[HIGH] Plaintext token fallback without user warning

[Tsukieomie]

Security Issue: Insecure Credential Storage Fallback

Severity: HIGH
Location: src/main/auth-store.ts:56-58

Description

When Electron's safeStorage is unavailable, credentials fall back to plaintext JSON with only a console warning.

Code

} else {
  console.warn("safeStorage not available - storing auth data without encryption")
  writeFileSync(this.filePath + ".json", jsonData, "utf-8")  // Plaintext!
}

Risk

• Credentials stored in plaintext JSON on systems where safeStorage is unavailable
• Only console warning, no user notification
• Migration from plaintext to encrypted doesn't inform user of previous security gap

Recommendation

Option 1: Fail Hard (Recommended)

} else {
  throw new Error("Cannot store credentials securely - safeStorage unavailable")
}

Option 2: Prominent UI Warning

• Show modal dialog warning user about insecure storage
• Require explicit user consent before storing plaintext
• Add persistent warning banner in UI

Option 3: Alternative Encryption

• Implement custom encryption for platforms without safeStorage
• Use user-provided passphrase
• Store encrypted locally

Impact

Medium-High - Affects security on systems without native credential storage support.

Labels: security, authentication