[rushikeshgarad2024-dev]

Summary

Resolves #347 (Wave Issue Key: ZK-071).

Context & Implementation

This PR explicitly separates the full withdrawal circuit schema from the reduced contract verifier payload to eliminate schema confusion and prevent runtime layout mismatch between off-chain witness generation and on-chain verification.

1. Explicit Schema & Type Separation in SDK (sdk/src/public_inputs.ts, sdk/src/proof.ts):

   • CIRCUIT_PUBLIC_INPUT_SCHEMA / WITHDRAWAL_PUBLIC_INPUT_SCHEMA: Defined with all 8 fields: [pool_id, root, nullifier_hash, recipient, amount, relayer, fee, denomination], frozen against runtime mutation.
   • CONTRACT_VERIFIER_INPUT_SCHEMA: Defined with the exact 6 reduced fields: [root, nullifier_hash, recipient, amount, relayer, fee], frozen.
   • Distinct TypeScript interfaces: WithdrawalCircuitPublicInputs, FullWithdrawalCircuitPublicInputs, ContractVerifierPublicInputs.
   • Deterministic projection: deriveContractVerifierInputs(full: WithdrawalCircuitPublicInputs): ContractVerifierPublicInputs with full input validation (rejects missing fields, no silent drops).
   • Serialization: serializeContractVerifierInputs emits 6 canonical field hexes (192 bytes).
   • Formatting helper: ProofGenerator.formatContractVerifierPayload.

2. Soroban Contract Verifier Support (contracts/privacy_pool/src/types/state.rs, contracts/privacy_pool/src/crypto/verifier.rs):

   • CircuitPublicInputs (8 fields) and ContractVerifierPublicInputs (6 fields) with explicit projection CircuitPublicInputs::to_contract_verifier_inputs(&self).
   • compute_vk_x accepts 6 contract verifier inputs; compute_vk_x_circuit accepts 8 circuit inputs.
   • Verifier dynamically checks IC length (EXPECTED_IC_VECTOR_LENGTH = 7 for 6 inputs, or 9 for 8 inputs) and validates structural field boundaries.

3. Validation & Test Suite:

   • test/schema_parity.test.ts updated to enforce distinct schemas, 6-input contract verifier schema, explicit exclusion of pool_id and denomination from contract verifier, and deterministic derivation.
   • Unit test test_circuit_public_inputs_to_contract_verifier_inputs_projection added to state_test.rs.
   • SDK builds cleanly (npm run build) and schema parity tests pass 100%.

Stellar Payout Address

Stellar Address: GC5U46IS25KYFKNHDXEHR3KTQB3DVIBM4NW5BH4MVUE2G77STCJP4IHF