Wallet Update 0.97 - Coin Control, Dust TX alerts, Like-Type inputs and more.

It’s that time again, a new Samourai Wallet update has just dropped and is available for download on your Android device right now. As always the full list of changes is available on GitHub. We’re really excited about this release because it lays the foundation for a lot of exciting features coming down the line.

Coin Control

Coin Control is a powerful feature and nearly unheard of in most Bitcoin wallet software. To understand coin control, you first have to understand a little how your bitcoin wallet works under the hood. Samourai Wallet gives you access to a list of ‘Unspent Outputs’ in your wallet. Unspent outputs, are simply put, bitcoin in your wallet that can be spent as part of a new transaction. The combined amount of unspent outputs is equal to your total spendable balance. So if you have 2 Unspent Outputs of 0.5 BTC - your wallet would have a total spendable balance of 1 BTC. Coin control refers to the user having optional control over which unspent outputs get used when creating new transactions.

As of version 0.97, users will be able to mark any unspent output in their wallet as ‘Do Not Spend’. Any Do Not Spend output will not display as part of the total balance of the wallet and will not be used to create new transactions. The Do Not Spend tag is reversible at any time.

Blockchain Fungibility with like-type inputs and outputs

In the last update (v 0.96) we introduced the concept of matching like-type outputs when creating transactions on the blockchain. This meant, that if you were sent bitcoin to an address beginning with ‘3′ then the returning ‘change’ output will also be sent to an address in your wallet that begins with a ‘3′.

As of version 0.97 released today Samourai now will always attempt to create transactions with like-type inputs in addition to like-type outputs. This takes the anti fingerprinting measures a step further by making it incredibly difficult to link the sending addresses to the receiving addresses in a transaction on the blockchain, throwing a wrench in ways spies and snoops track the blockchain.

Dust Tracking Real Time Alerts

Speaking of blockchain snoops and spies… One of the methods in use to deanonymise bitcoin users is through a process called ‘Dusting’. When you’re Dusted you’ll receive a small bitcoin transaction into an address in your wallet. Eventually your wallet will combine this small amount of BTC into a larger transaction and reveal other addresses that can be linked to you with certainty, building a network graph of your wallet and transaction history.

In this version of Samourai Wallet, we have added real time Dust Alerting. If you wallet receives a low value transaction (anything less than 1000 satoshis) you will be alerted and given the choice to mark the dust output as ‘Unspendable’. If you see this alert and you weren’t expecting the incoming deposit we recommend blocking the transaction for your privacy. As always, the Unspendable tag is reversible if you decide to change your mind later.

Gifts for our power users

Some new tools our dedicated power users may find useful:

• Raw PushTX
  Push any signed transaction (hex format) to the bitcoin network - Available in Settings > Transactions > Broadcast Transaction Hex
• Sign message with Segwit address
  Sign any message with an active segwit (P2SH-P2WPKH) utxo privkey
• Show redeem script of Segwit utxo    

For our users who are keeping track, the SHA-256 APK hash for this release is:

2270e7c9b402447e5cc881f9d3eea4e5c72c08c55c47c70df0d3bf16cb5a6123

You can verify this matches the hash of your own wallet by navigating to the Settings > About > APK Hash screen.

Thank You

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