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Non-Repudiation

  • Primarily used to prevent a member of the organization to deny that an action took place.
    • Examples: Digitally Signed Documents & Auditing System Logs.

Example 1: Non-Repudiation in a Tech Company

Scenario:
Contoso, a software development company, handles various client projects, and they need to ensure accountability across the development lifecycle. Non-repudiation ensures that actions taken by users, such as code commits or document approvals, cannot be denied later.

Implementation of Non-Repudiation:

  1. Digital Signatures for Code Commits:

    • GitHub/GitLab: Developers use digital signatures when committing code to the company’s repositories. These signatures are tied to the developer’s identity and time-stamped.
    • Why: Later, if a bug or vulnerability is discovered in a commit, the developer responsible for that commit cannot deny having made the change. The signed commits provide cryptographic proof of the origin, ensuring non-repudiation.

  2. Email Communication with Clients:

    • Microsoft 365: The company implements email encryption and digital signatures for all sensitive client communications. Each email is signed with the sender’s private key, making it clear who sent the message and ensuring that the email content hasn’t been altered.
    • Why: If a client later claims they did not receive important project information, the digital signature provides undeniable proof that the communication was sent by the company’s representative.

  3. Approval Workflow:

    • Project Management Tool (e.g., Jira): Before deploying code to production, the project manager or lead developer must sign off on the deployment request digitally. This approval is recorded with a timestamp and identity verification.
    • Why: If a deployment causes production issues, the individual who approved the release cannot later deny having approved it, ensuring accountability throughout the process.

Key Benefits of Non-Repudiation:

  • Accountability: Every action in the system is traceable, making it impossible for users to deny actions like code commits or approvals.
  • Legal Protection: In case of disputes with clients or partners, digital signatures provide irrefutable evidence of communication or agreements.
  • Security: Non-repudiation ensures that sensitive actions (e.g., code deployments, financial transactions) are authorized and traceable, preventing fraudulent activities.