The debate around privacy in Web3 has always been polarized: how do you protect individual privacy while keeping bad actors out? The early “wild west” of legacy privacy solutions has drawn intense regulatory scrutiny, creating demand for a new generation of privacy protocols that combine cryptography with accountability.

Financial privacy is now about proving innocence without revealing identity, and RAILGUN's latest innovation, Private Proofs of Innocence, offers just that: a privacy solution that can withstand legal scrutiny.

We are proud to highlight this breakthrough from RAILGUN: a privacy-preserving, self-custodial compliance layer that has already stopped multiple high-profile abuse attempts.

What is Private Proofs of Innocence (PPOI)?

Private Proofs of Innocence is a decentralized bad-transaction prevention system built using zero-knowledge proofs. Its job is simple but powerful:

• Stop exploited, stolen, or sanctioned funds from entering the RAILGUN privacy system.

• Do it without revealing anything about the user’s identity, balances, or history.

This is not a centralized blacklist. Instead, it uses public blockchain data, combined with curated lists from industry-leading providers like Elliptic, ScamSniffer, PureFi, SlowMist, and Chainalysis Sanctions Oracle. Aggregated by the firm Private Proofs, Inc., these providers are the same forensic partners trusted by top exchanges and law enforcement worldwide.

You can explore the Private Proofs of Innocence activity live at ppoi.info.

How It Works

When tokens enter RAILGUN:

1. Shield: A user shields their tokens into the privacy system.

2. One-Hour Standby: A one-hour delay ensures List Providers can update their datasets.

3. Zero-Knowledge Proof: PPOI generates a blinded proof confirming that these tokens aren’t tied to any known malicious activity.

4. Ongoing Checks: Once verified, this proof follows those tokens through every subsequent private transaction.

If a token is flagged, it cannot enter privacy pools. The only action available is to return it to the original wallet, keeping the movement fully traceable. This design makes address-hopping useless for attackers. 

Private Proofs of Innocence is always effective against address hopping, up to any number of hops, as its list providers update the data live, as well as a one-hour pause before incoming tokens can be accepted.

Why This Matters

Unlike legacy compliance tools that require identity documents and centralized intermediaries, Private Proofs of Innocence offers:

• End-to-end privacy: No personal data is revealed.

• Decentralized assurance: List Providers contribute public data only.

• Transparent accountability: Anyone can verify flagged transactions at ppoi.info.

This is the most stringent compliance check in DeFi today, with no comparable system combining live forensic data and a mandatory waiting period.

Proof That It Works: Real-World Cases

Private Proofs of Innocence has already proven itself in multiple high-profile cases:

• Inferno Drainer – RAILGUN's implementation of Private Proofs of Innocence blocked $530,000 worth of tokens tied to the Inferno Drainer incident, preventing them from entering the privacy set.

• zkLend – The same mechanism later stopped $9.5M in tokens linked to the zkLend attack, a result that earned praise from Ethereum’s Vitalik Buterin as a “solid demonstration of compliant privacy in practice.”

Privacy For Honest Users, A Wall For Bad Actors

For users, Private Proofs of Innocence means:

• Assurance that you aren’t sharing a privacy set with flagged funds.

• Greater confidence for exchanges, protocols, and dApps that interact with RAILGUN.

• No additional risk or exposure; privacy is fully preserved.

For bad actors, it means RAILGUN privacy is off-limits.

Why Zokyo Cares

At Zokyo, our mission is to secure the next generation of decentralized protocols. Tools like RAILGUN’s PPOI are key examples of how cryptography can solve the compliance–privacy dichotomy without backdoors. We believe this is a model that other privacy protocols can learn from.

Explore PPOI for yourself.