Deposit

Deposit

The library handles the logic for revealing Bitcoin deposits to the Bridge.

The depositor puts together a P2SH or P2WSH address to deposit the funds. This script is unique to each depositor and looks like this:

<depositorAddress> DROP
<blindingFactor> DROP
DUP HASH160 <walletPubKeyHash> EQUAL
IF
CHECKSIG
ELSE
DUP HASH160 <refundPubkeyHash> EQUALVERIFY
<refundLocktime> CHECKLOCKTIMEVERIFY DROP
CHECKSIG
ENDIF

Since each depositor has their own Ethereum address and their own blinding factor, each depositor’s script is unique, and the hash of each depositor’s script is unique.

DepositRevealInfo

struct DepositRevealInfo {
  uint32 fundingOutputIndex;
  bytes8 blindingFactor;
  bytes20 walletPubKeyHash;
  bytes20 refundPubKeyHash;
  bytes4 refundLocktime;
  address vault;
}

DepositRequest

struct DepositRequest {
  address depositor;
  uint64 amount;
  uint32 revealedAt;
  address vault;
  uint64 treasuryFee;
  uint32 sweptAt;
}

DepositRevealed

event DepositRevealed(bytes32 fundingTxHash, uint32 fundingOutputIndex, address depositor, uint64 amount, bytes8 blindingFactor, bytes20 walletPubKeyHash, bytes20 refundPubKeyHash, bytes4 refundLocktime, address vault)

revealDeposit

function revealDeposit(struct BridgeState.Storage self, struct BitcoinTx.Info fundingTx, struct Deposit.DepositRevealInfo reveal) external

Used by the depositor to reveal information about their P2(W)SH Bitcoin deposit to the Bridge on Ethereum chain. The off-chain wallet listens for revealed deposit events and may decide to include the revealed deposit in the next executed sweep. Information about the Bitcoin deposit can be revealed before or after the Bitcoin transaction with P2(W)SH deposit is mined on the Bitcoin chain. Worth noting, the gas cost of this function scales with the number of P2(W)SH transaction inputs and outputs. The deposit may be routed to one of the trusted vaults. When a deposit is routed to a vault, vault gets notified when the deposit gets swept and it may execute the appropriate action.

Requirements:

• This function must be called by the same Ethereum address as the one used in the P2(W)SH BTC deposit transaction as a depositor,

• reveal.walletPubKeyHash must identify a Live wallet,

• reveal.vault must be 0x0 or point to a trusted vault,

• reveal.fundingOutputIndex must point to the actual P2(W)SH output of the BTC deposit transaction,

• reveal.blindingFactor must be the blinding factor used in the P2(W)SH BTC deposit transaction,

• reveal.walletPubKeyHash must be the wallet pub key hash used in the P2(W)SH BTC deposit transaction,

• reveal.refundPubKeyHash must be the refund pub key hash used in the P2(W)SH BTC deposit transaction,

• reveal.refundLocktime must be the refund locktime used in the P2(W)SH BTC deposit transaction,

• BTC deposit for the given fundingTxHash, fundingOutputIndex can be revealed only one time.

If any of these requirements is not met, the wallet must refuse to sweep the deposit and the depositor has to wait until the deposit script unlocks to receive their BTC back.

Parameters

Name	Type	Description
self	struct BridgeState.Storage
fundingTx	struct BitcoinTx.Info	Bitcoin funding transaction data, see BitcoinTx.Info.
reveal	struct Deposit.DepositRevealInfo	Deposit reveal data, see `RevealInfo struct.

validateDepositRefundLocktime

function validateDepositRefundLocktime(struct BridgeState.Storage self, bytes4 refundLocktime) internal view

Validates the deposit refund locktime. The validation passes successfully only if the deposit reveal is done respectively earlier than the moment when the deposit refund locktime is reached, i.e. the deposit become refundable. Reverts otherwise.

Requirements:

• refundLocktime as integer must be >= 500M

• refundLocktime must denote a timestamp that is at least depositRevealAheadPeriod seconds later than the moment of block.timestamp

Parameters

Name	Type	Description
self	struct BridgeState.Storage
refundLocktime	bytes4	The deposit refund locktime as 4-byte LE.