Privacy infrastructure for web3

Shield. Send. Prove.

Private payments · ZK-SNARKs · Stealth addresses · Multi-chain

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261
Passing tests
5
Chains supported
3
Contracts deployed
17
Packages
10
MCP tools
Shielded Payments Stealth Addresses (ERC-5564) Groth16 ZK Proofs Poseidon Merkle Trees Multi-Chain Privacy MCP Server Integration AI Agent Payments Railgun Adapter Bittensor EVM Policy Engine Open Source 261 Passing Tests Shielded Payments Stealth Addresses (ERC-5564) Groth16 ZK Proofs Poseidon Merkle Trees Multi-Chain Privacy MCP Server Integration AI Agent Payments Railgun Adapter Bittensor EVM Policy Engine Open Source 261 Passing Tests

01 / How It Works

Private by default.
Proven on-chain.

Peek-a-boo is privacy infrastructure for web3. Shield tokens, route through stealth addresses, and prove membership with zero-knowledge proofs — across multiple chains.

— 01
Shield
Deposit tokens into a shielded pool. A Poseidon commitment enters the Merkle tree. Your identity stays off-chain. Supports ETH, ERC-20, and TAO.
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— 02
Route
A fresh ERC-5564 stealth address is generated per payment. Recipients scan with a viewTag filter. No public linkability between sender and receiver.
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— 03
Prove
Generate a Groth16 ZK proof of pool membership. The on-chain verifier checks the proof and releases funds. No link between your deposit and withdrawal.
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02 / Features

Everything you need.
Nothing you don't.

Shielded Pool
ZK-SNARK deposits and withdrawals. Poseidon Merkle tree with 30-root history buffer. Double-spend prevention via nullifier registry.
Stealth Addresses
ERC-5564 ECDH key exchange. One-time addresses per payment. viewTag fast-scan filter for efficient recipient scanning.
Policy Engine
Per-transaction and cumulative spend limits. Time-bound rules with timezone support. Whitelist, denylist, and chain restrictions.
Multi-Chain
Bittensor EVM mainnet. Ethereum, BSC, Polygon, Arbitrum via Railgun. Aztec adapter planned. Same interface across all chains.
MCP-Native
10 MCP tools for AI agents. Works with Claude, LangChain, CrewAI. Shield, unshield, transfer, prove — all as tool calls.
Open Source
17 packages. 261 passing tests. Pure JS cryptography via @noble/curves. No native bindings. Fully auditable.

03 / Bittensor

Built for Bittensor

Peek-a-boo was born on Bittensor. Shielded TAO payments, anonymous miner participation, and private inference routing — all powered by ZK-SNARKs on Subtensor EVM. Contracts are live on mainnet (Chain 964).

Explore Bittensor →
Mainnet

Chain ID 964 · ShieldedPool, StealthAnnouncer, Groth16Verifier deployed · TAO native currency · 20-level Poseidon Merkle tree

04 / Stack

Built in the open.
Production-grade.

17 packages. Turborepo monorepo. Multi-chain privacy with Bittensor, Railgun, Ethereum L2, and Aztec adapters.

@pas/core
Policy engine, sessions, shielded treasury, stealth addresses
@pas/contracts
ShieldedPool · StealthAnnouncer · Groth16Verifier · Poseidon
@pas/storage-sqlite
WAL-mode SQLite persistence · 8 tables · 41 tests
@pas/adapter-railgun
Shielded ERC-20 via ZK-SNARKs — 74 passing tests
@pas/adapter-bittensor
Subtensor EVM · Chain 964/945 · TAO native currency
@pas/crypto
Poseidon hashing, Merkle trees, Groth16 proof generation
@pas/types
Shared type definitions across 9 modules
@pas/sdk
Universal privacy interface — high-level agent API
@pas/mcp-server
MCP tools for any MCP-compatible agent
@pas/settlement
L1/L2 providers · gasless relay
@pas/agent-langchain
LangChain tool wrappers around SDK
@pas/agent-crewai
CrewAI tool wrappers around SDK
@pas/adapter-aztec
Native private execution — deepest guarantees
Complete In progress Planned
261
Passing tests
17
Packages
7
Phases done
~1M
Max deposits

05 / FAQ

Frequently asked
questions

What is Peek-a-boo?+
Peek-a-boo is privacy infrastructure for web3. It provides shielded payments, stealth addresses, and ZK-proof withdrawals across multiple chains — Bittensor EVM, Ethereum via Railgun, and more. It works for both human users and AI agents via MCP tools.
Which chains are supported?+
Bittensor EVM (mainnet, chain 964) is the primary deployment with live contracts. Railgun adapter supports Ethereum, BSC, Polygon, and Arbitrum. Ethereum L2 and Aztec adapters are planned.
How does the ZK proof work?+
A Circom Withdraw circuit generates a Groth16 proof proving the agent knows a (nullifier, secret) pair whose Poseidon hash is a leaf in the on-chain Merkle tree. The contract verifies the proof, checks the nullifier registry to prevent double-spend, then releases funds to the recipient. Public inputs — root, nullifierHash, recipient, amount — are bound via a square constraint trick to prevent front-running.
Is it open source?+
Yes. 17 packages, 261 tests, all MIT licensed. Pure JS cryptography via @noble/curves — no native bindings, fully auditable. Built with npm workspaces and Turborepo.
How do I integrate with my agent?+
The @pas/mcp-server package exposes all privacy operations as MCP-compatible tools. Any agent that supports MCP (Claude, OpenClaw, custom daemons) can call shield, unshield, and stealth routing natively. LangChain and CrewAI wrapper packages are actively being developed for direct framework integration.

Open source privacy infrastructure

Hide in
plain sight.

Multi-chain · ZK proofs · 261 tests · MCP-native

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