Pay once. Unlock credit.
Verified Sepolia payment history is your credit score — no oracle.
spark.sithunyein.com · Help · GitHub · MIT License
Spark makes 15 distinct Attestcoin Protocol surfaces load-bearing across 3 attested event kinds and 5 on-chain entry points:
| Surface | What It Does | Why Needed |
|---|---|---|
verifyAndEmit (0x0FD2) |
BlockProver precompile — proves tx inclusion + continuity | Without it, no Sepolia fact can be verified on Creditcoin |
MerkleProof struct |
Merkle inclusion proof construction | Required by precompile for block inclusion check |
ContinuityProof struct |
Chain continuity proof construction | Ensures source block is genuinely part of the chain |
| Receipt RLP parsing | _parseReceiptLogs() decodes Ethereum receipt on-chain |
Extracts events from proven transaction data |
| Topic matching | Matches event signature from decoded logs | Identifies the correct payment event |
| Amount binding | Extracts amount from proven receipt data | Prevents amount forgery — amount is cryptographically bound |
| 3 event kinds | DepositPaid, RepaymentPaid, BalanceAttested | Most event diversity in the hackathon |
| Parallel dual proofs | Two proofs generated simultaneously | Avoids sequential 16-20 min wait |
ProofBuilder SDK |
Off-chain proof generation via @gluwa/usc-sdk | Assembles Merkle + continuity proofs |
waitUntilHeightAttested |
Polls until source block is attested | Required before proof generation |
| ChainInfo (0x0FD3) | Reads supported chains + attested heights | Discovers protocol state, explains attestation lag |
previewIngest |
Dry-run proof validation (staticcall) | Saves gas by checking validity before submitting |
executeBatch |
Atomic multi-proof verification | Batch N proofs in one tx, all-or-nothing |
getBatchProof (SDK) |
Batch proof generation via @gluwa/usc-sdk | Generate multiple proofs atomically in one SDK call |
Unique to Spark: Dual proofs verify both payment AND solvency. The balance attestation (kind 3) proves the borrower holds sufficient funds — no other project in this hackathon verifies solvency.
Full surface enumeration: docs/ATTESTCOIN_SURFACE.md
2.5 billion people worldwide cannot access credit because they lack bank history, documentation, or infrastructure. Even in crypto, cross-chain credit requires trusting a middleman to verify what happened on another chain. That single point of failure defeats the purpose of decentralization.
Current solutions have three fundamental flaws:
- Oracles require trust. A centralized price feed or attestation service can be manipulated, censored, or go offline. The borrower has no guarantee the oracle reports honestly.
- Bridges are single points of failure. Bridges have been drained for billions. Moving assets cross-chain to prove creditworthiness exposes the borrower to bridge exploits.
- Self-reported history is worthless. A borrower can open and repay their own loan 100 times to build a perfect score. Without a real counterparty, payment history proves nothing.
Spark solves all three by using the Attestcoin Protocol to cryptographically verify Sepolia payments on Creditcoin — no oracle, no bridge, no trust. And critically, Spark's dual proofs verify not just that a payment happened, but that the borrower has the funds to cover the credit (solvency check). No other project in this hackathon verifies solvency.
Spark proves Sepolia payments with Attestcoin (USC / BlockProver), then opens or clears credit on Creditcoin testnet. No bank forms, no centralized price oracle.
- Pay deposit on Sepolia → dual Attestcoin proofs (deposit + ETH balance) → open credit on Creditcoin
- Credit score from on-chain attested payment history (650–850)
- LTV bonus from linked history (+2.5% at ≥1 payment, +5% at ≥3) plus balance-based LTV
- Withdraw sCREDIT, redeem against debt, repay on Sepolia to close
Live app: https://spark.sithunyein.com · Deck: deck.pdf
Pay deposit → Verify (Attestcoin ~8–20 min) → Withdraw → Redeem → Repay → Closed
Optional first: link past Sepolia payments on Credit score to raise score and LTV before opening a new line.
flowchart TB
User[Borrower] --> App[Spark App]
App --> Pay[SepoliaPayment]
App --> Prover[Attestcoin Proof API]
Prover --> Verifier[AttestcoinPaymentVerifier]
Verifier --> Credit[CreditLine]
Credit --> Token[SparkCredit sCREDIT]
See docs/architecture.md and docs/attestcoin.md.
Full repo layout (excluding node_modules/, .next/, contracts/lib/ vendored deps):
spark/
├── .env.example # Root env template (optional)
├── .gitignore
├── .gitmodules # forge-std submodule
├── package.json # Root scripts: dev, build, test:contracts
├── README.md
├── LICENSE
├── SECURITY.md
├── CONTRIBUTING.md
│
├── brand/ # Logo source (copied into app/public/brand/)
│ ├── logo.png
│ ├── logo-mark.svg
│ ├── logo-on-orange.png
│ ├── logo-on-orange.svg
│ ├── logo-wordmark-dark.svg
│ └── logo-wordmark-light.svg
│
├── docs/
│ ├── addresses.md # Production + legacy contract addresses & Vercel env
│ ├── architecture.md # System diagram, sequences
│ ├── attestcoin.md # USC / BlockProver integration
│ ├── ATTESTCOIN_SURFACE.md # Every Attestcoin surface Spark uses, why needed
│ ├── THREAT_MODEL.md # What attacks are prevented, what is still open
│ ├── SCORING.md # Credit score formula, LTV bonus, constants rationale
│ ├── evidence/ # On-chain proof artifacts
│ ├── deck.md # Pitch deck notes
│ └── deploy-vercel.md # Vercel deploy (root dir = app)
│
├── app/ # Next.js 15 — Vercel root directory
│ ├── .env.example # Local / production env template
│ ├── .gitignore
│ ├── package.json
│ ├── pnpm-lock.yaml
│ ├── next.config.ts
│ ├── next-env.d.ts
│ ├── tsconfig.json
│ ├── postcss.config.js
│ ├── tailwind.config.js
│ │
│ ├── public/
│ │ ├── favicon.svg
│ │ ├── favicon.png
│ │ ├── deck.pdf
│ │ ├── deck.html
│ │ └── brand/
│ │ ├── logo.png
│ │ ├── logo-mark.svg
│ │ ├── logo-on-orange.png
│ │ ├── logo-on-orange.svg
│ │ ├── logo-wordmark-dark.svg
│ │ ├── logo-wordmark-light.svg
│ │ └── metamask.png
│ │
│ └── src/
│ ├── styles/
│ │ └── globals.css
│ │
│ ├── app/ # App Router
│ │ ├── layout.tsx # Root layout, providers
│ │ ├── page.tsx # / → redirect overview
│ │ ├── overview/page.tsx # Dashboard, score, position, checklist
│ │ ├── pay/page.tsx # Sepolia deposit + Attestcoin verify + openCredit
│ │ ├── score/page.tsx # Link history → creditScore + LTV bonus
│ │ ├── withdraw/page.tsx # Withdraw + redeem sCREDIT
│ │ ├── transfer/page.tsx # Send & receive sCREDIT
│ │ ├── repay/page.tsx # Sepolia repay + verify + close
│ │ ├── activity/page.tsx # Payment journal (sidebar: Payments)
│ │ ├── help/page.tsx # User guide
│ │ ├── settings/page.tsx # Wallet, networks, security
│ │ └── advanced/page.tsx # Developer / contract links
│ │
│ ├── components/
│ │ ├── AppShell.tsx # Page shell + sidebar
│ │ ├── Sidebar.tsx # Nav: overview, pay, score, withdraw, …
│ │ ├── Logo.tsx
│ │ ├── ConnectButton.tsx
│ │ ├── ConnectModal.tsx
│ │ ├── AccountMenu.tsx
│ │ ├── MetricCard.tsx
│ │ ├── PositionSnapshot.tsx
│ │ ├── ActivityTable.tsx
│ │ ├── OnboardingChecklist.tsx
│ │ ├── ConfirmingStages.tsx # Pay/repay stepper
│ │ ├── AttestcoinProofPanel.tsx
│ │ ├── LinkHistoryPanel.tsx # Credit score linking UI
│ │ ├── SuccessBanner.tsx
│ │ ├── PaymentHistoryStrip.tsx
│ │ └── SimpleChart.tsx
│ │
│ ├── hooks/
│ │ ├── usePaymentActivity.ts # Journal + Sepolia log scan
│ │ └── useChainTxConfirmation.ts
│ │
│ └── lib/
│ ├── config.ts # NEXT_PUBLIC_* addresses & RPC
│ ├── abi.ts # Contract ABIs
│ ├── wagmi.tsx # MetaMask connector, Creditcoin chain
│ ├── sparkInjected.js # Custom injected connector
│ ├── sparkInjected.d.ts
│ ├── usc.ts # Attestcoin proof builder (parallel waits)
│ ├── chains.ts # ensureCreditcoinChain / ensureSepoliaChain
│ ├── errors.ts # friendlyError messages
│ ├── flowState.ts # sessionStorage pay/repay resume
│ └── format.ts # ETH formatting, proof encoding
│
└── contracts/ # Foundry
├── foundry.toml
├── foundry.lock
├── remappings.txt
├── lib/
│ └── forge-std/ # Git submodule
│
├── src/
│ ├── SepoliaPayment.sol # payDeposit, payRepayment, attestBalance
│ ├── CreditLine.sol # openCredit, score, history bonus, redeem, repay
│ ├── AttestcoinPaymentVerifier.sol
│ ├── SparkCredit.sol # sCREDIT ERC-20
│ ├── MockPaymentVerifier.sol # Unit tests only
│ └── interfaces/
│ └── IPaymentVerifier.sol
│
├── test/
│ └── Spark.t.sol # 300 tests: score, history, dual-proof, batch, negative-path, edge cases, stress, lifecycle, events, combos
│
├── script/
│ └── Deploy.s.sol
│
└── scripts/
├── deploy-all.sh
├── deploy-attestcoin.ps1
├── attestcoin-ctor-args.txt
└── creditline-ctor-args.txt
| Contract | Network | Address | Verified |
|---|---|---|---|
| SepoliaPayment | Ethereum Sepolia | 0x63F0c69cf9F8b53E8eDD141d07fF2eEd2237ccc4 |
Yes (Blockscout) |
| AttestcoinPaymentVerifier | Creditcoin testnet | 0xF13205Bdf48A3159d4A46309C639930aE8faC130 |
Yes |
| CreditLine (history + score + LTV bonus) | Creditcoin testnet | 0x2C3585019B957b16459C409f34973b583267C742 |
Yes (Blockscout) |
| SparkCredit (sCREDIT) | Creditcoin testnet | 0x1BaDE07F2F3295528a2F7316119813b6846dFfaD |
Yes |
| BlockProver (USC precompile) | Creditcoin | 0x0000000000000000000000000000000000000FD2 |
n/a |
| Contract | Network | Address |
|---|---|---|
| SepoliaPayment | Ethereum Sepolia | 0x4B137F56A0b5A8633D079d2d6b34d6aC5CdD22E9 |
| AttestcoinPaymentVerifier | Creditcoin testnet | 0x372BF96DFfa019A03E861d57CfC8a129172C8A3C |
| CreditLine (dual-proof + interest) | Creditcoin testnet | 0x1Ba750b08dC4C06B993DfDedE45d22cbD540D319 |
| SparkCredit (sCREDIT) | Creditcoin testnet | 0xFa18A5458a973a4E8a3eF327A88262683B64b02b |
Retired stacks and Vercel env values: docs/addresses.md.
On-chain demo wallet: 0x7A35f63F81357DaDE2cff8f5699b935786Aa9Da2. All txs below are on the production CreditLine (0x2C358501…) with real Attestcoin USC proofs (BlockProver TransactionVerified in each tx).
CreditOpened: deposit 0.01 ETH, attested balance ~0.357 ETH, credit 0.0095 ETH, factorBps = 9500 (95% LTV — base 90% + 500 bps history bonus at ≥3 linked payments).
5 AttestedPaymentLinked events on production CreditLine (kinds 1 = deposit, 2 = repayment). On-chain creditScore() = 850 (650 base + 5 × 40).
| # | Kind | Creditcoin tx |
|---|---|---|
| 1 | deposit | 0xe5ec5506…da9c1 |
| 2 | repayment | 0xe7313fef…9f15 |
| 3 | repayment | 0x5092e516…18eb4 |
| 4 | deposit | 0xbbec27e6…a618 |
| 5 | repayment | 0x5fc0b4fb…e122 |
Full log index: CreditLine events.
Both loops use real USC proofs end-to-end. Sepolia repay txs linked at close via CreditClosed.
Loop 1 — Aug 13 (factorBps = 9000, credit 0.009 ETH)
| Step | Creditcoin tx |
|---|---|
| Open | 0xe5ec5506…da9c1 |
| Withdraw | 0xbf411c5a…1f3d |
| Redeem | 0x48980365…cfb01 |
| Repay + close | 0x5092e516…18eb4 |
Loop 2 — Aug 14 (factorBps = 9500, credit 0.0095 ETH)
| Step | Creditcoin tx |
|---|---|
| Open | 0xbbec27e6…a618 |
| Withdraw | 0x3bc160b1…2789 |
| Redeem | 0x9177c410…d34d |
| Repay + close | 0x5fc0b4fb…e122 |
Sepolia repayments (kind-2 USC proofs consumed at close):
- Loop 1:
0x5fa5d7a2…9785 - Loop 2:
0xf3825f7f…ebe6
# Install (from repo root)
pnpm install --dir app
# Contracts
cd contracts && forge test
# App
cd ../app
cp .env.example .env.local # fill RPC URLs if needed
pnpm devOpen http://localhost:3000. User guide: in-app Help or spark.sithunyein.com/help.
| Target | How |
|---|---|
| App | Vercel, root directory app — docs/deploy-vercel.md |
| Contracts | Foundry contracts/script/Deploy.s.sol → update docs/addresses.md + Vercel env |
| Metric | Rule |
|---|---|
| Score | 650 base + 40 × attested payments (cap 850) |
| LTV bonus | +250 bps (≥1 payment), +500 bps (≥3 payments) |
| Balance LTV | ≥2× deposit → 90%, ≥1× → 85%, else 80% base |
| Proof | submitAttestedPayment links past Sepolia txs; openCredit / repayCredit also count |
Formula lives in contracts/src/CreditLine.sol — readable via creditScore() and getHistory().
| Phase | Focus |
|---|---|
| Now | Live testnet: dual Attestcoin proofs, score, history LTV, strict receipt log decoding with amount binding, full borrow/repay loop |
| Next | Faster verify UX (parallel attestation, caching) |
| Later | Mainnet, audit, lending pool, single-network UX |
Not audited. Testnet only. See SECURITY.md. No private keys on Vercel.
Verifier note: BlockProver proves inclusion cryptographically. The adapter now strictly decodes the receipt RLP from the proven encodedTransaction, matching event topic, indexed payer, and non-indexed amount from decoded logs. Amount is cryptographically bound (not trusting claim.amount). Per the Aug 18 AMA, receipt log data is confirmed available via BlockProver.
Spark includes 8 live negative-path tests against the real BlockProver precompile on CC3 testnet. These use eth_call (read-only) — zero gas, zero CTC, zero cost.
cd contracts && bash run-negative-paths.shResults:
- Forged merkle root → REJECTED
- Wrong chain key (99) → REJECTED
- Zero height → REJECTED
- Empty encoded transaction → REJECTED
- Mismatched sibling lengths → REJECTED
- Very large chain key (9999) → REJECTED
- Max uint64 height → REJECTED
- Random bytes as proof → REJECTED
All 8 forged proofs rejected by the real BlockProver precompile. Judges can run this themselves.
MIT — LICENSE.