Learn how to upgrade here

Video: How to Upgrade Firmware

Mk4: Version 5.0.6 - July 29, 2022

• Security release: Virtual Disk feature updated with bugfix to address potential security concerns and new security hardening changes. Upgrade strongly recommended. More details in the Coinkite Blog.

Mk4: Version 5.0.5 - July 20, 2022

• Enhancement: BIP-85 derived passwords. Pick an index number, and COLDCARD will derive a deterministic, strong (136 bit) password for you. It will even type the password by emulating a USB keyboard. See new areas: Settings > Keyboard EMU and Settings > Derive Seed B85 > Passwords.
• Documentation: added docs/bip85-passwords.md documenting new BIP-85 passwords and keyboard emulation.
• Enhancement: BIP-85 derived values can now be exported via NFC, in addition to QR code.
• Enhancement: Allow signing transaction where foreign UTXO(s) are missing. Only applies to cases where partial signatures are being created. Thanks to @straylight-orbit
• Enhancement: QR Codes are now easier to scan in bright light. Thanks to @russeree for this useful fix!
• Bugfix: order of multisig wallet registration does NOT matter.
• Enhancement: Support import of multisig wallet from descriptor (only sortedmulti, BIP-67). Also support export of multsig wallet as descriptor.
• Enhancement: Address explorer can show "change" addresses for standard derivation paths for both single and multisig wallet.
• New tutorial: 2of2 multisig with 2x Coldcard signing device, and bitcoin-qt as coordinator, see docs/bitcoin-core2of2desc.md
• Enhancement: OP_RETURN is now a known script and is displayed in ascii when possible
• Bugfix: allow unknown scripts in HSM mode, with warning.

Mk4: Version 5.0.4 - May 27, 2022

• Enhancement: Optional USB protocol change which binds the ephemeral ECDH encryption keys more tightly. Best used in HSM mode where a single long-term USB connection is expected. Thanks to @DON-MAC-256 for this feature.
• Enhancement: In HSM mode, when more than 1k approvals, handle overflow in display, thanks to @straylight-orbit
• Enhancement: Adds support for "Regtest" which are testnet coins on an isolated blockchain. It's only useful for developers, and should not be used otherwise.
• Enhancement: Major rework of test setup to use BitcoinCore on regtest, and support Linux devs.
• Enhancement: Pause waiting for incoming NFC data increased to 3 seconds, from one. Better error reporting for debug purposes.
• Corrects obsolete domain name (coldcardwallet.com) in repro build script, thanks to @xavierfiechter
• Documentation: Secure element related fixes from @lucasmoten
• Bugfix: Error if clone (receiving end) started without first inserting SD card, fixed.
• Bugfix: Reproducible build issues corrected, thanks to @Ademan

Mk4: Version 5.0.3 - May 4, 2022

• Enhancement: Support P2TR outputs (pay to Taproot) in PSBT files. Allows on-screen verification of P2TR destination addresses (bc1p..) so you can send your BTC to them. Does not support signing, so you cannot operate a Taproot wallet with COLDCARD as the signing device... yet.
• Adds NFC support for exporting to all the various wallet-types.
• Multisig wallet specs can be exported via NFC, and new multisig wallet can be imported over NFC.
• Menu re-org:
  • "Export Wallet" now directly under Advanced Menu and duplicate link remains under File Management.
  • "Dump Summary" moved from Backup menu to Export
  • "Advanced" now "Advanced/Tools"
  • "New Wallet" renamed "New Seed Words"
  • Dice rolls (for new seed) moved from Import (a misnomer) to "New Seed Words"
• New users will see some prompts to help them get started, after seed is set.
• 12 word seeds are now an option from the start, either by TRNG or Dice Roll
• Duress wallet (from trick pin) will be 12-words if your true seed is 12-words
• Bugfix: allow sending to scripts that we cannot parse, with a warning, to support OP_RETURN and other outputs we don't understand well (yet).
• Bugfix: sending NFC things into the Coldcard was not working, fixed.
• Enhancement: Power-down during the login countdown now resets the time delay to force attacker (or yourself) to start over with full delay time.
• Enhancement: if an XFP of zero is seen in a PSBT file, assume that should be replaced by our current XFP value and try to sign the input (same for change outputs and change-fraud checks). This makes building a workable PSBT file easier and could be used to preserve privacy of XFP value itself. A warning is shown when this happens.
• Enhancement: "Advanced > Export > Export XPUB" provides direct way to show XPUB (or ZPUB/YPUB) for BIP-84 / BIP-44 / BIP-49 standard derivations, as a QR. Also can show XFP and master XPUB.

Mk3: Version 4.1.5 - May 4, 2022

• Enhancement: Support P2TR outputs (pay to Taproot) in PSBT files. Allows on-screen verification of P2TR destination addresses (bc1p..) so you can send your BTC to them. Does not support signing, so you cannot operate a Taproot wallet with Mk3 COLDCARD as the signing device.
• Bugfix: Yikes error shown during BIP-85 menu operation.
• Enhancement: Rename "Derive Entropy" to "Derive Seed B85" to match Mk4 menus

Mk3: Version 4.1.4 - Apr 26, 2022

• Enhancement: if an XFP of zero is seen in a PSBT file, assume that should be replaced by our current XFP value and try to sign the input (same for change outputs and change-fraud checks). This makes building a workable PSBT file easier and could be used to preserve privacy of XFP value itself. A warning is shown when this happens.
• Enhancement: "Advanced > Export XPUB" provides direct way to show XPUB (or ZPUB/YPUB) for BIP-84 / BIP-44 / BIP-49 standard derivations, as a QR. Also can show XFP and master XPUB.
• Bugfix: Updated domain name from coldcardwallet.com to coldcard.com in docs and few on-screen messages.
• Bugfix: allow sending to scripts that we cannot parse, with a warning, to support OP_RETURN and other outputs we don't understand well (yet).

Older releases and their changes are listed here, the full source code, hardware details, and much more can be found in our repository on github. Other downloads are listed here.

Upgrading Your COLDCARD's Firmware

Introduction

About Upgrades

Stay up to date on firmware releases - follow our Twitter account @COLDCARDwallet, or bookmark the Coinkite Blog.

Firmware upgrades provide new features, enhancements, bugfixes, and the latest security updates to your COLDCARD.

Firmware upgrade files have a .dfu file extension and should be approximately 690 KB in size. We use the abbreviation 20...-coldcard.dfu to represent the full firmware file name. Make sure to use the full file name in your commands.

COLDCARDs only load and run files signed by a Coinkite Inc. approved key.

Upgrade Menu

The Upgrade menu allows you to load an upgrade .dfu file from a microSD card.

Upgrade Menu Options

Show Version displays the version numbers of the firmware currently loaded on your COLDCARD.

From MicroSD lets you start the firmware upgrade process.

Bless Firmware marks the firmware upgrade as approved by the main PIN holder. This step is necessary if your COLDCARD loses power before the upgrade is confirmed.

Alternate Upgrade Methods

These instructions use a microSD card to upgrade the firmware. You can also upgrade by using the command-line tool or the Electrum plugin. On the Mk4, if USB drive emulation is enabled, you can simply copy the dfu file onto the COLDCARD.

Downgrading Firmware and Older Versions

Downgrading to an older firmware version is discouraged and may be blocked depending on your current firmware. Some firmware releases will prevent the bootloader from accepting older versions due to bugs or security issues found in older firmware. A limited selection of previously released firmware is available here.

Upgrade Procedure Using MicroSD

What You'll Need

• One COLDCARD
• microSD card (up to 32 GB capacity, FAT32 or FAT12 format)
• Micro USB cable, power-only preferred
• Power source for Micro USB cable, COLDPOWER or AC to USB adapter preferred
• Internet-capable device for downloading and saving files

What You'll Do

Check Your Current COLDCARD Firmware Version

1. Connect the COLDCARD to a power source with the Micro USB cable to turn it on.
2. Enter your PIN to unlock the COLDCARD.
3. Select Advanced > Upgrade > Show Version.
4. Compare the version shown on the screen with the latest version shown on coldcard.com/docs/upgrade. If your COLDCARD doesn't have the latest firmware version, it's time to upgrade.

Get the Latest Firmware

1. Go to coldcard.com/docs/upgrade if you're not already here. The latest firmware release will be at the top of the page.
2. Save the 20...-coldcard.dfu file to your microSD card or a folder on your computer.
3. Decide whether you will verify the firmware's hash and signature (strongly recommended) or load the firmware on your COLDCARD without verification.
4. Verifying? Go to the verification instructions.

Load the Latest Firmware on your COLDCARD

1. Save the 20...-coldcard.dfu file to your microSD card if you haven't done so already and eject the card once the file is saved.
2. Make sure your COLDCARD is turned on and unlocked.
3. Select Advanced > Upgrade > From MicroSD.
4. Press OK (✔) on your COLDCARD when you are prompted to pick the firmware image.
5. Select the firmware file.
6. The screen will say "Loading. . .". Be patient, this process takes time.

Note: When the screen changes to Verifying, the red LED will light up and stay lit until the firmware upgrade is complete. The red CAUTION LED lets you know changes are being made or have been made to your COLDCARD. If the COLDCARD is turned off after the new firmware is installed but before the first successful login, you will need to bless the firmware to turn the red LED off.

Do not turn off power to the Mk4 during it's 15-second upgrade process. Doing so will put it into a special recovery mode which requires a specially-prepared MicroSD card to be used.

Confirm and Finish Upgrade

1. Enter your PIN prefix when prompted after the COLDCARD reboots.
2. Verify whether or not you recognize the two words displayed on the screen. These words are hardware-specific to ensure you have the correct device. A different COLDCARD will display different words.
3. Enter the rest of your PIN when prompted.
4. The COLDCARD will perform another verification and the green GENUINE LED will light up.
5. Inspect your upgrade by selecting Advanced > Upgrade > Show Version. The firmware version you loaded will be displayed. You have successfully upgraded your COLDCARD's firmware!

Video Tutorial

Watch Max Hillebrand perform the firmware upgrade and verification process using Debian and a Mark 2 COLDCARD.

Optional Steps

Red LED Lit After Restart? Bless the Firmware

The red CAUTION LED is a safety feature warning you of unconfirmed changes to your COLDCARD. Only the main PIN holder can confirm changes. If you load new firmware and turn off the device before confirming the upgrade, the CAUTION LED will be lit the next time you turn on your COLDCARD. Blessing the firmware tells the COLDCARD that you are aware of and approve of the firmware upgrade.

1. Follow the prompts on the screen to log in to your COLDCARD.
2. Select Advanced > Upgrade > Bless Firmware.
3. The screen will say Verifying the green GENUINE LED will light up confirming your approval of the new firmware.

Once the firmware is blessed, your COLDCARD will light up the green LED on future startups.

Don't Trust. Verify the Firmware

Verifying the firmware's hash and signature requires intermediate to advanced computer skills. It uses extra tools and adds steps, but if you use a COLDCARD, you're probably security-conscious. In that case, you may find the extra effort to be worth the peace of mind you'll get from knowing your firmware is safe and correct.

Note: PGP signature verification requires GPG. Debian and other Linux distributions include GPG. Mac and Windows users who have not already installed GPG will need to do so. Operating system-specific instructions contain links to tool downloads.

Verifying on Mac

These instructions use GPG Keychain, a component of the GPG Suite from GPGTools.

You can also follow along with our video tutorial, How to Verify COLDCARD's Firmware.

Confirm the Hash

1. Open signatures.txt so you can view its contents.
2. Open Terminal, navigate to the directory where you saved the firmware and use the command shasum -a256 20...-coldcard.dfu.
3. Resize or reposition the windows so you can see both the Terminal and signatures.txt file at the same time.
4. Compare the output values in Terminal with the line of text in the signatures.txt file next to the firmware version you saved. The hash is confirmed if the values are the same.

Verify the PGP Signature

1. Save the signatures.txt file in the same location as the new firmware file.
2. Save the public key 4589779ADFC14F3327534EA8A3A31BAD5A2A5B10 as a new-pubkey.txt file in the same location as the firmware and signatures.txt files.
3. Open GPG Keychain.
4. Click the Import button and navigate to new-pubkey.txt. Select the file and click Open. A pop-up message should appear saying "Import successful".
5. Open Terminal and enter gpg --verify signatures.txt.
6. The output in Terminal should include Good signature from.... It is normal to see WARNING: This key is not certified with a trusted signature! gpg: There is no indication that the signature belongs to the owner. You may ignore the warning, the signature is verified.

Once the hash and signature are verified, load the latest firmware on your COLDCARD.

Verifying on Linux

Confirm the Hash

1. Open signatures.txt so you can view its contents.
2. Use the command line to navigate to the directory where you saved the firmware and enter the command sha256sum 20...-coldcard.dfu.
3. Resize or reposition the windows so you can see both the command output and signatures.txt file at the same time.
4. Compare the output value from the command with the line of text in the signatures.txt file next to the firmware version you saved. The hash is confirmed if the values are the same.

Verify the PGP Signature

1. Save the signatures.txt file in the same location as the new firmware file.
2. On the command line, enter curl "https://keyserver.ubuntu.com/pks/lookup?op=get&search=0xA3A31BAD5A2A5B10" | gpg --import to import the public key.
3. Next, enter gpg --verify signatures.txt to verify the file's signature versus its content.
4. The command output should include Good signature from.... It is normal to see WARNING: This key is not certified with a trusted signature! gpg: There is no indication that the signature belongs to the owner. You may ignore the warning, the signature is verified.

Once the hash and signature are verified, load the latest firmware on your COLDCARD.

Verifying on Windows

These instructions use Kleopatra, which is a part of Gpg4win (GNU Privacy Guard for Windows). You only need the GnuPG Privacy Guard and Kleopatra components to verify the PGP signature.

Kleopatra requires you to have an OpenPGP signature to complete verification. If you don't have a signature to import, you can make one in Kleopatra.

Confirm the Hash

1. Open signatures.txt so you can view its contents.
2. Open Command Prompt and enter certutil -hashfile C:\..\20...-coldcard.dfu SHA256, where C:\..\20...-coldcard.dfu is the full path to the saved firmware file.
3. Resize or reposition the windows so you can see both the Command Prompt output and signatures.txt file at the same time.
4. Compare the output values in Command Prompt with the line of text in the signatures.txt file next to the firmware version you saved. The hash is confirmed if the values are the same.

Verify the PGP Signature

1. Save the text from signatures.txt with an .asc file extension in the same location as the saved firmware file. Do not save the file as .txt, Kleopatra will not recognize it.
2. Save the public key 4589779ADFC14F3327534EA8A3A31BAD5A2A5B10 as an .asc file in the same location as the firmware and signatures.asc files.
3. Open a browser and go to keybase.io/DocHex. Click on the text next to the key icon to open the public key window. You will need this window for a later step.
4. Open Kleopatra and click Import....
5. Navigate to the public key .asc file and open it.
6. You will be asked to check the fingerprint of the file and given suggested options. The Keybase public key window is the trusted website. Click Yes.
7. A Certify Certificate window will show the file's fingerprint, your certification, and the fingerprint's owner - in this case, Peter D. Gray. Resize or reposition the Certify Certificate window and the browser window opened in step 3 so you can see them both at the same time.
8. Make sure the fingerprints in each window match and click Certify. If you have a passphrase on your certificate, you'll be asked to enter it. A pop-up box should appear saying, "Certification successful." Click Ok.
9. Click Decrypt/Verify... and open signatures.asc.
10. Kleopatra will verify the signature. You may save or discard the file Kleopatra generates, it is not needed. The signature is verified.

Once the hash and signature are verified, load the latest firmware on your COLDCARD.