Here’s How Not To Screw Up Your Bitcoin Privacy

Just one transaction can compromise years of discreet Bitcoin activity, Cake Wallet’s chief operating officer has warned. 

Speaking on the Bitcoin Rails podcast this week, activist Seth for Privacy talked about different ways of protecting one’s privacy when using Bitcoin and said that focusing on privacy was a must for the West. 

Bitcoin privacy is a hot topic again ever since the developers of private coin mixer Samourai Wallet went on trial last year and were subsequently imprisoned. 

But just this week, the U.S. Department of Treasury scrapped two long-stalled crypto surveillance proposals, handing a major win to privacy advocates and the digital asset industry.

“If you ever spend your no-KYC coins with one of your KYC coins — which if you just let the wallet do its thing, it could do because it doesn’t know the difference — you immediately connect all of the non-KYC Bitcoin that you spend in that with your identity,” Seth said, referring to UTXO management, also called “coin control” by some wallets. 

Bitcoin wallets don’t hold a single balance but a collection of separate unspent transaction outputs — UTXOs — each one a discrete “coin” from a specific past transaction. 

When you send a payment larger than any one UTXO, the wallet picks several and combines them as inputs to the same transaction — an easy mistake to make, Seth highlighted.