COLDCARD CAN NOW SPLIT THE WALLET ALREADY ON THE DEVICE INTO CODEX32 SHAMIR SHARES — NO FUNDS MOVE AND THE WALLET DOES NOT CHANGE — SETS OF TWO TO NINE SHARES — THE DEVICE KEEPS NO COPY OF THE SET, SO RECORD EVERY SHARE BEFORE LEAVING THE SCREEN

Coinkite released COLDCARD firmware 5.6.3 for the Mk4 and Mk5 and 1.5.3Q for the Q on October 1, 2026. The main feature lets owners "split the wallet already on your device into Codex32 Shamir shares. No funds move, and the wallet does not change."

Codex32, defined by BIP-93, is "a checksummed format for wallet secrets." COLDCARD supports "sets of two through nine shares, with a threshold from two through the total." Pick two of three, and any two shares rebuild the seed while one alone does not.

The warning matters as much as the feature: "COLDCARD does not keep a share set after a split. Record and compare every share before leaving the split screen." The release also adds optional names for temporary seeds in the Seed Vault, block-height or time locks on individual inputs in PSBTv2, and stricter parsing that rejects malformed PSBTv2 files.

The checksum is the part you can check. A miscopied character shows up when the share is entered, not years later when the coins are needed. Whether the shares end up in different places, with different people, is the part no firmware can check for you. At the time of this writing, bitcoin was $84,132.