COLDCARD firmware

This update fixes a bug in the COLDCARD hardware wallet where a security mode called 'Delta Mode' could still access the Seed Vault through a feature called Seed XOR restore. Delta Mode is meant to restrict what an attacker or unauthorized user can do with the device. The fix blocks that access path. The bug was reported by someone named Rety.

This update fixes a bug in the COLDCARD hardware wallet's USB download command. Previously, a connected computer could ask the COLDCARD to read back almost anything it had temporarily stored in its extra memory chip (PSRAM), including uploaded transaction files or multisig setup files, even across different USB sessions and without encryption. Now the device only allows downloading the single most recent result it explicitly produced for the user (such as a signed transaction or backup), only over an encrypted session, and only until a new upload or session resets the permission.

This commit fixes a security bug where a malicious or compromised computer connected to a COLDCARD wallet could potentially swap the transaction data after the user reviewed it on the device screen but before the device signed it. The user might approve one transaction while the device signs a different one. The fix locks down the staged transaction data, re-checks it right before signing, and aborts with an error if anything changed.

This fix corrects a user-interface bug in COLDCARD's dice-roll seed-generation feature. Previously, if a user held down a digit key, the device treated the auto-repeating key events as multiple separate dice rolls, rapidly adding many unintended rolls. After the fix, a held key registers exactly one roll when released, matching how number entry already works elsewhere. This reduces the chance a user accidentally skews their random seed by holding a button too long.

This commit only removes an obsolete test from the test suite. The deleted test was for a duress PIN feature on the older Mk3 Coldcard and used a 'fetch' parameter that no longer exists. There is no change to firmware code that users run, so it cannot introduce a security vulnerability or fix one.

This commit only updates documentation. It clarifies that a BIP39 passphrase wallet backup stores an extended private key (XPRV) rather than the seed words or passphrase, and adds version numbers for older firmware behavior. There is no code change and no security fix or vulnerability introduced.

This commit only adds a single line to the changelog, describing a bugfix that was apparently already made elsewhere. The bug concerned how COLDCARD's 'View Seed Words' and backup features handled BIP-39 passphrase wallets when a passphrase was applied on top of a temporary seed. In that case, the device reportedly treated the master seed as the parent instead of the immediate temporary seed, potentially showing or backing up the wrong secret. Because the actual code change is not in this commit, we cannot directly verify the fix or assess its full security implications from this diff alone.

This commit changes how COLDCARD backup, clone, and Key Teleport features handle temporary seeds and BIP-39 passphrases. Previously, users could sometimes back up the main wallet even when a passphrase or temporary seed was active. Now the device always backs up the wallet currently in effect and warns the user first. This is a security-hardening change that reduces the risk of accidentally exposing or archiving the wrong secret, but it is not a fix for an active remote exploit.

This commit changes what the COLDCARD wallet displays on its 'View Seed Words' screen when a BIP-39 passphrase is active. Previously it showed the original 24 seed words plus a masked passphrase and the derived extended private key. Now it shows only the effective extended private key (and a note that a passphrase is in effect), hiding the underlying seed words. This is a deliberate UX/security hardening change, not a fix for an exploitable vulnerability.

This commit fixes a bug in the COLDCARD hardware wallet where, when the device is in 'Delta Mode' (a special temporary operating mode), opening the list of saved BIP-39 passphrases would reveal the passphrases and wallet fingerprints instead of securely wiping the seed first. The fix adds a call to wipe the seed if Delta Mode is active before displaying the saved passphrase menu. This prevents sensitive secret material from being exposed on screen in a mode meant to limit what an attacker can see.

This commit removes unused parameters from an internal function called fetch() in the COLDCARD firmware. There is no evidence this change fixes or introduces a security issue; it is purely a code cleanup that simplifies the function signature and removes dead code paths.

This commit only adds a thank-you credit to an upcoming release changelog. It does not change any code, so it cannot by itself fix or introduce a security issue. The actual BIP-322 validation bugfix must have been made in a different, earlier commit.

This update fixes how the COLDCARD hardware wallet's random-number generator (RNG) handles rare hardware faults. Previously, the device could silently continue using weak or repeated random numbers if the RNG reported a seed error. Now it detects those error flags, tries a safe recovery a few times, and if the problem persists it stops with an error instead of producing bad randomness. Two keyboard drivers were also updated so a temporary RNG failure does not lock the user out before login.

This commit fixes a buffer-validation bug in the COLDCARD Mk4 bootloader's secure callgate. The old code checked memory ranges using simple addition (address + length), which can overflow and trick the device into treating an attacker-controlled buffer as safe. The patch replaces those checks with subtraction-based math that cannot overflow, and also rejects negative input lengths. A security review by Karma-X is credited with the finding.

This update fixes a bug in the COLDCARD hardware wallet where signing a text message with the special 'Delta Mode' PIN would produce a signature that looked valid to anyone checking it. Delta Mode is a hidden feature that silently corrupts transaction signatures so attackers who force you to unlock your wallet cannot steal funds. The same protection was missing for message signatures, so an attacker could have tricked a victim into producing a seemingly valid signed message under duress. The fix makes message signatures produced in Delta Mode invalid, matching the existing behavior for transactions.