Turnkey ZKP Integration for Private Transactions

Ethereum's transparency is an asset for some, a barrier for others. When a smart contract publishes every transfer amount on Etherscan, it exposes confidential client data. For corporate settlements, confidential voting, or anonymous transactions, such transparency becomes a blocker. We integrate Zero-knowledge proof so that the blockchain sees only the fact of transaction validity, not its contents. The result is privacy for blockchain transactions while preserving decentralization. Contact us for a project assessment — we will select the optimal scheme.

How ZKP Makes Transactions Private

ZKP is a cryptographic construction where a prover convinces a verifier of a statement's truth without revealing the underlying data. For transactions, this means hiding the amount, addresses, and transfer details. In blockchain, zk-SNARKs (Groth16, PLONK) and zk-STARKs are used. Each system affects the application architecture.

Why Groth16 Is Not Always the Best Choice

Groth16 gives minimal proof size (~200 bytes) and low gas (~300K), but requires a circuit-specific trusted setup — each new scheme needs a separate ceremony. PLONK with a universal SRS is easier to operate, and STARKs require no trusted setup at all, but proof size reaches 200 KB, which is more expensive for on-chain verification. Groth16 saves up to 40% gas compared to PLONK, and in monetary terms for average transaction volumes, it amounts to hundreds of dollars monthly. If deployment speed matters, PLONK can be 2× faster.

The choice depends on the task: for DeFi with frequent transactions, Groth16 saves up to 60% gas but requires a trust setup. PLONK is easier to operate, while STARKs require no setup but have proofs 200× larger.

When to Use ZKP?

ZKP is justified when you need to hide transaction details from the public ledger but maintain verifiability. Typical scenarios: confidential transactions, anonymous voting, private DAOs. Economy of scale: using ZKP reduces blockchain load — a single transaction with a proof consumes as much gas as an ETH transfer but hides all details. This gives up to 80% savings compared to fully encrypting state. In practice, clients save between $2000 and $5000 monthly after implementation.

UTXO-based Approach (Zcash-like)

Funds are stored as notes — encrypted UTXOs. Each transaction consumes old notes and creates new ones. On-chain only a commitment (note hash) and nullifier are stored.

spend(note) → proof(note exists in tree, note not spent, balance >= amount) → reveal nullifier → create new note commitments 

Tornado Cash showed vulnerability to metadata analysis: even with ZKP, timing attacks and amounts deanonymize. ZKP hides transaction links, but not patterns. We add countermeasures — random delays and fixed denominations.

State Encryption via FHE

Fhenix and Inco encrypt state on-chain — smart contracts work with encrypted values. The technology is immature: computational overhead is huge, but it's actively developing.

Tools for ZKP Integration

Circom + SnarkJS

Standard stack for custom circuits:

circuit.circom → compile → R1CS → Powers of Tau → proving key + verification key → verifier.sol 

Example circuit for range proof:

pragma circom 2.1.0;
include "circomlib/circuits/comparators.circom";

template RangeProof(bits) {
    signal input value; // private
    signal input maxValue; // public

    component lt = LessThan(bits);
    lt.in[0] <== value;
    lt.in[1] <== maxValue;
    lt.out === 1;
}

component main {public [maxValue]} = RangeProof(64);

Noir (Aztec)

High-level language similar to Rust. Abstracts away R1CS.

fn main(x: Field, y: pub Field) { assert(x != y); } 

Semaphore

Library for anonymous signals: proves group membership without revealing identity.

semaphore.verifyProof( merkleTreeRoot, nullifierHash, signal, proof ); 

Compliance and Privacy

Vitalik Buterin notes that ZKP allows building selective disclosure — the transaction is private for observers, but the owner can reveal details to a regulator with a cryptographic proof. We implement a viewing key for auditors.

What the Integration Includes

Full scope of work:

• Audit of current architecture and selection of proving system.
• Development and testing of circuits (including 50+ test vectors).
• Integration of smart contract with ZK verifier.
• Prover service (off-chain proof generation supporting up to 1000 requests per minute).
• Documentation and team training.
• Post-launch support for 1 month.

We are a team with 5+ years of experience in ZK development, having completed 30+ projects on private transactions. Request a consultation — we will help select the optimal ZK system.

Process of Work

1. Analysis — determine which data to hide, select scheme (UTXO, commitment, selective disclosure).
2. Circuit design — formalize constraints, verify soundness.
3. Development — write circuits, generate verifier, integrate into smart contract.
4. Audit — static analysis (Circomspect), formal verification, testing on edge cases.
5. Launch — deployment, gas monitoring, prover infrastructure setup.

Timeline Estimates

The specific cost is calculated individually. Contact us — we will prepare a commercial proposal.