From 245a4626eebe24db70debe57caa1ebdc9b6c8a58 Mon Sep 17 00:00:00 2001
From: Michele Balistreri <michele@bitgamma.com>
Date: Tue, 29 Sep 2020 08:47:58 +0200
Subject: [PATCH] use ECDSA utils from OpenZeppelin

---
 status-pay/contracts/EVMUtils.sol        | 22 ----------------------
 status-pay/contracts/StatusPay.sol       |  6 ++++--
 status-pay/contracts/StatusPayBucket.sol |  4 +++-
 3 files changed, 7 insertions(+), 25 deletions(-)

diff --git a/status-pay/contracts/EVMUtils.sol b/status-pay/contracts/EVMUtils.sol
index 854638b..596d844 100644
--- a/status-pay/contracts/EVMUtils.sol
+++ b/status-pay/contracts/EVMUtils.sol
@@ -12,28 +12,6 @@ library EVMUtils {
     ));
   }
 
-  function recoverSigner(bytes32 _digest, bytes memory _sig) internal pure returns (address) {
-    require(_sig.length == 65, "bad signature length");
-
-    bytes32 r;
-    bytes32 s;
-    uint8 v;
-
-	  // solium-disable-next-line security/no-inline-assembly
-    assembly {
-      r := mload(add(_sig, 32))
-      s := mload(add(_sig, 64))
-      v := byte(0, mload(add(_sig, 96)))
-    }
-
-    if (v < 27) {
-      v += 27;
-    }
-
-    require(v == 27 || v == 28, "signature version doesn't match");
-    return ecrecover(_digest, v, r, s);
-  }
-
   function getChainID() internal pure returns (uint256) {
     uint256 id;
     assembly {
diff --git a/status-pay/contracts/StatusPay.sol b/status-pay/contracts/StatusPay.sol
index 339a1a1..45ec155 100644
--- a/status-pay/contracts/StatusPay.sol
+++ b/status-pay/contracts/StatusPay.sol
@@ -3,6 +3,8 @@ pragma solidity >=0.5.0 <0.7.0;
 pragma experimental ABIEncoderV2;
 
 import "@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/IERC20.sol";
+import "@openzeppelin/contracts-ethereum-package/contracts/cryptography/ECDSA.sol";
+
 import "./IBlockRelay.sol";
 import "./BlockConsumer.sol";
 import "./EVMUtils.sol";
@@ -154,7 +156,7 @@ contract StatusPay is BlockConsumer {
 
   function unlockAccount(Unlock memory _unlock, bytes memory _signature) public {
     require(owners[msg.sender] == address(0), "this owner already has an account");
-    address signer = EVMUtils.recoverSigner(EVMUtils.eip712Hash(DOMAIN_SEPARATOR, hashUnlock(_unlock)), _signature);
+    address signer = ECDSA.recover(EVMUtils.eip712Hash(DOMAIN_SEPARATOR, hashUnlock(_unlock)), _signature);
     address accountAddress = keycards[signer];
 
     validateAnchorBlock(_unlock.blockNumber, _unlock.blockHash, maxTxDelayInBlocks);
@@ -171,7 +173,7 @@ contract StatusPay is BlockConsumer {
   }
 
   function requestPayment(Payment memory _payment, bytes memory _signature) public {
-    address signer = EVMUtils.recoverSigner(EVMUtils.eip712Hash(DOMAIN_SEPARATOR, hashPayment(_payment)), _signature);
+    address signer = ECDSA.recover(EVMUtils.eip712Hash(DOMAIN_SEPARATOR, hashPayment(_payment)), _signature);
     Account storage payer = accounts[keycards[signer]];
 
     // allow direct payment without Keycard from owner
diff --git a/status-pay/contracts/StatusPayBucket.sol b/status-pay/contracts/StatusPayBucket.sol
index 5036392..a5816b2 100644
--- a/status-pay/contracts/StatusPayBucket.sol
+++ b/status-pay/contracts/StatusPayBucket.sol
@@ -3,6 +3,8 @@ pragma solidity >=0.5.0 <0.7.0;
 pragma experimental ABIEncoderV2;
 
 import "@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/IERC20.sol";
+import "@openzeppelin/contracts-ethereum-package/contracts/cryptography/ECDSA.sol";
+
 import "./StatusPay.sol";
 import "./IBlockRelay.sol";
 import "./BlockConsumer.sol";
@@ -76,7 +78,7 @@ contract StatusPayBucket is BlockConsumer {
     require(blockTimestamp() < expirationTime, "expired redeemable");
     require(blockTimestamp() > startTime, "reedeming not yet started");
 
-    address recipient = EVMUtils.recoverSigner(EVMUtils.eip712Hash(DOMAIN_SEPARATOR, hashRedeem(_redeem)), _sig);
+    address recipient = ECDSA.recover(EVMUtils.eip712Hash(DOMAIN_SEPARATOR, hashRedeem(_redeem)), _sig);
 
     Redeemable storage redeemable = redeemables[recipient];
     require(redeemable.recipient == recipient, "not found");