Coinkite Inc., a leader in bitcoin security solutions,recently announced major firmware updates for its flagship COLDCARD Mk4 (v5.4.2) and premium COLDCARD Q (v1.3.2) hardware wallets. The updates introduce COLDCARD Co-Sign (CCC) and Key Teleport, two transformative features designed to redefine secure bitcoin storage and multisig transaction workflows.
Revolutionizing Multisig Security with COLDCARD Co-Sign (CCC)
The COLDCARD Co-Sign feature introduces enterprise-grade spending controls by integrating a Spending Policy Key (Key C) into the wallet’s security framework. This innovation transforms the COLDCARD into a programmable hardware security module (HSM), enforcing customizable rules such as:
- Spending Limits: Set monetary thresholds or velocity restrictions.
- Whitelisting: Approve transactions only to predefined addresses.
- 2FA Authentication: Add an extra layer of approval for fund access.
CCC operates within a 2-of-N multisig structure, requiring collaboration between the device’s Main Seed, Key C, and Backup Keys. Policy violations trigger automatic transaction denials, while authorized users retain override capabilities via Backup Keys. 
A step-by-step setup guide is available here.
Key Teleport: Secure, Instant Data Transfer for COLDCARD Q
Exclusive to the premium COLDCARD Q model, Key Teleport enables encrypted transfers of sensitive data—including seed phrases, PSBTs, and secure notes—between devices via QR codes or NFC. Integrated with a dedicated helper website, the feature ensures end-to-end security without exposing data to third parties.
Key Teleport streamlines multisig workflows by allowing users to:
- Finalize Transactions On-Device: Complete and broadcast multisig PSBTs directly via NFC’s PushTX.
- Export to Alternate Media: Flexibly save signed PSBTs to SD cards, even if received via QR.
- Share Seamlessly: Automatically route transactions to predefined cosigners using shared pubkeys.
Enhanced Performance & Usability Upgrades
Both firmware versions include critical optimizations:
- 10% Faster USB Uploads: Improved handling of large files.
- NFC Export Persistence: Continuous NFC transmission until manually canceled.
- QR Code Optimization: COLDCARD Q prioritizes larger, scannable QR displays.
- Bitcoin Safe Compatibility: Direct wallet exports to the Bitcoin Safe standard.
Notable bug fixes address progress bar errors, derivation path displays, and Trick PIN conflicts.
Availability & Resources
The firmware updates are live for all COLDCARD Mk4 and Q users. Download instructions and full release notes are available on GitHub.
About Coinkite Inc.
Coinkite builds uncompromising bitcoin security tools, including COLDCARD, Opendime, and SatCard. Founded in 2013, the company champions open-source development, verifiable hardware, and user sovereignty.
