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.:13 However, the reverse engineering process in itself is not concerned with creating a copy or changing the artifact in some way; it is only an analysis in order to deduce design features from products with little or no additional knowledge about the procedures involved in their original production.:15 In some cases, the goal of the reverse engineering process can simply be a redocumentation of legacy systems.:15 Even when the product reverse engineered is that of a competitor, the goal may not be to copy them, 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 this purpose has been hotly contested in courts worldwide for more than two decades.
Software 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 in order 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 or vulnerability. Frequently, as some software develops, its design information and improvements are often lost over time, but this lost information can usually be recovered with reverse engineering. This process can also help to cut down the time required to understand the source code, reducing the overall cost of the software development. Reverse engineering can also help to detect and 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 to detect unauthorized replication of the source code where it wasn't intended to be used, or to reveal how a competitors product was built. This process is commonly used for "cracking" software and media to remove their copy protection,:7 or to create a (possibly improved) copy or even a knockoff, which is usually the goal of a competitor or a hacker.:8 Malware developers often use reverse engineering techniques to find vulnerabilities in an operating system (OS), in order build a computer virus that can exploit the system vulnerabilities.:5 Reverse engineering is also being used in cryptanalysis in order to find vulnerabilities in substitution cipher, symmetric-key algorithm or public-key cryptography.:6
- 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. Learning about an enemy’s or competitor’s latest research by stealing or capturing a prototype and dismantling it, which may result in development of similar product, or a better countermeasure against it.
- Obsolescence. Integrated circuits are often designed on proprietary systems, and built on production lines which become obsolete in only a few years. When systems using these 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 redesign it using newer tools, using the understanding gained as a guide. Another obsolescence originated problem which can be solved by reverse engineering is the need to support (maintenance and supply for continuous operation) existing, legacy devices which are no longer supported by their original equipment manufacturer (OEM). This problem is particularly critical in military operations.
- Product security analysis. To examine how a product works, what are specifications of its components, estimate costs and identify potential patent infringement. Acquiring sensitive data by disassembling and analysing the design of a system component. Another intent may be to remove copy protection, or circumvention of access restrictions.
- Competitive technical intelligence. Understand what one's competitor is actually doing, versus what they say they are doing.
- Saving money, when one finds out what a piece of electronics is capable of, it can spare a user from purchase of a separate product.
- Repurposing, when obsolete objects are reused in a different but useful manner.