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My vault uses Coldcards. Should I use Slipstream to submit my transaction?

Perform a Slipstream transaction to protect your bitcoin transaction against certain attacks.

Coinkite, the makers of Coldcard, disclosed a vulnerability affecting private key generation on some of its devices. Unchained clients with vaults where 2 of 3 private keys were generated on a Coldcard are vulnerable.

Any bitcoin in reused addresses (addresses that were previously spent from) is at immediate risk of loss. If you are in this situation, consult the emails you received from Unchained for immediate next steps.

If you do not have bitcoin in addresses that were reused, then your bitcoin is less likely to be at immediate risk of loss. We still recommend moving this bitcoin to a new vault by performing a sweep transaction using new keys generated on secure hardware wallets.

The risk of “RBF sniping”

Unfortunately, because the underlying private keys are vulnerable, broadcasting the sweep transaction to the public bitcoin mempool could temporarily expose that bitcoin to an "RBF sniping" attack.

To mitigate this risk, you can instead submit the sweep transaction directly to a bitcoin mining pool, bypassing the public mempool entirely. This approach requires you to trust the chosen mining pool.

When initiating a transaction from your Unchained vault, Coldcard users will now see the option to perform either a Slipstream transaction or a normal transaction.

What is Slipstream?

Slipstream is a specialized direct-to-miner solution operated by MARA Holdings, a mining company publicly traded on Nasdaq. Instead of sending your transaction to the public bitcoin mempool, Slipstream transmits it to a mining partner, allowing it to be included in a block without entering the public mempool.

 Note: We have enabled this feature for users we believe to be impacted.

A Slipstream transaction will:

  1. Generate a bitcoin transaction that moves all bitcoin from the source vault to an address of your choosing (for example, an address in a new Unchained vault with newly generated keys).
  2. Require you to sign the transaction with your existing keys.
  3. Be sent directly to a bitcoin miner through Slipstream instead of being broadcast to the public bitcoin network.
  4. Be monitored on the Slipstream website rather than in the Unchained app or a public block explorer. Unchained will provide a link to the Slipstream transaction.
  5. Be mined in an upcoming block without entering the public mempool. Unchained will detect the confirmation and update your wallet balances automatically.

 

How to use Slipstream at Unchained:

  1. Initiate a withdrawal from a vault. The minimum fee rate is higher to help ensure the transaction is included in a block through Slipstream.
  2. After the transaction is fully signed, you will be prompted to choose either Slipstream or the standard broadcast option.
  3. Select your preferred broadcast method.

 

Caution: This feature involves you placing some trust in the operators of Slipstream. Unchained does not operate Slipstream. It is operated by Mara Holdings, Inc., a mining company which is publicly traded on the NASDAQ. Unchained does not control or have liability for the actions of Mara.