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Okay, let's dive into designing a comprehensive document for the Capybara project, focusing on security and architecture.

BUSINESS POSTURE

Business Priorities and Goals:

The Capybara project aims to create a user-friendly, secure, and efficient password manager. Key priorities include:

  • Providing a secure alternative to browser-based password storage and weak password practices.
  • Offering a seamless user experience across multiple devices (implied by the use of Flutter).
  • Building trust with users through transparency (open-source) and robust security measures.
  • Potentially, future monetization through premium features or enterprise versions (this is a common model for password managers, but not explicitly stated in the repository).
  • Minimizing operational overhead through a serverless architecture.

Most Important Business Risks:

  • Data Breach: The most critical risk is a compromise of the user's encrypted password vault. This would severely damage user trust and could have legal and financial repercussions.
  • Loss of User Data: Data loss due to infrastructure failure, bugs, or user error could lead to significant user frustration and churn.
  • Compromise of Encryption Keys: If the keys used to encrypt user data are compromised, the entire security model collapses.
  • Service Unavailability: Since this is a password manager, unavailability can prevent users from accessing critical services, causing significant disruption.
  • Reputational Damage: Any security incident, even a minor one, could significantly harm the project's reputation and adoption rate, especially given the sensitive nature of the data handled.
  • Supply Chain Attacks: Compromise of dependencies or build tools could introduce vulnerabilities.

SECURITY POSTURE

Existing Security Controls (as inferred from the repository):

  • security control: End-to-End Encryption (E2EE): User data is encrypted on the client-side before being sent to the server. This is evident from the use of client-side encryption libraries and the serverless architecture (which implies the server doesn't have access to decryption keys). Implemented in Flutter application.
  • security control: Use of Supabase: Supabase provides built-in security features like Row Level Security (RLS) and PostgreSQL's security model. Implemented in Supabase.
  • security control: Authentication with Supabase Auth: Leverages Supabase's authentication services, which likely include features like password hashing and secure session management. Implemented in Supabase and Flutter application.
  • security control: Open-Source Codebase: Allows for community scrutiny and auditing of the code for vulnerabilities. Implemented in GitHub repository.

Accepted Risks:

  • accepted risk: Reliance on Supabase: The project's security is heavily dependent on the security of Supabase's infrastructure and services. While Supabase is generally reputable, there's an inherent risk in relying on a third-party provider.
  • accepted risk: User Device Security: The security of the user's device (phone, computer) is outside the project's direct control. A compromised device could expose the user's master password or decrypted data.
  • accepted risk: Limited Formal Security Audits: While the code is open-source, there's no mention of formal security audits or penetration testing, which are crucial for identifying subtle vulnerabilities.

Recommended Security Controls (High Priority):

  • security control: Implement a robust key management strategy. This should include secure generation, storage, and rotation of encryption keys. Consider using a Hardware Security Module (HSM) or a dedicated key management service (KMS) if feasible.
  • security control: Conduct regular security audits and penetration testing by independent security experts.
  • security control: Implement a Web Application Firewall (WAF) to protect against common web attacks, even though the backend is serverless. Supabase might offer this, or a separate service could be used.
  • security control: Implement rate limiting and brute-force protection on authentication endpoints to prevent attackers from guessing passwords.
  • security control: Implement comprehensive logging and monitoring to detect and respond to suspicious activity.
  • security control: Establish a vulnerability disclosure program to encourage responsible reporting of security issues.
  • security control: Implement Multi-Factor Authentication (MFA) as an option for users, adding an extra layer of security.

Security Requirements:

  • Authentication:

    • Strong password policies (minimum length, complexity requirements).
    • Secure password hashing (e.g., using Argon2, bcrypt, or scrypt).
    • Protection against brute-force attacks (rate limiting, account lockout).
    • Support for Multi-Factor Authentication (MFA).
    • Secure session management (e.g., using HttpOnly and Secure cookies, short session timeouts).

  • Authorization:

    • Principle of Least Privilege: Users should only have access to the data and functionality they need.
    • Role-Based Access Control (RBAC) if different user roles are introduced in the future.
    • Supabase Row Level Security (RLS) should be meticulously configured to ensure data isolation between users.

  • Input Validation:

    • All user-supplied input (passwords, usernames, etc.) should be strictly validated to prevent injection attacks and other vulnerabilities.
    • Use of parameterized queries or ORMs to prevent SQL injection (relevant for any database interactions).

  • Cryptography:

    • Use of strong, well-vetted encryption algorithms (e.g., AES-256, ChaCha20).
    • Secure generation of random numbers using cryptographically secure pseudorandom number generators (CSPRNGs).
    • Proper implementation of encryption modes (e.g., GCM, CTR with HMAC) to ensure both confidentiality and integrity.
    • Regular review of cryptographic practices to ensure they remain up-to-date with industry best practices.

DESIGN

C4 CONTEXT

graph LR
    subgraph Capybara System
        A[Capybara Password Manager]
    end
    B[User] --> A
    C[Supabase] <-- A
    D[External Websites/Services] <-- B

    style A fill:#f9f,stroke:#333,stroke-width:2px
    style B fill:#ccf,stroke:#333,stroke-width:2px
    style C fill:#ccf,stroke:#333,stroke-width:2px
    style D fill:#ccf,stroke:#333,stroke-width:2px
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Element Descriptions:

  • Element:

    • Name: User
    • Type: Person
    • Description: A person who uses the Capybara Password Manager to store and manage their passwords.
    • Responsibilities:
      • Creating and managing their password vault.
      • Authenticating with the Capybara application.
      • Using the application to access their passwords.
      • Maintaining the security of their own device.
    • Security controls:
      • Strong password for their Capybara account.
      • Potentially using Multi-Factor Authentication (MFA).
      • Keeping their device secure (e.g., using antivirus software, keeping the OS updated).

  • Element:

    • Name: Capybara Password Manager
    • Type: Software System
    • Description: The password management application itself, consisting of a Flutter-based client and a Supabase backend.
    • Responsibilities:
      • Providing a user interface for managing passwords.
      • Encrypting and decrypting user data.
      • Authenticating users.
      • Storing encrypted data securely in Supabase.
      • Synchronizing data across devices (if implemented).
    • Security controls:
      • End-to-End Encryption (E2EE).
      • Supabase Auth for authentication.
      • Supabase Row Level Security (RLS) for data isolation.
      • Input validation.
      • (Recommended) Rate limiting, brute-force protection, MFA.

  • Element:

    • Name: Supabase
    • Type: External System (Backend-as-a-Service)
    • Description: A cloud platform providing database, authentication, and other backend services.
    • Responsibilities:
      • Storing encrypted user data.
      • Providing authentication services.
      • Enforcing Row Level Security (RLS).
      • Providing a secure infrastructure.
    • Security controls:
      • Supabase's built-in security features (RLS, PostgreSQL security).
      • (Assumed) Infrastructure security measures implemented by Supabase.

  • Element:

    • Name: External Websites/Services
    • Type: External System
    • Description: The various websites and online services that users store their passwords for in Capybara.
    • Responsibilities:
      • Authenticating users based on the credentials provided by the user (often retrieved from Capybara).
    • Security controls:
      • These are outside the control of the Capybara project. The security of these services is the responsibility of their respective providers.

C4 CONTAINER

graph LR
    subgraph Capybara Password Manager
        A[Flutter Client] --> B[Supabase API]
        B --> C[Supabase Database]
        B --> D[Supabase Auth]
    end
    style A fill:#f9f,stroke:#333,stroke-width:2px
    style B fill:#ccf,stroke:#333,stroke-width:2px
    style C fill:#ccf,stroke:#333,stroke-width:2px
    style D fill:#ccf,stroke:#333,stroke-width:2px
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Element Descriptions:

  • Element:

    • Name: Flutter Client
    • Type: Mobile App (and potentially Web/Desktop App)
    • Description: The user interface of the Capybara application, built using the Flutter framework.
    • Responsibilities:
      • Rendering the user interface.
      • Handling user input.
      • Performing client-side encryption and decryption.
      • Communicating with the Supabase API.
    • Security controls:
      • End-to-End Encryption (E2EE) implementation.
      • Secure storage of encryption keys (using Flutter's secure storage capabilities).
      • Input validation.

  • Element:

    • Name: Supabase API
    • Type: API
    • Description: The interface provided by Supabase for interacting with the database and authentication services.
    • Responsibilities:
      • Receiving requests from the Flutter client.
      • Authenticating requests.
      • Routing requests to the appropriate Supabase service (database or auth).
    • Security controls:
      • Authentication and authorization checks.
      • (Assumed) Protection against common web attacks (e.g., DDoS, injection).

  • Element:

    • Name: Supabase Database
    • Type: Database (PostgreSQL)
    • Description: The PostgreSQL database hosted on Supabase, used to store encrypted user data.
    • Responsibilities:
      • Storing encrypted password vault data.
      • Enforcing Row Level Security (RLS).
    • Security controls:
      • Supabase Row Level Security (RLS).
      • (Assumed) Database security measures implemented by Supabase (e.g., encryption at rest, access controls).

  • Element:

    • Name: Supabase Auth
    • Type: Authentication Service
    • Description: The authentication service provided by Supabase.
    • Responsibilities:
      • Handling user registration and login.
      • Managing user sessions.
      • Providing authentication tokens.
    • Security controls:
      • Secure password hashing.
      • (Assumed) Protection against common authentication attacks.
      • (Recommended) Support for Multi-Factor Authentication (MFA).

DEPLOYMENT

Possible Deployment Solutions:

  1. Mobile App Stores (iOS and Android): The primary deployment target for the Flutter client.
  2. Web Application (if a web version is built): Could be hosted on Supabase Hosting, Netlify, Vercel, or other static site hosting platforms.
  3. Desktop Application (if a desktop version is built): Could be distributed through app stores or directly as downloadable executables.

Chosen Deployment Solution (for detailed description): Mobile App Stores (iOS and Android)

graph LR
    subgraph Development Environment
        A[Developer Workstation] --> B[Git Repository (GitHub)]
    end
    subgraph Build Environment
        B --> C[CI/CD Pipeline (e.g., GitHub Actions)]
    end
    subgraph Distribution
        C --> D[App Store Connect (iOS)]
        C --> E[Google Play Console (Android)]
    end
    subgraph User Devices
        D --> F[User's iOS Device]
        E --> G[User's Android Device]
    end

    style A fill:#f9f,stroke:#333,stroke-width:2px
    style B fill:#ccf,stroke:#333,stroke-width:2px
    style C fill:#ccf,stroke:#333,stroke-width:2px
    style D fill:#ccf,stroke:#333,stroke-width:2px
    style E fill:#ccf,stroke:#333,stroke-width:2px
    style F fill:#ccf,stroke:#333,stroke-width:2px
    style G fill:#ccf,stroke:#333,stroke-width:2px
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Element Descriptions:

  • Element:

    • Name: Developer Workstation
    • Type: Infrastructure
    • Description: The local machine where developers write and test code.
    • Responsibilities: Code development, local testing, committing code to the repository.
    • Security controls: Secure coding practices, local security measures (e.g., antivirus, firewall).

  • Element:

    • Name: Git Repository (GitHub)
    • Type: Infrastructure
    • Description: The remote repository hosting the project's source code.
    • Responsibilities: Version control, collaboration, code review.
    • Security controls: Access controls, branch protection rules, code review policies.

  • Element:

    • Name: CI/CD Pipeline (e.g., GitHub Actions)
    • Type: Infrastructure
    • Description: An automated pipeline that builds, tests, and deploys the application.
    • Responsibilities: Building the application, running tests, creating release artifacts, deploying to app stores.
    • Security controls: Secure configuration of the pipeline, use of secrets management, code signing.

  • Element:

    • Name: App Store Connect (iOS)
    • Type: Platform
    • Description: Apple's platform for managing and distributing iOS applications.
    • Responsibilities: App review, distribution to users, managing app metadata.
    • Security controls: Apple's app review process, code signing requirements.

  • Element:

    • Name: Google Play Console (Android)
    • Type: Platform
    • Description: Google's platform for managing and distributing Android applications.
    • Responsibilities: App review, distribution to users, managing app metadata.
    • Security controls: Google's app review process, code signing requirements.

  • Element:

    • Name: User's iOS Device
    • Type: Device
    • Description: An iPhone or iPad running the Capybara app.
    • Responsibilities: Running the application, storing user data locally (encrypted).
    • Security controls: Device security features (e.g., passcode, biometric authentication), iOS security model.

  • Element:

    • Name: User's Android Device
    • Type: Device
    • Description: An Android phone or tablet running the Capybara app.
    • Responsibilities: Running the application, storing user data locally (encrypted).
    • Security controls: Device security features (e.g., passcode, biometric authentication), Android security model.

BUILD

graph LR
    A[Developer Workstation] -->|Commit & Push| B[GitHub Repository]
    B -->|Trigger| C[GitHub Actions (CI/CD)]
    C -->|Build Flutter App| D[Build Artifacts (APK, IPA)]
    C -->|Run Tests| E[Test Results]
    C -->|Code Analysis (SAST)| F[Security Scan Results]
    C -->|Dependency Check| G[Dependency Vulnerabilities]
    C -->|Sign Artifacts| H[Signed Artifacts]
    H -->|Publish| I[App Store Connect / Google Play Console]

    style A fill:#f9f,stroke:#333,stroke-width:2px
    style B fill:#ccf,stroke:#333,stroke-width:2px
    style C fill:#ccf,stroke:#333,stroke-width:2px
    style D fill:#ccf,stroke:#333,stroke-width:2px
    style E fill:#ccf,stroke:#333,stroke-width:2px
    style F fill:#ccf,stroke:#333,stroke-width:2px
    style G fill:#ccf,stroke:#333,stroke-width:2px
    style H fill:#ccf,stroke:#333,stroke-width:2px
    style I fill:#ccf,stroke:#333,stroke-width:2px
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Build Process Description:

  1. Development: Developers write code on their local workstations and commit changes to the GitHub repository.
  2. Trigger: A push to a specific branch (e.g., main or a release branch) triggers the GitHub Actions CI/CD pipeline.
  3. Build: The pipeline builds the Flutter application for the target platforms (iOS and Android), creating build artifacts (APK for Android, IPA for iOS).
  4. Testing: Automated tests (unit tests, integration tests) are executed to ensure code quality and functionality.
  5. Code Analysis (SAST): Static Application Security Testing (SAST) tools are used to scan the codebase for potential security vulnerabilities. Examples include linters and dedicated SAST scanners.
  6. Dependency Check: The project's dependencies are scanned for known vulnerabilities using tools like Dependabot or Snyk.
  7. Signing: The build artifacts are digitally signed using the appropriate developer certificates.
  8. Publish: The signed artifacts are uploaded to App Store Connect (for iOS) and Google Play Console (for Android) for distribution.

Security Controls in Build Process:

  • security control: GitHub Actions: Provides a secure and automated environment for building and testing the application.
  • security control: Secrets Management: Sensitive information (e.g., API keys, signing certificates) should be stored securely as secrets within GitHub Actions.
  • security control: SAST Tools: Help identify security vulnerabilities in the codebase early in the development lifecycle.
  • security control: Dependency Scanning: Helps prevent the use of vulnerable third-party libraries.
  • security control: Code Signing: Ensures the integrity and authenticity of the application, preventing tampering.
  • security control: Branch Protection Rules (GitHub): Enforce policies like requiring code reviews before merging changes to protected branches.

RISK ASSESSMENT

Critical Business Processes to Protect:

  • User Authentication and Authorization: Ensuring only legitimate users can access their password vaults.
  • Data Encryption and Decryption: Protecting the confidentiality and integrity of user data.
  • Data Storage and Retrieval: Ensuring data is stored securely and reliably.
  • Data Synchronization (if implemented): Securely synchronizing data across user devices.

Data to Protect and Sensitivity:

  • User Passwords (Highest Sensitivity): The most critical data to protect. Exposure would have severe consequences for users.
  • Usernames/Emails (High Sensitivity): Can be used for phishing attacks or to identify users on other services.
  • Website/Service URLs (Medium Sensitivity): Can reveal information about the user's online activity.
  • Other Password Vault Data (e.g., notes, secure notes) (Medium to High Sensitivity): Depending on the content, this data could be highly sensitive.
  • Encryption Keys (Highest Sensitivity): The compromise of these keys would render all encrypted data vulnerable.
  • Authentication Tokens (High Sensitivity): Could be used to impersonate users.

QUESTIONS & ASSUMPTIONS

Questions:

  • What is the specific key management strategy being used? How are encryption keys generated, stored, and rotated?
  • Are there any plans for formal security audits or penetration testing?
  • What are the specific Supabase Row Level Security (RLS) policies in place?
  • What are the plans for handling user data recovery in case of lost master passwords or device loss?
  • What level of logging and monitoring is implemented?
  • Is there a plan for handling potential denial-of-service (DoS) attacks?
  • Are there plans to support Multi-Factor Authentication (MFA)?
  • What specific Flutter secure storage mechanisms are being used?
  • What is the process for updating dependencies and addressing vulnerabilities?
  • Is there a disaster recovery plan in place for the Supabase backend?

Assumptions:

  • BUSINESS POSTURE: The project prioritizes security and user trust above rapid feature development.
  • BUSINESS POSTURE: The project aims for long-term sustainability and growth.
  • SECURITY POSTURE: Supabase is configured securely, including the use of Row Level Security (RLS).
  • SECURITY POSTURE: Developers follow secure coding practices.
  • SECURITY POSTURE: The Flutter client uses secure storage mechanisms for sensitive data.
  • DESIGN: The Supabase API is the primary communication channel between the client and the backend.
  • DESIGN: The CI/CD pipeline is securely configured and uses secrets management.
  • DESIGN: The application is designed to handle potential network interruptions gracefully.
  • DESIGN: The project will adhere to the security guidelines and requirements of the iOS and Android app stores.