The System Development Life Cycle (SDLC) is a structured process used to develop information systems with a focus on meeting the project’s objectives while ensuring the integration of security throughout the development process. The SDLC has several stages, each with specific activities and goals. The System Life Cycle (SLC) extends the SDLC by encompassing the entire lifespan of the system, including its ongoing operation and eventual disposal.

Stages of the System Development Life Cycle (SDLC)

1. Project Initiation
   • Activities:
     • Feasibility Study: Assess the technical, financial, and operational feasibility of the project.
     • Cost and Risk Analysis: Estimate costs and evaluate potential risks.
     • Management Approval: Obtain formal approval to proceed with the project.
     • Basic Security Objectives: Define the initial security goals that will guide the project.
   • Purpose: Establish a foundation for the project and ensure alignment with organizational goals.
2. Functional Analysis and Planning
   • Activities:
     • Define Needs and Requirements: Identify what the system must accomplish and the requirements it must meet.
     • Review Proposed Security Controls: Ensure that security measures are planned for and integrated into the system from the beginning.
   • Purpose: Translate business objectives into specific functional and security requirements.
3. System Design Specifications
   • Activities:
     • Develop Detailed Design Specifications: Create detailed blueprints for the system, including architecture, components, and security features.
     • Review Support Documentation: Ensure all documentation supports the design and future maintenance.
     • Examine Security Controls: Validate that security controls are adequately designed and integrated.
   • Purpose: Provide a clear and complete design that will guide system development.
4. Software Development
   • Activities:
     • Programmers Develop Code: Actual coding and software development based on design specifications.
     • Unit Testing: Test individual modules to ensure they work as intended.
     • Prototyping: Create prototypes to refine requirements and design.
     • Verification and Validation: Verify that the system meets design specifications and validate that it meets user needs.
   • Purpose: Build the system according to the specifications and ensure it functions correctly.
5. Acceptance Testing and Implementation
   • Activities:
     • Separation of Duties: Ensure that no single individual controls all key aspects of the process to prevent fraud or error.
     • Security Testing: Test security controls to ensure they are effective.
     • Data Validation and Bounds Checking: Verify that the system correctly processes inputs and handles unexpected data.
     • Certification and Accreditation: Certify that the system meets security and operational requirements, and formally approve it for production use.
     • Release Control: Manage the process of moving the system from development to production.
   • Purpose: Ensure the system is ready for deployment and meets all requirements.

System Life Cycle (SLC)

The SLC encompasses the entire lifespan of the system, beyond just its development.

1. Operations and Maintenance
   • Activities:
     • Release into Production: Deploy the system for actual use.
     • Certification/Accreditation: Continuously monitor and review the system to ensure it maintains compliance with security and operational standards.
     • Ongoing Maintenance: Regular updates, patches, and enhancements to ensure the system continues to meet user needs and security requirements.
   • Purpose: Ensure the system operates smoothly and securely throughout its life.
2. Revisions/Disposal
   • Activities:
     • System Revisions: Update or revise the system as needed to address new requirements or correct issues.
     • System Disposal: Properly decommission the system when it is no longer needed.
     • Sanitization and Destruction of Data: Securely remove and destroy unneeded data to prevent unauthorized access.
   • Purpose: Ensure that when the system is no longer in use, it is properly decommissioned and all sensitive data is securely handled.

Three Basic Components of the SDLC/SLC:

1. People: The stakeholders involved in each phase of the lifecycle, including management, developers, users, and security professionals.
2. Processes: The structured sequence of activities in each phase that guide the development, deployment, and maintenance of the system.
3. Technology: The tools, software, and hardware used throughout the lifecycle to build, operate, maintain, and eventually dispose of the system.

These components ensure that the SDLC/SLC not only delivers a functional system but also one that is secure, compliant, and aligned with the organization’s overall objectives.