# Proof of Reserve Oracle

[DIA oracles](https://www.diadata.org/) helped to deliver Lightning Network node balance data to Ethereum, enabling `strBTC` holders to verify their Bitcoin backing on-chain.

### 1. Oracle Details

#### 1.1. Reserve Feeds

The reserve feeds are consumable via the adapter contract tracking on-chain & off-chain reserves.

| Reserve Query Key | Reserve Oracle Address (Combined Reserves)                                                                            | Adapter Address (Chainlink-Compatible)                                                                                |
| ----------------- | --------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------- |
| STROOM-Reserves   | [0x12DB8fcA6AAA29E922bFAD8a7771aE11F17a1811](https://etherscan.io/address/0x12DB8fcA6AAA29E922bFAD8a7771aE11F17a1811) | [0x1d18b5147B11908B24A247517F606c0705CF8d40](https://etherscan.io/address/0x1d18b5147b11908b24a247517f606c0705cf8d40) |

#### 1.2. Contracts

The DIAOracleV2 contract calculates the off-chain reserves.

<table><thead><tr><th width="233.8570556640625">Blockchain</th><th>Address</th></tr></thead><tbody><tr><td><strong>Ethereum Mainnet</strong></td><td><a href="https://etherscan.io/address/0xFe0593fA61c7Cf3D2CD17b8B53Ef844A33b0463d">0xFe0593fA61c7Cf3D2CD17b8B53Ef844A33b0463d</a></td></tr></tbody></table>

#### 1.3. Oracle Configuration

Settings that dictate how the oracle computes and updates data.

<table><thead><tr><th width="289.28564453125">Setting</th><th>Rate</th></tr></thead><tbody><tr><td><strong>Deviation (%) &#x26; Refresh Frequency</strong></td><td>0.5% and 120 seconds</td></tr><tr><td><strong>Heartbeat</strong></td><td>24h</td></tr></tbody></table>

#### 1.4. Oracle Configuration

**1.4.1. On-chain Sources**

<table><thead><tr><th width="152.42840576171875">Contract</th><th width="272">Asset Address</th><th>Owner Address</th></tr></thead><tbody><tr><td>wBTC &#x3C;-> strBTC converter</td><td><a href="https://etherscan.io/token/0x2260fac5e5542a773aa44fbcfedf7c193bc2c599">0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599</a></td><td><a href="https://etherscan.io/address/0x56192f14c1d84e41db3d5d4c5d407efdb5cb1352">0x56192F14C1d84e41Db3d5d4C5d407EFDB5CB1352</a></td></tr><tr><td>cbBTC &#x3C;-> strBTC converter</td><td><a href="https://etherscan.io/token/0xcbb7c0000ab88b473b1f5afd9ef808440eed33bf">0xcbB7C0000aB88B473b1f5aFd9ef808440eed33Bf</a></td><td><a href="https://etherscan.io/address/0xe7b4c44adb17147ad877eb8607eeb1e95adf2cd0">0xe7b4c44adB17147Ad877EB8607EEB1e95AdF2cD0</a> </td></tr></tbody></table>

**1.4.2. Off-chain Sources**

<table><thead><tr><th width="197.28564453125">Lightning Service</th><th>Query Endpoints</th><th data-hidden></th></tr></thead><tbody><tr><td><a href="https://api.lightning.community/api/lnd/lightning/wallet-balance/index.html">WalletBalance</a></td><td>Return <code>total_balance</code></td><td></td></tr><tr><td><a href="https://api.lightning.community/api/lnd/lightning/channel-balance/index.html">ChannelBalance</a></td><td>Return the sum of <code>local_balance</code>, <code>unsettled_local_balance</code>,&#x26; <code>pending_open_local_balance</code></td><td></td></tr><tr><td><a href="https://api.lightning.community/api/lnd/lightning/pending-channels/index.html">PendingChannels</a></td><td>Return <code>total_limbo_balance</code></td><td></td></tr></tbody></table>

### 2. How the Oracle Works

The DIA adapter (DIAStroomAdapter) calculates the total BTC reserves by combining two data sources:&#x20;

1. On-chain reserves: the sum of WBTC and cbBTC balances from Stroom converter contract addresses on Ethereum.
2. Off-chain reserves: the sum of WalletBalance API (total\_balance) and ChannelBalance API (local\_balance + unsettled\_local\_balance + pending\_open\_local\_balance) with 8-decimal satoshi precision. The DIA oracle (DIAOracleV2) pushes the aggregated off-chain reserves value on-chain when they deviate by 0.5% or every 24 hours, as configured.

### 3. How to Access Data

#### 3.1. DIAStroomAdapter (Solidity)

The following is the list of available methods on the `DIAStroomAdapter` contract.

**3.1.1. getOnchainReserve()**

| function getOnchainReserve() public view returns (uint256) |
| ---------------------------------------------------------- |

Calculates the total on-chain BTC reserves by aggregating WBTC and cbBTC balances from Stroom converter contract addresses on Ethereum.

Return Value (uint256): The total on-chain BTC reserves in 8 decimals.

**3.1.2. getOffchainReserve()**

| function getOffchainReserve() public view returns (uint256) |
| ----------------------------------------------------------- |

Makes a \`getValue()\` call to the DIA oracle, which in turn aggregates off-chain BTC reserves by querying Lightning API services. The DIA oracle's methodology combines \`total\_balance\` from WalletBalance API with the sum of \`local\_balance\`, \`unsettled\_local\_balance\`, and \`pending\_open\_local\_balance\` from ChannelBalance API.

Return Value (uint256): The total off-chain BTC reserves in 8 decimals.

**3.1.3. getCombinedReserveValue()**

| function getCombinedReserveValue() public view returns (uint256) |
| ---------------------------------------------------------------- |

Returns the sum of both on-chain and off-chain BTC reserves.

Return Value (uint256): The total combined BTC reserves in 8 decimals.

#### 3.2. Adapter contracts

To consume price data from the oracle, you can use the adapter smart contract for the [reserve feed](#id-1.1.-reserve-feeds). This will allow you to access the same methods on the \`AggregatorV3Interface\` such as \`latestAnswer\` & \`latestRoundData\`. You can learn more [here](https://www.diadata.org/docs/guides/how-to-guides/migrate-to-dia).

### 4. Glossary

<table><thead><tr><th width="184.71417236328125">Term</th><th>Definition</th></tr></thead><tbody><tr><td>Deviation</td><td>The percentage threshold that triggers a price update when exceeded</td></tr><tr><td>Refresh frequency</td><td>A time interval for checking and updating prices if certain conditions are met</td></tr><tr><td>Heartbeat</td><td>A forced price update at a fixed interval</td></tr></tbody></table>