Key Teleport

Key Teleport is a feature designed for COLDCARD Q devices that lets you securely transfer:

• Seed phrases (words, xprv)
• Secure notes/passwords (singular or all in vault)
• Partially signed Bitcoin transactions (PSBTs) for multisig

It uses QR codes or NFC (with a helper website) for easy, reliable transmission, keeping your sensitive data protected every step of the way.

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How it works

1. Supported Transfers
   • Master Seeds (words, xprv)
   • Secure Notes/Passwords (single or all stored)
   • PSBTs during a multisig signing process
2. Encryption and Security
   • ECDH (Elliptic Curve Diffie-Hellman) for Session Key: Both devices generate a shared session key using ECDH.
   • AES-256-CTR Encryption: That session key encrypts the data with AES-256-CTR.
   • Additional Password Layer: A short password (stretched with PBKDF2-SHA512) adds a second AES-256-CTR layer.
3. Exchange Procedure
   • Receiver: Shows a QR code and a numeric code to the Sender.
   • Sender: Scans the Receiver's QR, then replies with its own QR code and an 8-character password.
4. Further Details
   • For deeper technical insights, see the protocol spec.