There are applications that are literally impossible to build on a public blockchain without Fully Homomorphic Encryption. Not "hard to build." Not "possible with workarounds." Impossible.
Here are five of them. Each one is buildable today with the Aura SDK.
1. A Sealed-Bid Auction Where Nobody Can Cheat
On-chain auctions today are fundamentally broken. If bids are public, participants can see each other's bids — sniping at the last second, or colluding to keep bids low. Commit-reveal schemes have 60-70% reveal rates and still don't hide bid values during winner computation.
The FHE solution: Each bidder encrypts their bid. The auction contract uses homomorphic comparison to determine the winner without decrypting any bids. Only the winning bid is revealed via threshold decryption.
const encryptedBid = await aura.encrypt(myBidAmount, auctionPublicKey);
await auctionProgram.submitBid(encryptedBid);
// Winner computed homomorphically — no bids ever decrypted during comparisonWhy this matters: NFT auctions, treasury bond auctions, ad slot auctions, domain name auctions.
2. A Dark Pool DEX With Verifiable Execution
Large traders need to execute without moving the market. In DeFi, every large order is visible before execution. Existing "dark pool" DEXs use off-chain matching — reintroducing trust assumptions.
The FHE solution: Orders are encrypted client-side. The matching engine runs homomorphically on encrypted prices and quantities. The matching is verifiable but order flow is never exposed in plaintext.
const order = await aura.encryptOrder({
side: 'buy',
price: 150_00n, // encrypted
quantity: 100n, // encrypted
token: SOL_MINT,
});
await darkPoolProgram.placeOrder(order);Why this matters: Institutional adoption is blocked by MEV and information leakage. A verifiable on-chain dark pool is the first design giving institutions privacy without sacrificing transparency guarantees.
3. Private Credit Scoring On-Chain
DeFi lending is either overcollateralized (capital-inefficient) or relies on off-chain credit — reintroducing TradFi trust. On-chain credit scoring would unlock capital-efficient lending, but borrowers won't expose financial history publicly.
The FHE solution: A borrower encrypts their financial data. The scoring model runs homomorphically — computing a credit score from encrypted inputs. Only the score (not underlying data) is threshold-decrypted.
const encryptedHistory = await aura.encrypt(financialData, lenderPublicKey);
const encryptedScore = await creditProgram.computeScore(encryptedHistory);
// Only the final score is decrypted — raw data never exposedWhy this matters: The bridge between DeFi and real-world lending. Under-collateralized loans at scale without doxxing borrowers.
4. Private DAO Governance That Prevents Vote Buying
On-chain voting is transparent. This enables vote buying (you can prove how you voted, so someone can pay you) and strategic voting (voting last after seeing everyone else). Both undermine governance.
The FHE solution: Voters encrypt their vote and voting weight. The tally runs homomorphically — summing encrypted votes. The result is threshold-decrypted only after voting closes.
const encryptedVote = await aura.encrypt(myVote, daoPublicKey);
const encryptedWeight = await aura.encrypt(myTokenBalance, daoPublicKey);
await govProgram.castVote(encryptedVote, encryptedWeight);
// After voting period: homomorphic tally + threshold revealWhy this matters: Every DAO with treasury value needs this. Vote buying becomes impossible because you cannot prove how you voted.
5. Encrypted Gaming State (Fog of War, Hidden Hands, Private Inventories)
On-chain games cannot have hidden information. In a card game, your hand is readable by anyone. This eliminates entire genres from being feasible on-chain.
The FHE solution: Game state private to each player is stored as FHE ciphertexts. Game logic runs homomorphically. Results are decrypted only to the parties who should see them.
const encryptedHand = await aura.encrypt(myCards, myPublicKey);
const encryptedResult = await gameProgram.resolveBattle(
player1EncryptedUnits,
player2EncryptedUnits
);
// Each player decrypts only their own outcomeWhy this matters: On-chain gaming is a multi-billion dollar sector held back by transparency constraints. FHE removes that constraint entirely.
Build One of These
The SDK launches April 7. Alpha access (10 builder spots with direct engineering support) opens April 24. Apply at afhe.io/builders.
Grants available: $1K-$5K (PoC) · $5K-$25K (working app) · $25K-$100K (full protocol). Details at afhe.io/grants.