Aura Vault Protocol

A production-ready, share-based yield vault smart contract built on Soroban for the Stellar ecosystem.

Overview

Aura solves fragmented liquidity and manual yield compounding in Soroban DeFi. It aggregates deposits of a single SEP-41-compatible underlying token, issues proportional vault shares to depositors, and auto-compounds yield through permissionless keeper harvests — all in a trust-minimized, no_std on-chain environment.

How It Works

• Deposit — Transfer underlying tokens into the vault and receive shares proportional to your contribution. First depositor gets a 1:1 seed ratio; subsequent depositors get floor(amount × total_shares / total_assets) shares.
• Withdraw — Burn your shares to redeem floor(shares × total_assets / total_shares) underlying tokens, including any accrued yield.
• Harvest — Any keeper injects yield tokens into the vault without minting new shares, increasing the exchange rate for all existing shareholders.
• View — total_assets and balance_of are gas-free read-only calls.

Architecture

aura-vault/
├── Cargo.toml
└── src/
    ├── lib.rs        # AuraVault contract — initialize, deposit, withdraw, harvest, views
    ├── errors.rs     # VaultError (8 typed variants)
    ├── storage.rs    # DataKey, TTL constants, get/set/bump helpers
    ├── interface.rs  # AuraVaultTrait public ABI
    └── test.rs       # 22 unit + integration tests

Security Properties

• Checks-Effects-Interactions (CEI) ordering on every mutating function
• Inflation attack prevention — zero-share mint rejection fence
• Overflow safety — all arithmetic uses checked_mul / checked_div; overflow-checks = true in release profile
• No unwrap() / expect() outside #[cfg(test)]
• Soroban archival safety — TTL extended on every mutating call (30-day lifetime, 7-day threshold)
• Flash loan guard — deposit, withdraw, and harvest verify that the vault's actual on-chain token balance equals total_deposited before executing; any discrepancy emits a suspicious event and returns BalanceMismatch
• Emergency pause — admin can call pause() to halt all mutating operations (deposit, withdraw, harvest); unpause() resumes; current state readable via is_paused()
• Event logging — deposit, withdraw, harvest, pause, unpause, and upgrade all emit typed events; balance mismatches emit a suspicious event with observed vs. tracked amounts

Building

Requires Rust with the wasm32-unknown-unknown target:

rustup default stable
rustup target add wasm32-unknown-unknown

cd aura-vault
cargo test                                              # run all 22 tests
cargo build --target wasm32-unknown-unknown --release   # build deployable Wasm

The compiled binary will be at:

aura-vault/target/wasm32-unknown-unknown/release/aura_vault.wasm

Deployment (Stellar Testnet / Mainnet)

# Upload Wasm
stellar contract upload \
  --wasm target/wasm32-unknown-unknown/release/aura_vault.wasm \
  --source <your-keypair> \
  --network testnet

# Deploy instance
stellar contract deploy \
  --wasm-hash <hash-from-upload> \
  --source <your-keypair> \
  --network testnet

# Initialize
stellar contract invoke \
  --id <contract-id> \
  --source <admin-keypair> \
  --network testnet \
  -- initialize \
  --admin <admin-address> \
  --underlying_token <token-contract-id>

Contract Interface

Function	Description
initialize(admin, underlying_token)	One-time setup; stores admin and token address
deposit(caller, amount)	Mint shares proportional to deposit
withdraw(caller, shares)	Burn shares and redeem underlying tokens
harvest(caller, yield_amount)	Inject yield without minting shares
pause()	Admin-only: halt all mutating operations
unpause()	Admin-only: resume operations
is_paused()	Read current pause state
total_assets()	Read current total underlying tokens in vault
balance_of(address)	Read share balance for any address

Error Codes

Code	Variant	Trigger
1	NotInitialized	Vault not yet initialized
2	AlreadyInitialized	initialize called more than once
3	InsufficientShares	Withdraw amount exceeds caller's balance
4	InsufficientUnderlying	Vault cannot cover redemption
5	ZeroAmount	Zero or negative input; or share mint rounds to zero
6	MathOverflow	Arithmetic overflow in share formula
7	InvalidAddress	Reserved for future address validation
8	ZeroShares	Harvest called when total shares is zero
9	UpgradeUnauthorized	Caller is not the admin
10	StorageLayoutMismatch	On-chain layout version mismatch on upgrade
11	VaultPaused	Mutating operation called while vault is paused
12	BalanceMismatch	Actual token balance differs from tracked state (flash loan guard)

License

MIT