Smart Contracts

Onchain escrow and proof verification

Onchain Architecture

zkGrants smart contracts handle three core functions: holding funds in escrow, verifying zkTLS proofs, and releasing payouts to verified claimants. The same conceptual model applies to both Ethereum and Solana.

Escrow

Lock funds at creation

Verify

Validate zkTLS proofs

Release

Pay verified claims

Grant State Machine

Each grant escrow follows a common state machine:

CreatedFundedClaimablePaid
CreatedGrant metadata committed onchain; rules and parameters fixed
FundedAward locked in escrow; 4% fee allocated to treasury
ClaimableEligible submission exists (tracked offchain via GitHub events)
PaidProof verified; funds released to recipient
Refunded(Alternative) Conditions met for refund; funds returned to grantor

Ethereum (EVM)

Ξ

Solidity Contracts

EVM-compatible deployment

GrantFactory

Factory contract for creating new grant escrow instances. Optionally, grants can be created directly without a factory.

createGrant(params) → grantId

GrantEscrow

Holds funds, verifies proofs, releases payouts, handles refunds.

fundGrant(grantId, amount)claim(grantId, recipient, proof)refund(grantId)

Verifier

zkTLS proof verification contract. Called by GrantEscrow during claim.

verify(proof, publicInputs) → bool

Supported Assets

ETH (native) • USDC (ERC-20) • USDT (ERC-20) • Other ERC-20 tokens

Solana

◎

Native Rust Programs

High-performance Solana programs

zkgrants_program

Native Rust program managing grant accounts, escrow vaults, claim verification, and refunds. Built without frameworks for maximum performance and control.

create_grant(...)fund_grant(...)submit_claim(proof_data)refund_grant(...)

Account Structure

Program Derived Addresses (PDAs) for Grant, Vault, and Claim accounts. Each grant has its own vault PDA holding escrowed funds.

Light Protocol Groth16 Verifier

Proof verification uses Light Protocol's Groth16 verifier for efficient onchain ZK proof verification on Solana. This enables cost-effective verification of SP1-generated proofs.

Supported Assets

SOL (native) • USDC (SPL) • USDT (SPL) • Other SPL tokens

Security Considerations

Proof Binding

Proofs include grantId, chainId, and recipient address to prevent replay attacks and front-running.

Immutable Rules

Grant parameters (deadline, refund policy, etc.) are fixed at creation and cannot be changed after funding.

Minimal Admin Keys

Contracts are designed to minimize privileged roles. Verifiers are immutable where possible.

Single-Claim Enforcement

Grants track claimed status to prevent double-claims on the same escrow.

Related Topics

Learn more about proof generation and the API for interacting with zkGrants.

zkTLS ProofsAPI Reference