A core design constraint of the Interphase Protocol is zero custom custody escrow contracts on source and destination chains. We do not deploy or maintain custom asset bridges, omnibus pool contracts, or custom custody vaults on Ethereum, Base, Solana, Bitcoin, or Sui.

The Mental Model ("The Blind Courier"):
Imagine Alice places $5,000 in a standardized bank vault on Ethereum and receives a cryptographic ticket. She writes her secret delivery instructions inside a sealed envelope and hands it to a group of blindfolded examiners inside a secure room (COTI Garbled Circuits). The examiners check that the money is clean, permanently shred Alice's name and signature off the ticket, and push an anonymous work order out the door: "Deliver 5,000 USDC to single-use address P_stealth on Solana, get reimbursed on Ethereum." An independent courier (The Solver on NEAR Intents) fulfills the delivery without ever knowing Alice exists.

1. Phase 1: Source Vault Deposit with Blind Commitment Hash

   When Alice initiates a transfer (e.g. from Ethereum to Solana), her client does not write plaintext routing details to the blockchain. Instead, she deposits into the standard NEAR multichain deposit vault with a cryptographic commitment:

   H_intent = Keccak256(nonce ‖ nullifier ‖ encryptedPayloadHash)

   On-Chain Trace: On Etherscan or block explorers, observers only see that 0xAlice transferred 5,000 USDC into the NEAR Multichain Vault matching H_intent. It is mathematically impossible to infer the target chain (Solana), the destination asset, or the recipient.

2. Phase 2: Soda Labs Metadata Privatization on COTI L2

   Alice’s client encrypts the intent parameters using the COTI Network MPC Public Key (@coti-io/coti-ethers). To solve the EVM metadata leak confirmed by Soda Labs (where standard EVM headers expose tx.origin):

   • Oblivious HTTP (OHTTP) Relay: The client dispatches the encrypted JSON-RPC request through an OHTTP gateway, completely stripping Alice’s IP address and ISP fingerprint.
   • Gasless Paymaster Envelope: The transaction on COTI L2 is broadcast by our Paymaster relayer account. The EVM header permanently records: from: 0xInterphasePaymaster. Alice’s personal wallet address never appears in the COTI block header.
   • Calldata Homomorphic Padding: Payloads are uniformly padded to 512 bytes to defeat packet-length timing analysis.
3. Phase 3: The Garbled Circuit "Blind Sanitizer" (InterphaseCotiRouter.sol)

   Inside our deployed contract on COTI L2 (InterphaseCotiRouter.sol), the MPC validator cluster evaluates the encrypted payload inside Yao's Garbled Circuits:

   // Pseudocode of Garbled Circuit MPC Logic inside InterphaseCotiRouter.sol
   function evaluatePrivateIntent(
       bytes calldata encryptedPayload, 
       bytes32 depositCommitment
   ) external returns (SanitizedOrder memory order) {
       // 1. Decrypt inputs into private wire labels inside MPC
       (address sourceSender, uint32 destChain, bytes32 pStealth, uint256 amount) = mpcDecrypt(encryptedPayload);
   
       // 2. Blind Sanctions Screening (ComplianceSMT.sol)
       bool isClean = complianceSMT.verifyNonInclusion(sourceSender);
       require(isClean, "Sanctions Violation");
   
       // 3. Stateful 24-Hour Rolling Identity Velocity Limiter
       enforceRollingVelocityLimit(sourceSender, amount);
   
       // 4. Identity Stripping: Only output wires are revealed!
       // sourceSender is permanently erased from memory.
       order = SanitizedOrder({
           destChainId: destChain,
           stealthRecipient: pStealth,
           payoutAmount: amount,
           depositCommitment: depositCommitment
       });
       
       emit PrivateIntentEvaluated(order);
   }

4. Phase 4: Solver Bidding & Destination Stealth Settlement

   The sanitized order is emitted into the NEAR Intents solver market (intents.near / Defuse).

   What the Solver Sees:
   The market maker only sees: "Deliver 5,000 USDC to Solana stealth address P_stealth. Claim reimbursement for H_intent from NEAR Ethereum Vault." The solver has zero visibility into who deposited on Ethereum.

   Destination Address Derivation (ECDH Math):
   The recipient’s address P_stealth is generated client-side using non-interactive Elliptic Curve Diffie-Hellman:

   Ephemeral Public Key: R = r · G
   Shared Secret Point: S_shared = r · V_recipient = v_recipient · R
   One-Time Stealth Address: P_stealth = S_recipient + Keccak256(S_shared) · G

   The solver transfers 5,000 USDC + an atomic native gas subsidy (e.g. 0.005 SOL) to P_stealth. The recipient sweeps the funds locally using their private spending key p_stealth = s + Keccak256(S_shared).

5. Phase 5: Solver Reimbursement via NEAR Chain Signatures

   Once the settlement transaction finalizes on Solana (32-slot commitment gate):

   1. The solver presents the Solana block inclusion receipt to the NEAR Intents engine.
   2. NEAR’s decentralized validator network (Chain Signatures TSS MPC) validates the destination receipt against H_intent.
   3. NEAR MPC issues a cryptographic signature instructing the NEAR Multichain Deposit Vault on Ethereum to release Asset X directly to the solver’s authenticated reimbursement wallet.

Below is the exact data matrix showing what each actor knows vs. what is mathematically concealed from them:

When building out or integrating with this architecture, focus exclusively on these key boundaries: