Refactor IKeep/KeepBridge

implementation/contracts/deposit/Deposit.sol

@@ -36,13 +36,11 @@ contract Deposit {
     function createNewDeposit(
         address _TBTCSystem,
         address _TBTCToken,
-        address _KeepBridge,
         uint256 _m,
         uint256 _n
     ) public payable returns (bool) {
         self.TBTCSystem = _TBTCSystem;
         self.TBTCToken = _TBTCToken;
-        self.KeepBridge = _KeepBridge;
         self.createNewDeposit(_m, _n);
         return true;
     }

implementation/contracts/deposit/DepositFunding.sol

@@ -3,8 +3,11 @@ pragma solidity ^0.5.10;
 import {SafeMath} from "bitcoin-spv/contracts/SafeMath.sol";
 import {BytesLib} from "bitcoin-spv/contracts/BytesLib.sol";
 import {BTCUtils} from "bitcoin-spv/contracts/BTCUtils.sol";
+
+import {IECDSAKeep} from "keep-tecdsa/solidity/contracts/api/IECDSAKeep.sol";
+
 import {TBTCToken} from "../system/TBTCToken.sol";
-import {IKeep} from "../interfaces/IKeep.sol";
+import {TBTCSystem} from "../system/TBTCSystem.sol";
 import {DepositUtils} from "./DepositUtils.sol";
 import {DepositLiquidation} from "./DepositLiquidation.sol";
 import {DepositStates} from "./DepositStates.sol";
@@ -39,17 +42,6 @@ library DepositFunding {
         _d.signingGroupPubkeyY = bytes32(0);
     }
 
-    /// @notice         get the signer pubkey for our keep
-    /// @dev            calls out to the keep contract, should get 64 bytes back
-    /// @return         the 64 byte pubkey
-    function getKeepPubkeyResult(DepositUtils.Deposit storage _d) public view returns (bytes memory) {
-        IKeep _keep = IKeep(_d.KeepBridge);
-        bytes memory _pubkey = _keep.getKeepPubkey(_d.keepAddress);
-        /* solium-disable-next-line */
-        require(_pubkey.length == 64, "public key not set or not 64-bytes long");
-        return _pubkey;
-    }
-
     /// @notice         The system can spin up a new deposit
     /// @dev            This should be called by an approved contract, not a developer
     /// @param _d       deposit storage pointer
@@ -63,10 +55,10 @@ library DepositFunding {
     ) public returns (bool) {
         require(_d.inStart(), "Deposit setup already requested");
 
-        IKeep _keep = IKeep(_d.KeepBridge);
-
+        // TODO: Whole value is forwarded to TBTC System, but should be partially
+        // stored as funder's bond in the deposit https://github.com/keep-network/tbtc/issues/279.
         /* solium-disable-next-line value-in-payable */
-        _d.keepAddress = _keep.requestNewKeep.value(msg.value)(_m, _n);  // kinda gross but
+        _d.keepAddress = TBTCSystem(_d.TBTCSystem).requestNewKeep.value(msg.value)(_m, _n);  // kinda gross but
         _d.signingGroupRequestedAt = block.timestamp;
 
         _d.setAwaitingSignerSetup();
@@ -150,10 +142,12 @@ library DepositFunding {
     /// @return             True if successful, otherwise revert
     function retrieveSignerPubkey(DepositUtils.Deposit storage _d) public {
         require(_d.inAwaitingSignerSetup(), "Not currently awaiting signer setup");
-        bytes memory _keepResult = getKeepPubkeyResult(_d);
 
-        _d.signingGroupPubkeyX = _keepResult.slice(0, 32).toBytes32();
-        _d.signingGroupPubkeyY = _keepResult.slice(32, 32).toBytes32();
+        bytes memory _publicKey = IECDSAKeep(_d.keepAddress).getPublicKey();
+        require(_publicKey.length == 64, "public key not set or not 64-bytes long");
+
+        _d.signingGroupPubkeyX = _publicKey.slice(0, 32).toBytes32();
+        _d.signingGroupPubkeyY = _publicKey.slice(32, 32).toBytes32();
         require(_d.signingGroupPubkeyY != bytes32(0) && _d.signingGroupPubkeyX != bytes32(0), "Keep returned bad pubkey");
         _d.fundingProofTimerStart = block.timestamp;
 

implementation/contracts/deposit/DepositLiquidation.sol

@@ -5,7 +5,7 @@ import {BTCUtils} from "bitcoin-spv/contracts/BTCUtils.sol";
 import {DepositStates} from "./DepositStates.sol";
 import {DepositUtils} from "./DepositUtils.sol";
 import {TBTCConstants} from "./TBTCConstants.sol";
-import {IKeep} from "../interfaces/IKeep.sol";
+import {IBondedECDSAKeep} from "../external/IBondedECDSAKeep.sol";
 import {OutsourceDepositLogging} from "./OutsourceDepositLogging.sol";
 import {TBTCToken} from "../system/TBTCToken.sol";
 
@@ -42,7 +42,7 @@ library DepositLiquidation {
         bytes32 _signedDigest,
         bytes memory _preimage
     ) public returns (bool _isFraud) {
-        IKeep _keep = IKeep(_d.KeepBridge);
+        IBondedECDSAKeep _keep = IBondedECDSAKeep(_d.keepAddress);
         return _keep.submitSignatureFraud(_d.keepAddress, _v, _r, _s, _signedDigest, _preimage);
     }
 

implementation/contracts/deposit/DepositRedemption.sol

@@ -6,7 +6,8 @@ import {BytesLib} from "bitcoin-spv/contracts/BytesLib.sol";
 import {ValidateSPV} from "bitcoin-spv/contracts/ValidateSPV.sol";
 import {CheckBitcoinSigs} from "bitcoin-spv/contracts/SigCheck.sol";
 import {DepositUtils} from "./DepositUtils.sol";
-import {IKeep} from "../interfaces/IKeep.sol";
+import {IBondedECDSAKeep} from "../external/IBondedECDSAKeep.sol";
+import {IECDSAKeep} from "keep-tecdsa/solidity/contracts/api/IECDSAKeep.sol";
 import {DepositStates} from "./DepositStates.sol";
 import {OutsourceDepositLogging} from "./OutsourceDepositLogging.sol";
 import {TBTCConstants} from "./TBTCConstants.sol";
@@ -33,19 +34,20 @@ library DepositRedemption {
         address _tbtcTokenAddress = _d.TBTCToken;
         TBTCToken _tbtcToken = TBTCToken(_tbtcTokenAddress);
 
-        IKeep _keep = IKeep(_d.KeepBridge);
+        IBondedECDSAKeep _keep = IBondedECDSAKeep(_d.keepAddress);
 
-        _tbtcToken.approve(_d.KeepBridge, DepositUtils.signerFee());
+        _tbtcToken.approve(_d.keepAddress, DepositUtils.signerFee());
         _keep.distributeERC20ToKeepGroup(_d.keepAddress, _tbtcTokenAddress, DepositUtils.signerFee());
     }
 
-    /// @notice         approves a digest for signing by our keep group
-    /// @dev            calls out to the keep contract
-    /// @param  _digest the digest to approve
-    /// @return         true if approved, otherwise revert
-    function approveDigest(DepositUtils.Deposit storage _d, bytes32 _digest) public returns (bool) {
-        IKeep _keep = IKeep(_d.KeepBridge);
-        return _keep.approveDigest(_d.keepAddress, _digest);
+    /// @notice Approves digest for signing by a keep
+    /// @dev Calls given keep to sign the digest. Records a current timestamp
+    /// for given digest
+    /// @param _digest Digest to approve
+    function approveDigest(DepositUtils.Deposit storage _d, bytes32 _digest) internal {
+        IECDSAKeep(_d.keepAddress).sign(_digest);
+
+        _d.approvedDigests[_digest] = block.timestamp;
     }
 
     function redemptionTBTCBurn(DepositUtils.Deposit storage _d) private {
@@ -93,7 +95,8 @@ library DepositRedemption {
         _d.initialRedemptionFee = _requestedFee;
         _d.withdrawalRequestTime = block.timestamp;
         _d.lastRequestedDigest = _sighash;
-        require(approveDigest(_d, _sighash), "Keep returned false");
+
+        approveDigest(_d, _sighash);
 
         _d.setAwaitingWithdrawalSignature();
         _d.logRedemptionRequested(
@@ -168,7 +171,8 @@ library DepositRedemption {
         // Ratchet the signature and redemption proof timeouts
         _d.withdrawalRequestTime = block.timestamp;
         _d.lastRequestedDigest = _sighash;
-        require(approveDigest(_d, _sighash), "Keep returned false");
+
+        approveDigest(_d, _sighash);
 
         // Go back to waiting for a signature
         _d.setAwaitingWithdrawalSignature();

implementation/contracts/deposit/DepositUtils.sol

@@ -7,7 +7,7 @@ import {BytesLib} from "bitcoin-spv/contracts/BytesLib.sol";
 import {TBTCConstants} from "./TBTCConstants.sol";
 import {ITBTCSystem} from "../interfaces/ITBTCSystem.sol";
 import {IERC721} from "../interfaces/IERC721.sol";
-import {IKeep} from "../interfaces/IKeep.sol";
+import {IBondedECDSAKeep} from "../external/IBondedECDSAKeep.sol";
 import {TBTCToken} from "../system/TBTCToken.sol";
 
 library DepositUtils {
@@ -24,7 +24,6 @@ library DepositUtils {
         // SET DURING CONSTRUCTION
         address TBTCSystem;
         address TBTCToken;
-        address KeepBridge;
         uint8 currentState;
 
         // SET ON FRAUD
@@ -51,6 +50,11 @@ library DepositUtils {
         bytes8 utxoSizeBytes;  // LE uint. the size of the deposit UTXO in satoshis
         uint256 fundedAt; // timestamp when funding proof was received
         bytes utxoOutpoint;  // the 36-byte outpoint of the custodied UTXO
+
+        /// @notice Map of timestamps for transaction digests approved for signing
+        /// @dev Holds a timestamp from the moment when the transaction digest
+        /// was approved for signing
+        mapping (bytes32 => uint256) approvedDigests;
     }
 
     /// @notice         Gets the current block difficulty
@@ -363,7 +367,7 @@ library DepositUtils {
     /// @dev        Calls the keep contract to do so
     /// @return     The amount of bonded ETH in wei
     function fetchBondAmount(Deposit storage _d) public view returns (uint256) {
-        IKeep _keep = IKeep(_d.KeepBridge);
+        IBondedECDSAKeep _keep = IBondedECDSAKeep(_d.keepAddress);
         return _keep.checkBondAmount(_d.keepAddress);
     }
 
@@ -374,13 +378,13 @@ library DepositUtils {
         return abi.encodePacked(_b).reverseEndianness().bytesToUint();
     }
 
-    /// @notice         determines whether a digest has been approved for our keep group
-    /// @dev            calls out to the keep contract, storing a 256bit int costs the same as a bool
-    /// @param  _digest the digest to check approval time for
-    /// @return         the time it was approved. 0 if unapproved
+    /// @notice Gets timestamp of digest approval for signing
+    /// @dev Identifies entry in the recorded approvals by keep ID and digest pair
+    /// @param _digest Digest to check approval for
+    /// @return Timestamp from the moment of recording the digest for signing.
+    /// Returns 0 if the digest was not approved for signing
     function wasDigestApprovedForSigning(Deposit storage _d, bytes32 _digest) public view returns (uint256) {
-        IKeep _keep = IKeep(_d.KeepBridge);
-        return _keep.wasDigestApprovedForSigning(_d.keepAddress, _digest);
+        return _d.approvedDigests[_digest];
     }
 
     /// @notice         Looks up the deposit beneficiary by calling the tBTC system
@@ -406,7 +410,7 @@ library DepositUtils {
     /// @return     the amount of ether seized
     function seizeSignerBonds(Deposit storage _d) public returns (uint256) {
         uint256 _preCallBalance = address(this).balance;
-        IKeep _keep = IKeep(_d.KeepBridge);
+        IBondedECDSAKeep _keep = IBondedECDSAKeep(_d.keepAddress);
         _keep.seizeSignerBonds(_d.keepAddress);
         uint256 _postCallBalance = address(this).balance;
         require(_postCallBalance > _preCallBalance, "No funds received, unexpected");
@@ -428,7 +432,7 @@ library DepositUtils {
     /// @return             true if successful, otherwise revert
     function pushFundsToKeepGroup(Deposit storage _d, uint256 _ethValue) public returns (bool) {
         require(address(this).balance >= _ethValue, "Not enough funds to send");
-        IKeep _keep = IKeep(_d.KeepBridge);
+        IBondedECDSAKeep _keep = IBondedECDSAKeep(_d.keepAddress);
         return _keep.distributeEthToKeepGroup.value(_ethValue)(_d.keepAddress);
     }
 }

implementation/contracts/interfaces/IKeep.sol → implementation/contracts/external/IBondedECDSAKeep.sol

@@ -1,33 +1,8 @@
 pragma solidity ^0.5.10;
 
-/**
- * @title Keep interface
- */
-
-interface IKeep {
-
-    // request a new m-of-n group
-    // should return a unique keep contract address
-    function requestNewKeep(uint256 _m, uint256 _n) external payable returns (address _keepAddress);
-
-    // get the result of a keep formation
-    // should return a 64 byte packed pubkey (x and y)
-    // error if not ready yet
-    function getKeepPubkey(address _keepAddress) external view returns (bytes memory);
-
-    /// @notice Approves digest for signing.
-    /// @param _keepAddress Keep address
-    /// @param _digest Digest to sign
-    /// @return True if successful.
-    function approveDigest(address _keepAddress, bytes32 _digest) external returns (bool _success);
-
-    /// @notice Gets timestamp of digest approval for signing.
-    /// @param _keepAddress Keep address
-    /// @param _digest Digest to sign
-    /// @return Timestamp from the moment of recording the digest for signing.
-    /// Returns 0 if the digest was not recorded for signing for the given keep.
-    function wasDigestApprovedForSigning(address _keepAddress, bytes32 _digest) external view returns (uint256);
-
+// TODO: This is a contract holding functions which are required to be implemented
+// on keep side and added to IBondedECDSAKeep interface.
+interface IBondedECDSAKeep {
     // Expected behavior:
     // Error if not fraud
     // Return true if fraud
@@ -47,7 +22,7 @@ interface IKeep {
 
     // Allow sending tokens to a keep group
     // Useful for sending signers their TBTC
-    // The Keep contract should call transferFrom on the token contrcact
+    // The Keep contract should call transferFrom on the token contract
     function distributeERC20ToKeepGroup(address _keepAddress, address _asset, uint256 _value) external returns (bool);
 
     // returns the amount of the keep's ETH bond in wei