Security review plan for Kaset

[Copilot]

Created a comprehensive security assessment plan for the macOS YouTube Music client covering authentication, network security, cryptography, data storage, and WebView attack surface.

Scope

10-phase security review covering:

• Authentication & Session - Cookie-based SAPISID token handling, WebKit data store persistence
• Network - HTTPS implementation, SAPISIDHASH computation (SHA1-based), API authentication flow
• Cryptography - Review SHA1 usage for auth tokens, SHA256 for cache keys
• Data Storage - WebKit persistent store, in-memory API cache, image cache
• WebView Security - JavaScript bridge (window.webkit.messageHandlers), script injection, CSP
• Input Validation - User input sanitization, URL construction, JSON parsing
• Entitlements - JIT compilation permission (com.apple.security.cs.jit), sandbox constraints
• Code Quality - Error handling, information disclosure in logs, Swift concurrency patterns
• Dependencies - No third-party frameworks identified (native Swift/SwiftUI)
• Documentation - Findings categorization (Critical/High/Medium/Low), remediation guidance

Key Areas of Interest

SAPISIDHASH Authentication

// YouTube Music requires SHA1-based auth token
let timestamp = Int(Date().timeIntervalSince1970)
let hashInput = "\(timestamp) \(sapisid) \(origin)"
let hash = Insecure.SHA1.hash(data: Data(hashInput.utf8))

JavaScript Bridge

// WebView communicates playback state via JS bridge
bridge.postMessage({
    type: 'STATE_UPDATE',
    isPlaying: true,
    progress: 45
});

Singleton WebView Pattern

• Single persistent WebView for DRM playback
• Survives window close for background audio
• JavaScript execution with JIT enabled

Original prompt

You are a world class security engineer. Provide a thorough security review for this app. Plan only

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