Xu Hong Yuan Ruidan Luo Academy of Opto-Electronics Chinese Academy of Sciences University of Chinese Academy of Sciences

According to the signal-to-noise ratio （SNR） loss of average algorithms in direct p-code acquisition method, this paper analyzes the SNR performance of the overlap average algorithm quantitatively, and derives the relationship of SNR loss with overlap shift value and initial average phase difference in the overlap average algorithm. On this basis, the bidirectional overlap average algorithm based on optimal correlation SNR is proposed. The algorithm maintains SNR consistent in the entire initial average phase difference space, and has a better SNR performance than the overlap average algorithm. The effectiveness of the algorithm is verified by both theoretical analysis and simulation results. The SNR performance of the bidirectional overlap average algorithm is 5 dB better than that of the direct average algorithm, and 2 dB better than that of the overlap average algorithm, which provides the support for direct p-code acquisition in low SNR.

关键词： p-code direct acquisition direct average algorithm,bidirectional overlap algorithm.

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Direct p-code Acquisition Technique based on the Data Resource pool

Direct P-code Acquisition Technique based on the Data Resour...

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International Conference on Industry, Information System and Material Engineering

作者： Wang, Na Zhang, GuoMin Liu, JingXia Hu, BingXin Institute of Sciences PLA University of Science and Technology China Institute of Command Automation PLA University of Science and Technology China

ISBN: (纸本)9783037850275

In GpS system, the p-code can offer higher accuracy and better anti-jamming property than C/A code. However, the direct p-code acquisition is difficult as its long period and high chip rate. To solve the problem, the idea of expanding the code sequence to a three-dimensional space is put forward. The concept of data resource pool is defined, and the fast direct p code acquisition technique based on the data resource pool is proposed to improve the acquisition efficiency. By effect compression, the acquisition technique can enlarge the uncertainty search coverage and accelerate the search process. Furthermore, the technique based on the data resource pool can get different sub-algorithms according to the different compression method. The simulation results show that the proposed technique can achieve fast direct p code acquisition by the reasonable choice of compression parameters and the compression mode of code sequence.

关键词： code acquisition p-code Data resource pool Correlation peak

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A Formal Semantics for p-code 1

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14th International Working Conference on Verified Software - Theories, Tools and Experiments (VSTTE)

作者： Naus, Nico Verbeek, Freek Walker, Dale Ravindran, Binoy Virginia Tech Blacksburg VA 24061 USA Open Univ Netherlands Heerlen Netherlands

ISBN: (数字)9783031258039

ISBN: (纸本)9783031258022;9783031258039

Decompilation is currently a widely used tool in reverse engineering and exploit detection in binaries. Ghidra, developed by the National Security Agency, is one of the most popular decompilers. It decompiles binaries to high p-code, from which the final decompilation output in C code is generated. Ghidra allows users to work with p-code, so users can analyze the intermediate representation directly. Several projects make use of this to build tools that perform verification, decompilation, taint analysis and emulation, to name a few. p-code lacks a formal semantics, and its documentation is limited. It has a notoriously subtle semantics, which makes it hard to do any sort of analysis on p-code. We show that p-code, as-is, cannot be given an executable semantics. In this paper, we augment p-code and define a complete, executable, formal semantics for it. This is done by looking at the documentation and the decompilation results of binaries with known source code. The development of a formal p-code semantics uncovered several issues in Ghidra, p-code, and the documentation. We show that these issues affect projects that rely on Ghidra and p-code. We evaluate the executability of our semantics by building a p-code interpreter that directly uses our semantics. Our work uncovered several issues in Ghidra and allows Ghidra users to better leverage p-code.

关键词： Decompilation p-code Formal semantics

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Cdc :: Cyber :: Lang :: Cybil :: 60461290A Cybil p-code Reference Jul84

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2016年

Cdc :: Cyber :: Lang :: Cybil :: 60461290A Cybil p-code Reference Jul84 by published by

关键词： 60461290a actual parameter adaptable adaptable type bound variant compile time cyber cybil expression formal parameter formal parameters format integer integer expression jul84 parameter p-code pointer statement statement list storage management type types variable variant record

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Stanford :: Sel Techreports :: Tn164 a pascal p-code Interpreter for the Stanford Emmy Sep79

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2016年

Stanford :: Sel Techreports :: Tn164 a pascal p-code Interpreter for the Stanford Emmy Sep79 by published by

关键词： address top buffer buffer address buffer variable data segment emmy file file buffer interpreter mark stack ntop pascal pascal programs p-code pop pop integer pop real program push push ntop sep79 stack stanford techreports top

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Stanford :: Sel Techreports :: Tn148 p-code Asmlang pail-4 Mar78

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2016年

Stanford :: Sel Techreports :: Tn148 p-code Asmlang pail-4 Mar78 by published by

关键词： address adr adr adr asmlang assembler assembler language file file address instruction integer intermediate assembler mar78 opcode class pail-4 parameter pascal compiler p-code pushes second parameter stack stanford static level storage units top top item

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Dtca3Doc-151 pascal Grafdemo p-code

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2016年

Dtca3Doc-151 pascal Grafdemo p-code by published by

关键词： apple apple iii cgp cgp erase cgp stuff cgp wait craig grafdemo csp iocheck cxp dtca3doc-151 grafdemo iii computer lao lao nop ldci lsa lsa stuff nop nop cgp pascal p-code sldc sldo

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p—code技术机制剖析

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微型计算机 1995年第6期15卷 70-72页

作者：于长云边奠英

Ｐ－Ｃｏｄｅ是一种新型软件技术，它可以大大缩减ＤＯＳ和Ｗｉｎｄｏｗｓ下可执行文件的尺寸，文章全面剖析了Ｐ－Ｃｏｄｅ技术的内部机理并简明介绍了其应用方法。

关键词： p-code 操作系统可执行文件

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STUDY OF GpS p-code DIRECT ACQUISITION TECHNIQUE

STUDY OF GPS P-CODE DIRECT ACQUISITION TECHNIQUE

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2010 3rd IEEE International Conference on Broadband Network & Multimedia Technology(2010年第三届IEEE宽带网络与多媒体国际会议 IC-BNMT 2010)

作者： Huan Cui Baowang Lian School of Electronics and Information Northwestern Ploytechnical University Xi’an 710072 China

As the typical CDMA application, the spread spectrum pRN codes in GpS are C/A code applied to standard positioning service and p code applied to precise positioning service presently. p code has a higher tolerance to jamming and spoofing compared with the C/A code, C/A code has short length and low data rate, and is vulnerable to interference and spoofing, but p code is usually acquired depending on C/A code. In order to achieve the higher spectrum-spread gain, the better anti-deception and anti-spoofing, p-code direct acquisition should be implemented. A new p code direct acquisition algorithm is proposed by combining the advantages of classical direct acquisition algorithms such as XFAST (Extended Replica Folding Acquisition Search Technique) and average method, and its validity is shown by a simulation experiment. The results show that the algorithm has better acquisition efficiency than XFAST and average method.

关键词： p-code direct acquisition XFAST average method

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指针分析技术驱动的物联网漏洞挖掘方法

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软件导刊 2025年第3期24卷 109-118页

作者：时启亮沙乐天潘家晔南京邮电大学计算机学院江苏省无线传感网高技术研究重点实验室江苏南京210023

物联网漏洞挖掘主要面向源码未知的二进制程序,但存在大量人工审计工作,迫切需要一种高度自动化的流程来进行引导。在静态分析技术领域,指针分析作为一项底层技术,以其高度自动化的分析流程和出色的效果展现出适应多种应用场景的潜力。... 详细信息

物联网漏洞挖掘主要面向源码未知的二进制程序,但存在大量人工审计工作,迫切需要一种高度自动化的流程来进行引导。在静态分析技术领域,指针分析作为一项底层技术,以其高度自动化的分析流程和出色的效果展现出适应多种应用场景的潜力。借助指针分析的优势,依托于反汇编平台Ghidra,对其引入的p-code进行封装形成pIR;以pIR为基础,设计符合漏洞挖掘需求的指针分析算法和污点分析算法,最终实现了一个可扩展的分析框架。针对CWE78漏洞的检测性能测试结果显示,所提框架正确检测出大部分漏洞,与现有漏洞分析工具相比,漏洞检出率提升86.2%,时间效率提升38.7%。该框架不仅能够验证已知漏洞,而且具备发现新漏洞的能力。

关键词：漏洞挖掘 p-code 指针分析污点分析

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