Introduction
MARC Protocol is the privacy layer for all AI agent payment protocols.
What is MARC Protocol?
MARC (Modular Agent-Ready Confidential) Protocol is the universal privacy layer for AI agent payments, built on Zama's fhEVM. It uses Fully Homomorphic Encryption (FHE) to hide payment amounts on-chain while keeping sender and recipient addresses public. MARC is not tied to any single payment standard. It sits underneath all major agent payment protocols as a shared confidential settlement layer.
What is FHE?
Fully Homomorphic Encryption (FHE) is a cryptographic technique that allows computations to be performed directly on encrypted data without ever decrypting it. The result of the computation, when decrypted, is identical to performing the same operation on the plaintext. In the context of MARC Protocol, this means smart contracts can add, subtract, and compare token balances while they remain encrypted on-chain — no validator, sequencer, or block explorer ever sees the actual amounts.
Supported Agent Payment Protocols
x402 (HTTP 402 payments), MCP (Model Context Protocol), MPP (Machine-Payable Protocol), A2A (Agent-to-Agent by Google), AgentKit (Coinbase), Virtuals GAME, OpenClaw, and any future agent payment framework. Any agent, any framework, any chain. Private payments by default.
“Crypto privacy is needed if you want to make API calls without compromising the information of your access patterns. Even with a local AI agent, you can learn a lot about what someone is doing if you see all of their search engine calls. [...] providers will demand an anti-DoS mechanism, and realistically payment per call.”
Vitalik Buterin, March 2026
The Problem
AI agents are transacting at scale across x402, MCP, A2A, and other protocols. But every payment amount, every balance, every transaction outcome is publicly visible on-chain. This enables:
- * Strategy leakage. Competitors monitor each other's API spend
- * MEV extraction. Visible amounts enable front-running
- * Price discrimination. Servers adjust pricing based on spending patterns
- * Competitive intelligence. Payment history reveals operational strategy
The Solution
MARC Protocol encrypts what matters: amounts and balances are FHE-encrypted, while participants remain public for protocol compliance. Regardless of which agent payment protocol is used, agents wrap USDC into encrypted cUSDC (ERC-7984), transfer it peer-to-peer with zero fees and hidden amounts, and unwrap back to USDC when done.
| What | Visible? |
|---|---|
| Transfer amount (cUSDC) | Encrypted (FHE) |
| cUSDC balance | Encrypted (FHE) |
| Wrap/unwrap amount | Visible (USDC enters/exits) |
| Sender address | Visible (protocol requirement) |
| Recipient address | Visible (protocol requirement) |
| Transaction occurred | Visible (events emitted) |
How FHE Works
Fully Homomorphic Encryption allows computation on encrypted data without decryption. In MARC Protocol:
- Agents encrypt their payment amount client-side using
fhevmjs - The encrypted value is sent to the contract as an
euint64 - The contract performs arithmetic (balance subtraction, addition) on encrypted values
- Only the KMS (Key Management Service) can decrypt, triggered only by
unwrap
The smart contract never sees plaintext amounts during transfers. Balance checks use FHE comparison. If insufficient, the contract silently transfers 0 instead of reverting (the silent failure pattern).
Three ERC Standards
MARC Protocol integrates three complementary ERC standards:
ERC-7984: Confidential Token
Wrap USDC to encrypted cUSDC. Fee-free peer-to-peer transfers with hidden amounts.
ERC-8004: Agent Identity
On-chain agent registration, wallet linking, and proof-of-payment reputation.
ERC-8183: Agentic Commerce
Job escrow for multi-step agent workflows with 1% completion fee.
Key Features
- * Token-centric. Agents hold encrypted cUSDC in their own wallets (no pool contract)
- * Fee-free transfers.
confidentialTransfer()costs zero protocol fee - * Wrap/unwrap fees. 0.1% (min 0.01 USDC) only when entering/exiting
- * Silent failure. No balance info leaked through reverts
- * Protocol-agnostic. Works with x402, MCP, MPP, A2A, AgentKit, Virtuals GAME, OpenClaw, and more
- * 800+ tests. Contract, on-chain, SDK, and plugin tests
Quick Example
import { fheFetch } from "marc-protocol-sdk";
// Automatically handles 402 responses with encrypted payments
const response = await fheFetch("https://api.example.com/data", {
tokenAddress: "0xE944754aa70d4924dc5d8E57774CDf21Df5e592D",
verifierAddress: "0x4503A7aee235aBD10e6064BBa8E14235fdF041f4",
rpcUrl: "https://sepolia.infura.io/v3/YOUR_KEY",
signer: wallet,
fhevmInstance: fhevm,
});
const data = await response.json();