A single transaction combining no-KYC and KYC Bitcoin can expose years of supposedly private activity, according to Seth for Privacy, chief operating officer of Cake Wallet, who discussed privacy best practices on the Bitcoin Rails podcast.
The risk stems from how Bitcoin wallets function. Rather than holding a single balance, wallets manage a collection of separate unspent transaction outputs (UTXOs)—discrete "coins" from specific past transactions. When sending a payment larger than any individual UTXO, wallets automatically combine multiple outputs as inputs to the same transaction.
"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, highlighting a common mistake users make through passive wallet behavior.
Bitcoin privacy has become a focal point following legal action against Samourai Wallet developers last year. However, recent developments have shifted momentum toward privacy advocates: the U.S. Department of Treasury scrapped two long-stalled crypto surveillance proposals this week.
Seth noted that Western citizens have historically shown less urgency around privacy protections compared to people in more restrictive jurisdictions. However, attitudes are shifting. "In the last five or six years a lot of people—even in the West—are starting to think privacy really matters," he said.
Cake Wallet, a privacy-focused, self-custody, open-source wallet, recently integrated Bitcoin's Lightning Network, which offers faster transactions and enhanced privacy compared to the main blockchain. Seth emphasized that broader adoption of privacy-enhanced tools matters more than perfect privacy in niche solutions, suggesting that improving Bitcoin's native privacy capabilities could reduce reliance on alternative privacy coins.
