Crypto & Web3
Secure Seed Phrase and Private Key Input for Crypto Wallets
A seed phrase entered into a standard input is immediately visible to every script on the page. One browser extension, one XSS attack, and the wallet is drained. SmartField encrypts seed phrases at the keystroke level. The browser never sees the real words.
What Data This Protects
- Seed phrases
- Private keys
- Wallet addresses
- Recovery codes
Threats Blocked
- Clipboard hijacking
- Browser extension key theft
- XSS seed phrase extraction
- Keyloggers capturing recovery words
- Screen recording of wallet import
How It Works
Replace your standard HTML input with SmartField. 2 lines of code:
<script src="https://cdn.smartfield.dev/v1/smartfield.js"></script>
<smart-field type="password" placeholder="password"
encrypt-key="/api/sf-key"></smart-field>
Every keystroke is encrypted with AES-256-GCM. The AES key is wrapped with RSA-2048. Only your server can decrypt.
Why Standard Inputs Fail
A standard <input> stores plaintext in the DOM. Any JavaScript on the page can read it:
document.querySelector('input').value
// "MyBankPassword123" ← stolen
With SmartField, the same code returns:
document.querySelector('smart-field').value
// "eyJ2IjoxLCJpdiI6IkNx..." ← encrypted
Compliance
SmartField helps meet requirements for: MiCA (EU), Travel Rule
- AES-256-GCM (NIST SP 800-38D)
- RSA-2048 (NIST SP 800-56B)
- Zero-data architecture. SmartField never sees your data.
Frequently Asked Questions
Can a browser extension steal the seed phrase?+
Not with SmartField. Extensions read DOM content via JavaScript. SmartField stores data in a WeakMap inside a closed Shadow DOM. Extensions see cipher characters or encrypted payloads.
What about clipboard attacks?+
SmartField blocks copy, paste, select, drag, and context menu events. The clipboard never contains the seed phrase.
Does it work for wallet import flows?+
Yes. Use SmartField for the seed phrase input, then decrypt server-side to derive the wallet. The seed phrase never exists as plaintext in the browser.
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