@metamask/toprf-secure-backup

@metamask/toprf-secure-backup

Installation

yarn add @metamask/toprf-secure-backup

or

npm install @metamask/toprf-secure-backup

Contributing

This package is part of a monorepo. Instructions for contributing can be found in the monorepo README.

Security Considerations

This SDK handles sensitive cryptographic material including passwords, seeds, authentication tokens, and private keys.

JavaScript Memory Limitations

Important: JavaScript's garbage collector provides no guarantees about when sensitive data is removed from memory. While the SDK performs best-effort cleanup internally, complete memory clearing cannot be guaranteed.

Best Practices

1. Minimize sensitive data lifetime - Use keys immediately, don't store in variables
2. Avoid framework state - Don't store keys in React state, Redux, or similar
3. Clear references - Set variables to null and call array.fill(0) when done

// ✅ Good: Use immediately and clear
async function decrypt(data) {
  const { encKey } = await toprfBackup.recoverEncKey(params);
  try {
    return await processData(data, encKey);
  } finally {
    encKey.fill(0);
  }
}

// ❌ Bad: Long-lived storage
this.encKey = result.encKey; // Persists in memory

Potential Risks

• XSS attacks accessing memory
• Malicious browser extensions
• Memory inspection via developer tools
• System-level memory dumps

The SDK internally clears sensitive Uint8Array data (session keys, password bytes, seeds) where possible, but JavaScript strings and BigInts cannot be reliably cleared from memory.