Edge Firmware for Coldcard Mk4 - Developer Preview

Edge is an experimental firmware for Coldcard Mk4, dedicated to developers who might want to play around with the latest up and coming Bitcoin tech that is not fail-proof yet.

Edge Firmware for Coldcard Mk4 - Developer Preview
  • “Edge Firmware for Mk4 will be updated more frequently and contain the very latest in BIP’s and other upcoming tech for Bitcoin, but it's not for everyday hodlers: it’s for the wallet developers and power users who are itching to experiment with new types of signatures, and complex new on-chain wallet types."
  • Disclaimer: "Do not use this firmware on your main stash. Do not run it to impress potential sexual partners."
  • "Winning features from “edge” will be moved to the normal firmware only when they are ready, and we are still developing new and practical features on both branches. Isolating the riskier stuff allows us to concentrate on everyday features, that everyone can use right away, while the Bitcoin community develops supporting code for new types of signatures and consensus related changes."

v6.0.0x - First Edge release


  • Taproot keyspend & Tapscript multisig sortedmulti_a (tree depth = 0)
  • Paper wallets can be P2TR address format.
  • Limitations:
  • only TREE of depth 0 is allowed
  • max 32 signers in TR multisig, only allowed script is: sortedmulti_a
  • if we can sign by both key path and script path: key path has precedence.
  • Full technical details available here.

BIP-0129 Bitcoin Secure Multisig Setup (BSMS)

BSMS menu example

Fixes & Common Enhancements

  • Enhancement: change Key Origin Information export format in multisig addresses.csv according to BIP-0380 (m=0F056943)/m/48'/1'/0'/2'/0/0 –> [0F056943/48'/1'/0'/2'/0/0]
  • Bugfix: correct scriptPubkey parsing for segwit v1-v16
  • Bugfix: do not infer segwit just by availability of PSBT_IN_WITNESS_UTXO in PSBT

These have been fixed on master as well, but are not yet part of a release.

What’s Next

Obviously… Miniscript!

GitHub Repo
Blog Post / Archive