Abstraction Levels in Reverse Engineering

Reverse engineering holds a wide range of tasks that can aid to the understanding and modifying software systems. Its main purpose is to identify and recover program requirements and design requirements information from the system. The abstraction is the process of ignoring certain details in order to simplify the problem and facilitate the specification, design and implementation of a system to proceed in step-wise fashion. In software maintenance, the following three levels of reverse engineering abstraction are defined: implementation abstraction, design abstraction, specification abstraction.

In reverse engineering, abstraction levels refer to the different levels of detail or granularity at which the analysis of a software system can be performed. The higher the abstraction level, the more abstract and higher-level the analysis is, and the lower the level of detail. The following are some common abstraction levels used in reverse engineering:

High-level abstraction: At this level, the focus is on the overall architecture and functionality of the software system. This level of abstraction is useful for understanding the system’s high-level design and the interaction between different modules or components. Tools such as flowcharts, UML diagrams, and data flow diagrams can be used to visualize the high-level design of the software system.

Intermediate-level abstraction: At this level, the focus is on the implementation details of the software system. This level of abstraction is useful for understanding the structure and behavior of individual functions or methods in the code. Tools such as decompilers, disassemblers, and code analyzers can be used to extract and analyze the code at the intermediate level.

Low-level abstraction: At this level, the focus is on the machine code or assembly language level of the software system. This level of abstraction is useful for understanding the low-level details of how the software system works, such as memory allocation, register usage, and control flow. Tools such as debuggers, assembly language viewers, and memory dump analyzers can be used to analyze the software system at the low level.

The choice of abstraction level depends on the goals of the reverse engineering process and the information that needs to be extracted from the software system. Higher levels of abstraction are useful for understanding the overall architecture and functionality of the software system, while lower levels of abstraction are useful for understanding the implementation details and low-level behavior of the software system. A combination of different abstraction levels can provide a more complete understanding of the software system.

In reverse engineering, abstraction levels refer to the different levels of detail and complexity that are used to represent a software system, component, or object. The different levels of abstraction are used to simplify the reverse engineering process and make it easier to understand and analyze a system. The most common abstraction levels used in reverse engineering are:

1. High-level abstraction: This level represents the system at a high-level, and typically includes information about the overall architecture and design of the system. It includes diagrams, flowcharts, and other visual representations of the system.
2. Intermediate-level abstraction: This level represents the system at a more detailed level, and typically includes information about the different components and modules of the system. It includes information about the interfaces, data structures, and control flow of the system.
3. Low-level abstraction: This level represents the system at the lowest level, and typically includes information about the assembly or machine code of the system. It includes information about the memory layout, registers, and instructions of the system.

Each abstraction level provides a different perspective on the system, and by using a combination of abstraction levels, reverse engineers can gain a more complete understanding of the system. High-level abstraction provides an overview of the system, intermediate-level abstraction provides more detail about the different components, and low-level abstraction provides the most detailed information about the system.

1. Implementation abstraction – Implementation abstraction is a lowest level of abstraction and at this level the abstraction of the knowledge of the language in which the system is written, the syntax and semantics of language and the hierarchy of system components rather than data structures and algorithms is abstracted.
2. Design abstraction – Design abstraction is the intermediary level of abstraction. This level abstracts how the components are related and control to each other.
3. Specification abstraction – Specification abstraction abstracts the functions by replacing its algorithmic nature with concepts and specific to the application requirements. Reverse Engineering requires detection of low-level implementations and replacing them with their high-level counterparts. The process eventually as a consequence converts to an incremental formation of an overall architecture of the program.

However, High-level counterpart in reverse engineering does not necessarily mean product with higher level of abstraction. If the level of abstraction of resulting product is at the same level as the original system, the operation is commonly known as “re-documentation”. If on the other hand, the resulting product is at a higher level of abstraction, the operation is known as “design recovery” or “specific recovery”.

1. Redocumentation – Re-documentation is the recreation of a sound mathematical or logical structure precise to its requirements using a specification language(set of notations defining the behavior of the system) within the same relative abstraction level that is equivalent to the representation of the original system. This process has 3 purposes/tasks –
   • (i). Reinforcing the understanding of the product by creating alternating views of the system using data flows or control flow diagram from source code.
   • (ii). Updating the system documentation side by side as changes are being made.
   • (iii). Completing the documentation of the newly modified system for future maintenance work on the system.
2. Design Recovery – Design Recovery includes the domain knowledge, external data and deduction to the system to identify and extract meaningful higher-level abstraction beyond those obtained directly by examining the system itself. It leads the system from a low-level of abstraction to higher-level of abstraction. Design recovery recreates abstraction from a combination of code, existing design documentation (if present), personal experience, and knowledge about problem and application domains.The new design that is the recovered design can be used for redeveloping the system by forming a baseline for future system modifications. 
   Different approaches which vary in their focus, can be used to recover these designs. For example, after recovering the design of word search application, it can used in the design of a word search module in a new word editing application.

ADVANTAGES OR DISADVANTAGES:

Advantages of using different abstraction levels in reverse engineering:

1. Simplifies the reverse engineering process: Using different abstraction levels can simplify the reverse engineering process by breaking down a complex system into smaller, more manageable components.
2. Improves understanding of the system: Using different abstraction levels can improve the understanding of a system by providing different perspectives on the system and making it easier to see the overall architecture and design.
3. Helps to identify vulnerabilities: Using different abstraction levels can help to identify vulnerabilities in a system by providing detailed information about the different components and modules of the system.
4. Increases efficiency: Using different abstraction levels can increase the efficiency of the reverse engineering process by allowing reverse engineers to focus on specific components or modules of the system.

Disadvantages of using different abstraction levels in reverse engineering:

1. Requires specialized skills and tools: Using different abstraction levels in reverse engineering requires specialized skills and tools to understand and analyze the different levels of abstraction.
2. Can be time-consuming: Using different abstraction levels in reverse engineering can be time-consuming, as reverse engineers need to analyze the different levels of abstraction separately.
3. Can lead to confusion: Using different abstraction levels in reverse engineering can lead to confusion if the different levels are not clearly defined or if the relationships between different levels are not well understood.
4. Can lead to oversimplification: Using different abstraction levels in reverse engineering can lead to oversimplification if the different levels are not detailed enough, which can make it difficult to understand the system.