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Privacy considerations when Spending cycled UTXOs

Whirlpool has been designed with extensive privacy enhancing strategies that help make sure you do not undo the privacy gains of Whirlpool when you go to spend your UTXOs.

It is advised that you keep your funds within Whirlpool and directly spend using your Samourai Wallet on an as needed basis. This will allow you to take advantage of our superior coin selection and post mix spending tools, making it very hard to accidentally undo the privacy gains of Whirlpool.

Common Scenario:

I want to send my cycled UTXOs to another wallet / cold storage device

If you must transfer your UTXOs to another wallet / device then please follow the guidelines below:


  • Spend the entire balance in Whirlpool Postmix to a single address on your wallet / cold storage device. This is known as merging inputs and completely undoes the privacy gains provided by Whirlpool. 


  • Send less than half of your Whirlpool Postmix balance to your wallet / cold storage device. This is usually enough to trigger a STONEWALL which will provide a strong amount of entropy within the transaction.

  • If you need to transfer the entire balance then you should do so on a UTXO by UTXO basis. Using the Address Calculator in your Samourai Wallet generate the private keys for each of the PostMix UTXOs that you want to transfer and sweep them with your other wallet / device. You should ideally sweep each UTXO spaced apart by a random interval of time to avoid time correlation de-anonymization. 

Common Scenario:

I want to spend my coins at a third party service

Navigate to the PostMix Send Screen in your Samourai Wallet and create a transaction as you normally would. If it is possible your wallet will enable STONEWALL automatically - this will provide you with additional entropy and is considered the minimum requirement for sending from your PostMix balance with minimal privacy loss. 

If a STONEWALL cannot be created your wallet will warn you before sending. Please follow the guidelines below if you are unable to activate STONEWALL.


  • Ignore the warning. If STONEWALL cannot be activated, it means you are going to degrade your privacy and the privacy of your counterparts involved in the cycle. 


  • Spend a smaller amount. STONEWALL activates when spending less than half of your available balance.

  • Add more UTXOs to your Whirlpool wallet so that the amount you need to spend is less than half of your available balance.

  • Enlist the help of a friend to create a STONEWALLx2 transaction. This is very much like a normal STONEWALL but you are using a trusted friends UTXOs in addition to your own. This has the added benefit of additional mixing within the spend transaction and you can spend more than half of your available balance. 

Common Scenario:

I want to spend my coins to another Samourai Wallet user

Sending to another Samourai Wallet user is the same as sending to any bitcoin address and the same privacy rules apply. However, some additional Post Mix spending tools are available only between Samourai Wallet users. An example of this is Stowaway, which is a CoinJoin with a trusted friend that doesn't look like a CoinJoin and masks the true amount spent on the blockchain. 

Learn about Stowaway and how to create Stowaway transactions with Samourai Wallet

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