Toss Explores Compliant KRW Stablecoin Payments with Privacy Boost

Privacy Boost will safeguard merchant and consumer data in one of Korea's first institutional-grade, Won-backed digital currency initiatives

Sunnyside Labs, the team behind Privacy Boost, today announced a partnership with Toss to explore the development of a Korean Won-backed stablecoin. Over the next three months, the companies will conduct a PoC alongside Optimism to evaluate blockchain infrastructure for regulated digital financial services in Korea, with Sunnyside Labs providing the privacy layer that protects sensitive transaction data on a public network.

Toss is Korea's leading financial super-app, reshaping how millions engage with money. By unifying banking, payments, investing, credit, and taxes into one seamless platform, Toss has become the daily financial control center for over 30 million users. That is nearly two-thirds of South Korea's population.

Bringing a Won-backed stablecoin surfaces a challenge public blockchains have never fully solved: shielding transactions from public view without cutting off the oversight that regulated finance demands. Privacy Boost was built for exactly this. It combines zero-knowledge proofs (ZK) with trusted execution environments (TEE) to keep transaction details confidential while preserving full regulatory auditability through operator-held viewing keys. In the context of stablecoins, this means payments and remittances stay confidential to outside observers while remaining fully accessible to regulators and compliance teams.

Why does this matter? On a transparent public blockchain, every payment is visible to anyone. For a merchant, the exposure is total: scan the QR code at the counter, and every payment the store has ever received is there in real time, laid bare for a competitor next door to watch daily sales and peak-hour ticket sizes. For a consumer, the trail is just as revealing. Because merchant addresses are public, anyone who can match a specific payment to a purchase can trace it back to the sender's wallet, exposing health conditions, routines, and income.

The pilot program will test and verify two core capabilities:

• Privacy Boost from Sunnyside Labs, enabling confidential payments and remittances that protect merchant and consumer financial data while operating on a transparent, auditable network
• OP Enterprise from Optimism, giving financial institutions direct control over transaction ordering and processing to meet regulatory requirements around settlement and compliance

Over the coming months, we will share what we learn from the PoC as we work toward a production-ready framework for privacy-protected stablecoin payments in Korea.

If you are a financial institution, payment provider, or platform exploring stablecoin infrastructure, we would love to talk. Reach out at https://www.privacyboost.io/#contact