Wallets

Wallets

Library responsible for handling integration between Bridge contract and ECDSA wallets.

WalletState

enum WalletState {
  Unknown,
  Live,
  MovingFunds,
  Closing,
  Closed,
  Terminated
}

Wallet

struct Wallet {
  bytes32 ecdsaWalletID;
  bytes32 mainUtxoHash;
  uint64 pendingRedemptionsValue;
  uint32 createdAt;
  uint32 movingFundsRequestedAt;
  uint32 closingStartedAt;
  uint32 pendingMovedFundsSweepRequestsCount;
  enum Wallets.WalletState state;
  bytes32 movingFundsTargetWalletsCommitmentHash;
}

NewWalletRequested

event NewWalletRequested()

NewWalletRegistered

event NewWalletRegistered(bytes32 ecdsaWalletID, bytes20 walletPubKeyHash)

WalletMovingFunds

event WalletMovingFunds(bytes32 ecdsaWalletID, bytes20 walletPubKeyHash)

WalletClosing

event WalletClosing(bytes32 ecdsaWalletID, bytes20 walletPubKeyHash)

WalletClosed

event WalletClosed(bytes32 ecdsaWalletID, bytes20 walletPubKeyHash)

WalletTerminated

event WalletTerminated(bytes32 ecdsaWalletID, bytes20 walletPubKeyHash)

requestNewWallet

function requestNewWallet(struct BridgeState.Storage self, struct BitcoinTx.UTXO activeWalletMainUtxo) external

Requests creation of a new wallet. This function just forms a request and the creation process is performed asynchronously. Outcome of that process should be delivered using registerNewWallet function.

Requirements:

• activeWalletMainUtxo components must point to the recent main UTXO of the given active wallet, as currently known on the Ethereum chain. If there is no active wallet at the moment, or the active wallet has no main UTXO, this parameter can be empty as it is ignored,

• Wallet creation must not be in progress,

• If the active wallet is set, one of the following conditions must be true:

• The active wallet BTC balance is above the minimum threshold and the active wallet is old enough, i.e. the creation period was elapsed since its creation time,

• The active wallet BTC balance is above the maximum threshold.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
activeWalletMainUtxo	struct BitcoinTx.UTXO	Data of the active wallet's main UTXO, as currently known on the Ethereum chain.

registerNewWallet

function registerNewWallet(struct BridgeState.Storage self, bytes32 ecdsaWalletID, bytes32 publicKeyX, bytes32 publicKeyY) external

Registers a new wallet. This function should be called after the wallet creation process initiated using requestNewWallet completes and brings the outcomes.

Requirements:

• The only caller authorized to call this function is registry,

• Given wallet data must not belong to an already registered wallet.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
ecdsaWalletID	bytes32	Wallet's unique identifier.
publicKeyX	bytes32	Wallet's public key's X coordinate.
publicKeyY	bytes32	Wallet's public key's Y coordinate.

notifyWalletRedemptionTimeout

function notifyWalletRedemptionTimeout(struct BridgeState.Storage self, bytes20 walletPubKeyHash, uint32[] walletMembersIDs) internal

Handles a notification about a wallet redemption timeout. Triggers the wallet moving funds process only if the wallet is still in the Live state. That means multiple action timeouts can be reported for the same wallet but only the first report requests the wallet to move their funds. Executes slashing if the wallet is in Live or MovingFunds state. Allows to notify redemption timeout also for a Terminated wallet in case the redemption was requested before the wallet got terminated.

Requirements:

• The wallet must be in the Live, MovingFunds, or Terminated state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.
walletMembersIDs	uint32[]	Identifiers of the wallet signing group members.

notifyWalletHeartbeatFailed

function notifyWalletHeartbeatFailed(struct BridgeState.Storage self, bytes32 publicKeyX, bytes32 publicKeyY) external

Handles a notification about a wallet heartbeat failure and triggers the wallet moving funds process.

Requirements:

• The only caller authorized to call this function is registry,

• Wallet must be in Live state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
publicKeyX	bytes32	Wallet's public key's X coordinate.
publicKeyY	bytes32	Wallet's public key's Y coordinate.

notifyWalletCloseable

function notifyWalletCloseable(struct BridgeState.Storage self, bytes20 walletPubKeyHash, struct BitcoinTx.UTXO walletMainUtxo) external

Notifies that the wallet is either old enough or has too few satoshis left and qualifies to be closed.

Requirements:

• Wallet must not be set as the current active wallet,

• Wallet must exceed the wallet maximum age OR the wallet BTC balance must be lesser than the minimum threshold. If the latter case is true, the walletMainUtxo components must point to the recent main UTXO of the given wallet, as currently known on the Ethereum chain. If the wallet has no main UTXO, this parameter can be empty as it is ignored since the wallet balance is assumed to be zero,

• Wallet must be in Live state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.
walletMainUtxo	struct BitcoinTx.UTXO	Data of the wallet's main UTXO, as currently known on the Ethereum chain.

notifyWalletClosingPeriodElapsed

function notifyWalletClosingPeriodElapsed(struct BridgeState.Storage self, bytes20 walletPubKeyHash) internal

Notifies about the end of the closing period for the given wallet. Closes the wallet ultimately and notifies the ECDSA registry about this fact.

Requirements:

• The wallet must be in the Closing state,

• The wallet closing period must have elapsed.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.

notifyWalletFundsMoved

function notifyWalletFundsMoved(struct BridgeState.Storage self, bytes20 walletPubKeyHash, bytes32 targetWalletsHash) internal

Notifies that the wallet completed the moving funds process successfully. Checks if the funds were moved to the expected target wallets. Closes the source wallet if everything went good and reverts otherwise.

Requirements:

• The caller must make sure the moving funds transaction actually happened on Bitcoin chain and fits the protocol requirements,

• The source wallet must be in the MovingFunds state,

• The target wallets commitment must be submitted by the source wallet,

• The actual target wallets used in the moving funds transaction must be exactly the same as the target wallets commitment.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.
targetWalletsHash	bytes32	32-byte keccak256 hash over the list of 20-byte public key hashes of the target wallets actually used within the moving funds transactions.

notifyWalletMovingFundsBelowDust

function notifyWalletMovingFundsBelowDust(struct BridgeState.Storage self, bytes20 walletPubKeyHash) internal

Called when a MovingFunds wallet has a balance below the dust threshold. Begins the wallet closing.

Requirements:

• The wallet must be in the MovingFunds state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.

notifyWalletMovingFundsTimeout

function notifyWalletMovingFundsTimeout(struct BridgeState.Storage self, bytes20 walletPubKeyHash, uint32[] walletMembersIDs) internal

Called when the timeout for MovingFunds for the wallet elapsed. Slashes wallet members and terminates the wallet.

Requirements:

• The wallet must be in the MovingFunds state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.
walletMembersIDs	uint32[]	Identifiers of the wallet signing group members.

notifyWalletMovedFundsSweepTimeout

function notifyWalletMovedFundsSweepTimeout(struct BridgeState.Storage self, bytes20 walletPubKeyHash, uint32[] walletMembersIDs) internal

Called when a wallet which was asked to sweep funds moved from another wallet did not provide a sweeping proof before a timeout. Slashes and terminates the wallet who failed to provide a proof.

Requirements:

• The wallet must be in the Live, MovingFunds, or Terminated state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet which was supposed to sweep funds.
walletMembersIDs	uint32[]	Identifiers of the wallet signing group members.

notifyWalletFraudChallengeDefeatTimeout

function notifyWalletFraudChallengeDefeatTimeout(struct BridgeState.Storage self, bytes20 walletPubKeyHash, uint32[] walletMembersIDs, address challenger) internal

Called when a wallet which was challenged for a fraud did not defeat the challenge before the timeout. Slashes and terminates the wallet who failed to defeat the challenge. If the wallet is already terminated, it does nothing.

Requirements:

• The wallet must be in the Live, MovingFunds, Closing or Terminated state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet which was supposed to sweep funds.
walletMembersIDs	uint32[]	Identifiers of the wallet signing group members.
challenger	address	Address of the party which submitted the fraud challenge.

moveFunds

function moveFunds(struct BridgeState.Storage self, bytes20 walletPubKeyHash) internal

Requests a wallet to move their funds. If the wallet balance is zero, the wallet closing begins immediately. If the move funds request refers to the current active wallet, such a wallet is no longer considered active and the active wallet slot is unset allowing to trigger a new wallet creation immediately.

Requirements:

• The caller must make sure that the wallet is in the Live state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.

beginWalletClosing

function beginWalletClosing(struct BridgeState.Storage self, bytes20 walletPubKeyHash) internal

Begins the closing period of the given wallet.

Requirements:

• The caller must make sure that the wallet is in the MovingFunds state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.

finalizeWalletClosing

function finalizeWalletClosing(struct BridgeState.Storage self, bytes20 walletPubKeyHash) internal

Finalizes the closing period of the given wallet and notifies the ECDSA registry about this fact.

Requirements:

• The caller must make sure that the wallet is in the Closing state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.

terminateWallet

function terminateWallet(struct BridgeState.Storage self, bytes20 walletPubKeyHash) internal

Terminates the given wallet and notifies the ECDSA registry about this fact. If the wallet termination refers to the current active wallet, such a wallet is no longer considered active and the active wallet slot is unset allowing to trigger a new wallet creation immediately.

Requirements:

• The caller must make sure that the wallet is in the Live or MovingFunds or Closing state.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.

getWalletBtcBalance

function getWalletBtcBalance(struct BridgeState.Storage self, bytes20 walletPubKeyHash, struct BitcoinTx.UTXO walletMainUtxo) internal view returns (uint64 walletBtcBalance)

Gets BTC balance for given the wallet.

Requirements:

• walletMainUtxo components must point to the recent main UTXO of the given wallet, as currently known on the Ethereum chain. If the wallet has no main UTXO, this parameter can be empty as it is ignored.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
walletPubKeyHash	bytes20	20-byte public key hash of the wallet.
walletMainUtxo	struct BitcoinTx.UTXO	Data of the wallet's main UTXO, as currently known on the Ethereum chain.

Return Values

Name	Type	Description
walletBtcBalance	uint64	Current BTC balance for the given wallet.