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Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through
deductive reasoning Deductive reasoning is the process of drawing valid inferences. An inference is valid if its conclusion follows logically from its premises, meaning that it is impossible for the premises to be true and the conclusion to be false. For example, t ...
how a previously made device, process, system, or piece of
software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...
accomplishes a task with very little (if any) insight into exactly how it does so. Depending on the system under consideration and the technologies employed, the knowledge gained during reverse engineering can help with repurposing obsolete objects, doing security analysis, or learning how something works. Although the process is specific to the object on which it is being performed, all reverse engineering processes consist of three basic steps: information extraction, modeling, and review. Information extraction is the practice of gathering all relevant information for performing the operation. Modeling is the practice of combining the gathered information into an abstract model, which can be used as a guide for designing the new object or system. Review is the testing of the model to ensure the validity of the chosen abstract. Reverse engineering is applicable in the fields of
computer engineering Computer engineering (CE, CoE, or CpE) is a branch of engineering specialized in developing computer hardware and software. It integrates several fields of electrical engineering, electronics engineering and computer science. Computer engi ...
,
mechanical engineering Mechanical engineering is the study of physical machines and mechanism (engineering), mechanisms that may involve force and movement. It is an engineering branch that combines engineering physics and engineering mathematics, mathematics principl ...
,
design A design is the concept or proposal for an object, process, or system. The word ''design'' refers to something that is or has been intentionally created by a thinking agent, and is sometimes used to refer to the inherent nature of something ...
,
electrical Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...
and electronic engineering,
civil engineering Civil engineering is a regulation and licensure in engineering, professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads ...
, nuclear engineering,
aerospace engineering Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is s ...
,
software engineering Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principl ...
,
chemical engineering Chemical engineering is an engineering field which deals with the study of the operation and design of chemical plants as well as methods of improving production. Chemical engineers develop economical commercial processes to convert raw materials ...
,
systems biology Systems biology is the computational modeling, computational and mathematical analysis and modeling of complex biological systems. It is a biology-based interdisciplinary field of study that focuses on complex interactions within biological system ...
and more.


Overview

There are many reasons for performing reverse engineering in various fields. Reverse engineering has its origins in the analysis of hardware for commercial or military advantage. However, the reverse engineering process may not always be concerned with creating a copy or changing the artifact in some way. It may be used as part of an
analysis Analysis (: analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (38 ...
to deduce design features from products with little or no additional knowledge about the procedures involved in their original production. In some cases, the goal of the reverse engineering process can simply be a redocumentation of
legacy systems Legacy or Legacies may refer to: Arts and entertainment Comics * "Batman: Legacy", a 1996 Batman storyline * ''DC Universe: Legacies'', a comic book series from DC Comics * ''Legacy'', a 1999 quarterly series from Antarctic Press * ''Legacy'', ...
.A Survey of Reverse Engineering and Program Comprehension. Michael L. Nelson, April 19, 1996, ODU CS 551 – Software Engineering Survey. Even when the reverse-engineered product is that of a competitor, the goal may not be to copy it but to perform competitor analysis. Reverse engineering may also be used to create interoperable products and despite some narrowly-tailored United States and European Union legislation, the legality of using specific reverse engineering techniques for that purpose has been hotly contested in courts worldwide for more than two decades.
Software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...
reverse engineering can help to improve the understanding of the underlying source code for the maintenance and improvement of the software, relevant information can be extracted to make a decision for software development and graphical representations of the code can provide alternate views regarding the source code, which can help to detect and fix a
software bug A software bug is a design defect ( bug) in computer software. A computer program with many or serious bugs may be described as ''buggy''. The effects of a software bug range from minor (such as a misspelled word in the user interface) to sev ...
or vulnerability. Frequently, as some software develops, its design information and improvements are often lost over time, but that lost information can usually be recovered with reverse engineering. The process can also help to cut down the time required to understand the source code, thus reducing the overall cost of the software development. Reverse engineering can also help to detect and to eliminate a malicious code written to the software with better code detectors. Reversing a source code can be used to find alternate uses of the source code, such as detecting the unauthorized replication of the source code where it was not intended to be used, or revealing how a competitor's product was built. That process is commonly used for "cracking" software and media to remove their
copy protection Copy protection, also known as content protection, copy prevention and copy restriction, is any measure to enforce copyright by preventing the reproduction of software, films, music, and other media. Copy protection is most commonly found on vid ...
, or to create a possibly-improved copy or even a knockoff, which is usually the goal of a competitor or a hacker.
Malware Malware (a portmanteau of ''malicious software'')Tahir, R. (2018)A study on malware and malware detection techniques . ''International Journal of Education and Management Engineering'', ''8''(2), 20. is any software intentionally designed to caus ...
developers often use reverse engineering techniques to find vulnerabilities in an
operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...
to build a
computer virus A computer virus is a type of malware that, when executed, replicates itself by modifying other computer programs and Code injection, inserting its own Computer language, code into those programs. If this replication succeeds, the affected areas ...
that can exploit the system vulnerabilities. Reverse engineering is also being used in
cryptanalysis Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic se ...
to find vulnerabilities in
substitution cipher In cryptography, a substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the "units" may be single letters (the most common), pairs of letters, t ...
,
symmetric-key algorithm Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between ...
or
public-key cryptography Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic alg ...
. There are other uses to reverse engineering: *Games. Reverse engineering in the context of games and game engines is often used to understand underlying mechanics, data structures, and proprietary protocols, allowing developers to create mods, custom tools, or to enhance compatibility. This practice is particularly useful when interfacing with existing systems to improve interoperability between different game components, engines, or platforms. Platforms lik
Reshax
provide tools and resources that assist in analyzing game binaries, dissecting game engine behavior, thus contributing to a deeper understanding of game technology and enabling community-driven enhancements. * Interfacing. Reverse engineering can be used when a system is required to interface to another system and how both systems would negotiate is to be established. Such requirements typically exist for interoperability. * Military or commercial
espionage Espionage, spying, or intelligence gathering, as a subfield of the intelligence field, is the act of obtaining secret or confidential information ( intelligence). A person who commits espionage on a mission-specific contract is called an ...
. Learning about an enemy's or competitor's latest research by stealing or capturing a prototype and dismantling it may result in the development of a similar product or a better countermeasure against it. * Obsolescence.
Integrated circuits An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...
are often designed on proprietary systems and built on production lines, which become obsolete in only a few years. When systems using those parts can no longer be maintained since the parts are no longer made, the only way to incorporate the functionality into new technology is to reverse-engineer the existing chip and then to redesign it using newer tools by using the understanding gained as a guide. Another obsolescence originated problem that can be solved by reverse engineering is the need to support (maintenance and supply for continuous operation) existing legacy devices that are no longer supported by their original equipment manufacturer. The problem is particularly critical in military operations. * Product security analysis. That examines how a product works by determining the specifications of its components and estimate costs and identifies potential
patent infringement A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...
. Also part of product security analysis is acquiring sensitive data by disassembling and analyzing the design of a system component.Internet Engineering Task Force RFC 2828 Internet Security Glossary Another intent may be to remove
copy protection Copy protection, also known as content protection, copy prevention and copy restriction, is any measure to enforce copyright by preventing the reproduction of software, films, music, and other media. Copy protection is most commonly found on vid ...
or to circumvent access restrictions. * Competitive technical intelligence. That is to understand what one's competitor is actually doing, rather than what it says that it is doing. * Saving money. Finding out what a piece of electronics can do may spare a user from purchasing a separate product. *
Repurposing Repurposing is the process by which an object with one use value is transformed or redeployed as an object with an alternative use value. Description Repurposing is as old as human civilization, with many contemporary scholars investigating ho ...
. Obsolete objects are then reused in a different-but-useful manner. *
Design A design is the concept or proposal for an object, process, or system. The word ''design'' refers to something that is or has been intentionally created by a thinking agent, and is sometimes used to refer to the inherent nature of something ...
. Production and design companies applied Reverse Engineering to practical craft-based manufacturing process. The companies can work on "historical" manufacturing collections through 3D scanning, 3D re-modeling and re-design. In 2013 Italian manufactures Baldi and Savio Firmino together with University of Florence optimized their innovation, design, and production processes.


Common uses


Machines

As
computer-aided design Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve c ...
(CAD) has become more popular, reverse engineering has become a viable method to create a 3D virtual model of an existing physical part for use in 3D CAD,
CAM Cam or CAM may refer to: Science and technology * Cam (mechanism), a mechanical linkage which translates motion * Camshaft, a shaft with a cam * Camera or webcam, a device that records images or video In computing * Computer-aided manufacturin ...
, CAE, or other
software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...
. The reverse-engineering process involves measuring an object and then reconstructing it as a 3D model. The physical object can be measured using 3D scanning technologies like CMMs, laser scanners, structured light digitizers, or industrial CT scanning (computed tomography). The measured
data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...
alone, usually represented as a
point cloud A point cloud is a discrete set of data Point (geometry), points in space. The points may represent a 3D shape or object. Each point Position (geometry), position has its set of Cartesian coordinates (X, Y, Z). Points may contain data other than ...
, lacks
topological Topology (from the Greek words , and ) is the branch of mathematics concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending; that is, wit ...
information Information is an Abstraction, abstract concept that refers to something which has the power Communication, to inform. At the most fundamental level, it pertains to the Interpretation (philosophy), interpretation (perhaps Interpretation (log ...
and design intent. The former may be recovered by converting the point cloud to a triangular-faced mesh. Reverse engineering aims to go beyond producing such a mesh and to recover the design intent in terms of simple analytical surfaces where appropriate ( planes, cylinders, etc.) as well as possibly NURBS surfaces to produce a boundary-representation CAD model. Recovery of such a model allows a design to be modified to meet new requirements, a manufacturing plan to be generated, etc. Hybrid modeling is a commonly used term when NURBS and parametric modeling are implemented together. Using a combination of geometric and freeform surfaces can provide a powerful method of
3D modeling In 3D computer graphics, 3D modeling is the process of developing a mathematical coordinate-based Computer representation of surfaces, representation of a surface of an object (inanimate or living) in Three-dimensional space, three dimensions vi ...
. Areas of freeform data can be combined with exact geometric surfaces to create a hybrid model. A typical example of this would be the reverse engineering of a cylinder head, which includes freeform cast features, such as water jackets and high-tolerance machined areas. Reverse engineering is also used by businesses to bring existing physical geometry into digital product development environments, to make a digital 3D record of their own products, or to assess competitors' products. It is used to analyze how a product works, what it does, what components it has; estimate costs; identify potential
patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...
infringement; etc.
Value engineering Value engineering (VE) is a systematic analysis of the functions of various components and materials to lower the cost of goods, products and services with a tolerable loss of performance or functionality. Value, as defined, is the ratio of func ...
, a related activity that is also used by businesses, involves deconstructing and analyzing products. However, the objective is to find opportunities for cost-cutting.


Printed circuit boards

Reverse engineering of
printed circuit board A printed circuit board (PCB), also called printed wiring board (PWB), is a Lamination, laminated sandwich structure of electrical conduction, conductive and Insulator (electricity), insulating layers, each with a pattern of traces, planes ...
s involves recreating fabrication data for a particular circuit board. This is done primarily to identify a design, and learn the functional and structural characteristics of a design. It also allows for the discovery of the design principles behind a product, especially if this design information is not easily available. Outdated PCBs are often subject to reverse engineering, especially when they perform highly critical functions such as powering machinery, or other electronic components. Reverse engineering these old parts can allow the reconstruction of the PCB if it performs some crucial task, as well as finding alternatives which provide the same function, or in upgrading the old PCB. Reverse engineering PCBs largely follow the same series of steps. First, images are created by drawing, scanning, or taking photographs of the PCB. Then, these images are ported to suitable reverse engineering software in order to create a rudimentary design for the new PCB. The quality of these images that is necessary for suitable reverse engineering is proportional to the complexity of the PCB itself. More complicated PCBs require well lighted photos on dark backgrounds, while fairly simple PCBs can be recreated simply with just basic dimensioning. Each layer of the PCB is carefully recreated in the software with the intent of producing a final design as close to the initial. Then, the schematics for the circuit are finally generated using an appropriate tool.


Software

In 1990, the
Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines. The IEEE has a corporate office ...
(IEEE) defined (software) reverse engineering (SRE) as "the process of analyzing a subject system to identify the system's components and their interrelationships and to create representations of the system in another form or at a higher level of abstraction" in which the "subject system" is the end product of software development. Reverse engineering is a process of examination only, and the software system under consideration is not modified, which would otherwise be re-engineering or restructuring. Reverse engineering can be performed from any stage of the product cycle, not necessarily from the functional end product. There are two components in reverse engineering: redocumentation and design recovery. Redocumentation is the creation of new representation of the computer code so that it is easier to understand. Meanwhile, design recovery is the use of deduction or reasoning from general knowledge or personal experience of the product to understand the product's functionality fully. It can also be seen as "going backwards through the development cycle". In this model, the output of the implementation phase (in source code form) is reverse-engineered back to the analysis phase, in an inversion of the traditional waterfall model. Another term for this technique is program comprehension. The Working Conference on Reverse Engineering (WCRE) has been held yearly to explore and expand the techniques of reverse engineering.
Computer-aided software engineering Computer-aided software engineering (CASE) is a domain of software tools used to design and implement applications. CASE tools are similar to and are partly inspired by computer-aided design (CAD) tools used for designing hardware products. CASE ...
(CASE) and automated code generation have contributed greatly in the field of reverse engineering. Software anti-tamper technology like
obfuscation Obfuscation is the obscuring of the intended meaning of communication by making the message difficult to understand, usually with confusing and ambiguous language. The obfuscation might be either unintentional or intentional (although intent ...
is used to deter both reverse engineering and re-engineering of proprietary software and software-powered systems. In practice, two main types of reverse engineering emerge. In the first case, source code is already available for the software, but higher-level aspects of the program, which are perhaps poorly documented or documented but no longer valid, are discovered. In the second case, there is no source code available for the software, and any efforts towards discovering one possible source code for the software are regarded as reverse engineering. The second usage of the term is more familiar to most people. Reverse engineering of software can make use of the clean room design technique to avoid copyright infringement. On a related note, black box testing in
software engineering Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principl ...
has a lot in common with reverse engineering. The tester usually has the
API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...
but has the goals to find bugs and undocumented features by bashing the product from outside. Other purposes of reverse engineering include security auditing, removal of copy protection (" cracking"), circumvention of access restrictions often present in
consumer electronics Consumer electronics, also known as home electronics, are electronic devices intended for everyday household use. Consumer electronics include those used for entertainment, Communication, communications, and recreation. Historically, these prod ...
, customization of
embedded systems An embedded system is a specialized computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is em ...
(such as engine management systems), in-house repairs or retrofits, enabling of additional features on low-cost "crippled" hardware (such as some graphics card chip-sets), or even mere satisfaction of curiosity.


Binary software

Binary reverse engineering is performed if source code for a software is unavailable. This process is sometimes termed ''reverse code engineering'', or RCE. For example, decompilation of binaries for the
Java platform Java is a set of computer software and specifications that provides a software platform for developing application software and deploying it in a cross-platform computing environment. Java is used in a wide variety of computing platforms fr ...
can be accomplished by using Jad. One famous case of reverse engineering was the first non-
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
implementation of the PC
BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization d ...
, which launched the historic
IBM PC compatible An IBM PC compatible is any personal computer that is hardware- and software-compatible with the IBM Personal Computer (IBM PC) and its subsequent models. Like the original IBM PC, an IBM PC–compatible computer uses an x86-based central p ...
industry that has been the overwhelmingly-dominant
computer hardware Computer hardware includes the physical parts of a computer, such as the central processing unit (CPU), random-access memory (RAM), motherboard, computer data storage, graphics card, sound card, and computer case. It includes external devices ...
platform for many years. Reverse engineering of software is protected in the US by the
fair use Fair use is a Legal doctrine, doctrine in United States law that permits limited use of copyrighted material without having to first acquire permission from the copyright holder. Fair use is one of the limitations to copyright intended to bal ...
exception in
copyright law A copyright is a type of intellectual property that gives its owner the exclusive legal right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, e ...
. The Samba software, which allows systems that do not run
Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
systems to share files with systems that run it, is a classic example of software reverse engineering since the Samba project had to reverse-engineer unpublished information about how Windows file sharing worked so that non-Windows computers could emulate it. The
Wine Wine is an alcoholic drink made from Fermentation in winemaking, fermented fruit. Yeast in winemaking, Yeast consumes the sugar in the fruit and converts it to ethanol and carbon dioxide, releasing heat in the process. Wine is most often made f ...
project does the same thing for the
Windows API The Windows API, informally WinAPI, is the foundational application programming interface (API) that allows a computer program to access the features of the Microsoft Windows operating system in which the program is running. Programs can acces ...
, and OpenOffice.org is one party doing that for the Microsoft Office file formats. The
ReactOS ReactOS is a Free and open-source software, free and open-source operating system for i586/amd64 personal computers that is intended to be binary-code compatibility, binary-compatible with computer programs and device drivers developed for Wind ...
project is even more ambitious in its goals by striving to provide binary (ABI and API) compatibility with the current Windows operating systems of the NT branch, which allows software and drivers written for Windows to run on a clean-room reverse-engineered
free software Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...
( GPL) counterpart. WindowsSCOPE allows for reverse-engineering the full contents of a Windows system's live memory including a binary-level, graphical reverse engineering of all running processes.


=Binary software techniques

= Reverse engineering of software can be accomplished by various methods. The three main groups of software reverse engineering are #Analysis through observation of information exchange, most prevalent in protocol reverse engineering, which involves using bus analyzers and packet sniffers, such as for accessing a computer bus or
computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...
connection and revealing the traffic data thereon. Bus or network behavior can then be analyzed to produce a standalone implementation that mimics that behavior. That is especially useful for reverse engineering
device driver In the context of an operating system, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabli ...
s. Sometimes, reverse engineering on
embedded system An embedded system is a specialized computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is e ...
s is greatly assisted by tools deliberately introduced by the manufacturer, such as JTAG ports or other debugging means. In
Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
, low-level debuggers such as SoftICE are popular. # Disassembly using a disassembler, meaning the raw machine language of the program is read and understood in its own terms, only with the aid of machine-language
mnemonic A mnemonic device ( ), memory trick or memory device is any learning technique that aids information retention or retrieval in the human memory, often by associating the information with something that is easier to remember. It makes use of e ...
s. It works on any computer program but can take quite some time, especially for those who are not used to machine code. The Interactive Disassembler is a particularly popular tool. #Decompilation using a
decompiler A decompiler is a computer program that translates an executable file back into high-level source code. Unlike a compiler, which converts high-level code into machine code, a decompiler performs the reverse process. While disassemblers translate e ...
, a process that tries, with varying results, to recreate the source code in some high-level language for a program only available in machine code or
bytecode Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references (normal ...
.


Software classification

Software classification is the process of identifying similarities between different software binaries (such as two different versions of the same binary) used to detect code relations between software samples. The task was traditionally done manually for several reasons (such as patch analysis for vulnerability detection and
copyright infringement Copyright infringement (at times referred to as piracy) is the use of Copyright#Scope, works protected by copyright without permission for a usage where such permission is required, thereby infringing certain exclusive rights granted to the c ...
), but it can now be done somewhat automatically for large numbers of samples. This method is being used mostly for long and thorough reverse engineering tasks (complete analysis of a complex algorithm or big piece of software). In general,
statistical classification When classification is performed by a computer, statistical methods are normally used to develop the algorithm. Often, the individual observations are analyzed into a set of quantifiable properties, known variously as explanatory variables or ''f ...
is considered to be a hard problem, which is also true for software classification, and so few solutions/tools that handle this task well.


Source code

A number of UML tools refer to the process of importing and analysing source code to generate UML diagrams as "reverse engineering". See List of UML tools. Although UML is one approach in providing "reverse engineering" more recent advances in international standards activities have resulted in the development of the Knowledge Discovery Metamodel (KDM). The standard delivers an ontology for the intermediate (or abstracted) representation of programming language constructs and their interrelationships. An
Object Management Group The Object Management Group (OMG®) is a computer industry Standards Development Organization (SDO), or Voluntary Consensus Standards Body (VCSB). OMG develops enterprise integration and modeling standards for a range of technologies. Busin ...
standard (on its way to becoming an ISO standard as well), KDM has started to take hold in industry with the development of tools and analysis environments that can deliver the extraction and analysis of source, binary, and byte code. For source code analysis, KDM's granular standards' architecture enables the extraction of software system flows (data, control, and call maps), architectures, and business layer knowledge (rules, terms, and process). The standard enables the use of a common data format (XMI) enabling the correlation of the various layers of system knowledge for either detailed analysis (such as root cause, impact) or derived analysis (such as business process extraction). Although efforts to represent language constructs can be never-ending because of the number of languages, the continuous evolution of software languages, and the development of new languages, the standard does allow for the use of extensions to support the broad language set as well as evolution. KDM is compatible with UML, BPMN, RDF, and other standards enabling migration into other environments and thus leverage system knowledge for efforts such as software system transformation and enterprise business layer analysis.


Protocols

Protocols are sets of rules that describe message formats and how messages are exchanged: the protocol state machine. Accordingly, the problem of protocol reverse-engineering can be partitioned into two subproblems: message format and state-machine reverse-engineering. The message formats have traditionally been reverse-engineered by a tedious manual process, which involved analysis of how protocol implementations process messages, but recent research proposed a number of automatic solutions.P. M. Comparetti, G. Wondracek, C. Kruegel, and E. Kirda. Prospex: Protocol specification extraction. In Proceedings of the 2009 30th IEEE Symposium on Security and Privacy, pp. 110–125, Washington, 2009. IEEE Computer Society. Typically, the automatic approaches group observe messages into clusters by using various clustering analyses, or they emulate the protocol implementation tracing the message processing. There has been less work on reverse-engineering of state-machines of protocols. In general, the protocol state-machines can be learned either through a process of offline learning, which passively observes communication and attempts to build the most general state-machine accepting all observed sequences of messages, and online learning, which allows interactive generation of probing sequences of messages and listening to responses to those probing sequences. In general, offline learning of small state-machines is known to be
NP-complete In computational complexity theory, NP-complete problems are the hardest of the problems to which ''solutions'' can be verified ''quickly''. Somewhat more precisely, a problem is NP-complete when: # It is a decision problem, meaning that for any ...
, but online learning can be done in polynomial time. An automatic offline approach has been demonstrated by Comparetti et al. and an online approach by Cho et al. Other components of typical protocols, like encryption and hash functions, can be reverse-engineered automatically as well. Typically, the automatic approaches trace the execution of protocol implementations and try to detect buffers in memory holding unencrypted packets.


Integrated circuits/smart cards

Reverse engineering is an invasive and destructive form of analyzing a
smart card A smart card (SC), chip card, or integrated circuit card (ICC or IC card), is a card used to control access to a resource. It is typically a plastic credit card-sized card with an Embedded system, embedded integrated circuit (IC) chip. Many smart ...
. The attacker uses chemicals to etch away layer after layer of the smart card and takes pictures with a
scanning electron microscope A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that ...
(SEM). That technique can reveal the complete hardware and software part of the smart card. The major problem for the attacker is to bring everything into the right order to find out how everything works. The makers of the card try to hide keys and operations by mixing up memory positions, such as by bus scrambling. In some cases, it is even possible to attach a probe to measure voltages while the smart card is still operational. The makers of the card employ sensors to detect and prevent that attack. That attack is not very common because it requires both a large investment in effort and special equipment that is generally available only to large chip manufacturers. Furthermore, the payoff from this attack is low since other security techniques are often used such as shadow accounts. It is still uncertain whether attacks against chip-and-PIN cards to replicate encryption data and then to crack PINs would provide a cost-effective attack on multifactor authentication. Full reverse engineering proceeds in several major steps. The first step after images have been taken with a SEM is stitching the images together, which is necessary because each layer cannot be captured by a single shot. A SEM needs to sweep across the area of the circuit and take several hundred images to cover the entire layer. Image stitching takes as input several hundred pictures and outputs a single properly-overlapped picture of the complete layer. Next, the stitched layers need to be aligned because the sample, after etching, cannot be put into the exact same position relative to the SEM each time. Therefore, the stitched versions will not overlap in the correct fashion, as on the real circuit. Usually, three corresponding points are selected, and a transformation applied on the basis of that. To extract the circuit structure, the aligned, stitched images need to be segmented, which highlights the important circuitry and separates it from the uninteresting background and insulating materials. Finally, the wires can be traced from one layer to the next, and the netlist of the circuit, which contains all of the circuit's information, can be reconstructed.


Military applications

Reverse engineering is often used by people to copy other nations' technologies, devices, or information that have been obtained by regular troops in the fields or by
intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. It can be described as t ...
operations. It was often used during the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
and the
Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
. Here are well-known examples from the Second World War and later: * Jerry can: British and American forces in WW2 noticed that the Germans had gasoline cans with an excellent design. They reverse-engineered copies of those cans, which were popularly known as "Jerry cans". * Nakajima G5N: In 1939, the U.S. Douglas Aircraft Company sold its DC-4E airliner prototype to Imperial Japanese Airways, which was secretly acting as a front for the
Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, Potsdam Declaration, when it was dissolved followin ...
, which wanted a long-range
strategic bomber A strategic bomber is a medium- to long-range Penetrator (aircraft), penetration bomber aircraft designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unl ...
but had been hindered by the Japanese aircraft industry's inexperience with heavy long-range aircraft. The DC-4E was transferred to the Nakajima Aircraft Company and dismantled for study; as a cover story, the Japanese press reported that it had crashed in
Tokyo Bay is a bay located in the southern Kantō region of Japan spanning the coasts of Tokyo, Kanagawa Prefecture, and Chiba Prefecture, on the southern coast of the island of Honshu. Tokyo Bay is connected to the Pacific Ocean by the Uraga Channel. Th ...
. The wings, engines, and
landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for taxiing, takeoff or landing. For aircraft, it is generally needed for all three of these. It was also formerly called ''alighting gear'' by some manufacturers, s ...
of the G5N were copied directly from the DC-4E. * Panzerschreck: The Germans captured an American
bazooka The Bazooka () is a Man-portable anti-tank systems, man-portable recoilless Anti-tank warfare, anti-tank rocket launcher weapon, widely deployed by the United States Army, especially during World War II. Also referred to as the "stovepipe", th ...
during the Second World War and reverse engineered it to create the larger Panzerschreck. * Tupolev Tu-4: In 1944, three American
B-29 The Boeing B-29 Superfortress is a retired American four-engined Propeller (aeronautics), propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to ...
bombers on missions over
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
were forced to land in the
Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
. The Soviets, who did not have a similar strategic bomber, decided to copy the B-29. Within three years, they had developed the Tu-4, a nearly-perfect copy. * SCR-584 radar: copied by the Soviet Union after the Second World War, it is known for a few modifications - СЦР-584, Бинокль-Д. * V-2 rocket: Technical documents for the V-2 and related technologies were captured by the Western Allies at the end of the war. The Americans focused their reverse engineering efforts via Operation Paperclip, which led to the development of the PGM-11 Redstone rocket. The Soviets used captured German engineers to reproduce technical documents and plans and worked from captured hardware to make their clone of the rocket, the R-1. Thus began the postwar Soviet rocket program, which led to the R-7 and the beginning of the
space race The Space Race (, ) was a 20th-century competition between the Cold War rivals, the United States and the Soviet Union, to achieve superior spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between t ...
. * K-13/R-3S missile (
NATO reporting name NATO uses a system of code names, called reporting names, to denote military aircraft and other equipment used by post-Soviet states, former Warsaw Pact countries, China, and other countries. The system assists military communications by providi ...
AA-2 Atoll), a Soviet reverse-engineered copy of the
AIM-9 Sidewinder The AIM-9 Sidewinder is a short-range air-to-air missile. Entering service with the United States Navy in 1956 and the Air Force in 1964, the AIM-9 is one of the oldest, cheapest, and most successful air-to-air missiles. Its latest variants rema ...
, was made possible after a Taiwanese (ROCAF) AIM-9B hit a Chinese PLA MiG-17 without exploding in September 1958. The missile became lodged within the airframe, and the pilot returned to base with what Soviet scientists would describe as a university course in missile development. * Toophan missile: In May 1975, negotiations between Iran and Hughes Missile Systems on co-production of the
BGM-71 TOW The BGM-71 TOW ("Tube-launched, Optically tracked, wire-guided missile, Wire-guided", pronounced ) is an American anti-tank missile. TOW replaced much smaller missiles like the SS.10 and ENTAC, offering roughly twice the effective range, a more ...
and Maverick missiles stalled over disagreements in the pricing structure, the subsequent 1979 revolution ending all plans for such co-production. Iran was later successful in reverse-engineering the missile and now produces its own copy, the Toophan. * China has reverse engineered many examples of Western and Russian hardware, from fighter aircraft to missiles and HMMWV cars, such as the MiG-15,17,19,21 (which became the J-2,5,6,7) and the Su-33 (which became the J-15). * During the Second World War, Polish and British cryptographers studied captured German " Enigma" message encryption machines for weaknesses. Their operation was then simulated on electromechanical devices, "
bombe The bombe () was an Electromechanics, electro-mechanical device used by British cryptologists to help decipher German Enigma machine, Enigma-machine-encrypted secret messages during World War II. The United States Navy, US Navy and United Sta ...
s", which tried all the possible scrambler settings of the "Enigma" machines that helped the breaking of coded messages that had been sent by the Germans. * Also during the Second World War, British scientists analyzed and defeated a series of increasingly-sophisticated radio navigation systems used by the
Luftwaffe The Luftwaffe () was the aerial warfare, aerial-warfare branch of the before and during World War II. German Empire, Germany's military air arms during World War I, the of the Imperial German Army, Imperial Army and the of the Imperial Ge ...
to perform guided bombing missions at night. The British countermeasures to the system were so effective that in some cases, German aircraft were led by signals to land at RAF bases since they believed that they had returned to German territory.


Gene networks

Reverse engineering concepts have been applied to
biology Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, History of life, origin, evolution, and ...
as well, specifically to the task of understanding the structure and function of gene regulatory networks. They regulate almost every aspect of biological behavior and allow cells to carry out physiological processes and responses to perturbations. Understanding the structure and the dynamic behavior of gene networks is therefore one of the paramount challenges of systems biology, with immediate practical repercussions in several applications that are beyond basic research. There are several methods for reverse engineering gene regulatory networks by using molecular biology and data science methods. They have been generally divided into six classes: * Coexpression methods are based on the notion that if two genes exhibit a similar expression profile, they may be related although no causation can be simply inferred from coexpression. * Sequence motif methods analyze gene promoters to find specific
transcription factor In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription (genetics), transcription of genetics, genetic information from DNA to messenger RNA, by binding t ...
binding domains. If a transcription factor is predicted to bind a promoter of a specific gene, a regulatory connection can be hypothesized. *
Chromatin ImmunoPrecipitation Chromatin immunoprecipitation (ChIP) is a type of immunoprecipitation experimental technique used to investigate the interaction between proteins and DNA in the cell. It aims to determine whether specific proteins are associated with specific genom ...
(ChIP) methods investigate the
genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...
-wide profile of DNA binding of chosen transcription factors to infer their downstream gene networks. * Orthology methods transfer gene network knowledge from one species to another. * Literature methods implement text mining and manual research to identify putative or experimentally-proven gene network connections. * Transcriptional complexes methods leverage information on protein-protein interactions between transcription factors, thus extending the concept of gene networks to include transcriptional regulatory complexes. Often, gene network reliability is tested by genetic perturbation experiments followed by dynamic modelling, based on the principle that removing one network node has predictable effects on the functioning of the remaining nodes of the network. Applications of the reverse engineering of gene networks range from understanding mechanisms of plant physiology to the highlighting of new targets for anticancer therapy.


Overlap with patent law

Reverse engineering applies primarily to gaining understanding of a process or artifact in which the manner of its construction, use, or internal processes has not been made clear by its creator.
Patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...
ed items do not of themselves have to be reverse-engineered to be studied, for the essence of a patent is that inventors provide a detailed public disclosure themselves, and in return receive legal protection of the
invention An invention is a unique or novelty (patent), novel machine, device, Method_(patent), method, composition, idea, or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It m ...
that is involved. However, an item produced under one or more patents could also include other technology that is not patented and not disclosed. Indeed, one common motivation of reverse engineering is to determine whether a competitor's product contains
patent infringement A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...
or
copyright infringement Copyright infringement (at times referred to as piracy) is the use of Copyright#Scope, works protected by copyright without permission for a usage where such permission is required, thereby infringing certain exclusive rights granted to the c ...
.


Legality


United States

In the United States, even if an artifact or process is protected by
trade secrets A trade secret is a form of intellectual property (IP) comprising confidential information that is not generally known or readily ascertainable, derives economic value from its secrecy, and is protected by reasonable efforts to maintain its conf ...
, reverse-engineering the artifact or process is often lawful if it has been legitimately obtained. Reverse engineering of
computer software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...
often falls under both
contract law A contract is an agreement that specifies certain legally enforceable rights and obligations pertaining to two or more Party (law), parties. A contract typically involves consent to transfer of goods, Service (economics), services, money, or pr ...
as a
breach of contract Breach of contract is a legal cause of action and a type of civil wrong, in which a binding agreement or bargained-for exchange is not honored by one or more of the parties to the contract by non-performance or interference with the other part ...
as well as any other relevant laws. That is because most end-user license agreements specifically prohibit it, and US courts have ruled that if such terms are present, they override the copyright law that expressly permits it (see '' Bowers v. Baystate Technologies''). According to Section 103(f) of the Digital Millennium Copyright Act
17 U.S.C. § 1201 (f)
, a person in legal possession of a program may reverse-engineer and circumvent its protection if that is necessary to achieve "interoperability", a term that broadly covers other devices and programs that can interact with it, make use of it, and to use and transfer data to and from it in useful ways. A limited exemption exists that allows the knowledge thus gained to be shared and used for interoperability purposes.


European Union

EU Directive 2009/24 on the legal protection of computer programs, which superseded an earlier (1991) directive, governs reverse engineering in countries of the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
.


See also

* * * * * * * * * * * Connectix Virtual Game Station * * * * * * * * * * * * * List of production topics * * * * * * * * * * *


Notes


References


Sources

* * Elvidge, Julia, "Using Reverse Engineering to Discover Patent Infringement," Chipworks, Sept. 2010. Online: http://www.photonics.com/Article.aspx?AID=44063 * * Hausi A. Müller and Holger M. Kienle, "A Small Primer on Software Reverse Engineering," Technical Report, University of Victoria, 17 pages, March 2009. Online: http://holgerkienle.wikispaces.com/file/view/MK-UVic-09.pdf * Heines, Henry, "Determining Infringement by X-Ray Diffraction," ''Chemical Engineering Process'', Jan. 1999 (example of reverse engineering used to detect IP infringement) * * * (introduction to hardware teardowns, including methodology, goals) * * Samuelson, Pamela and Scotchmer, Suzanne, "The Law and Economics of Reverse Engineering," 111 Yale L.J. 1575 (2002). Online: http://people.ischool.berkeley.edu/~pam/papers/l&e%20reveng3.pdf * (xviii+856+vi pages, 3.5"-floppy) Errata: (NB. On general methodology of reverse engineering, applied to mass-market software: a program for exploring DOS, disassembling DOS.) * (pp. 59–188 on general methodology of reverse engineering, applied to mass-market software: examining Windows executables, disassembling Windows, tools for exploring Windows) * Schulman, Andrew, "Hiding in Plain Sight: Using Reverse Engineering to Uncover Software Patent Infringement," ''Intellectual Property Today'', Nov. 2010. Online: http://www.iptoday.com/issues/2010/11/hiding-in-plain-sight-using-reverse-engineering-to-uncover-software-patent-infringement.asp * Schulman, Andrew, "Open to Inspection: Using Reverse Engineering to Uncover Software Prior Art," ''New Matter'' (Calif. State Bar IP Section), Summer 2011 (Part 1); Fall 2011 (Part 2). Online: http://www.SoftwareLitigationConsulting.com * {{DEFAULTSORT:Reverse Engineering Espionage Patent law Industrial engineering Technical intelligence Technological races NP-complete problems Cybersecurity engineering