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Merge pull request #399 from deepesh-kn/gh_335
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Votes should be hashed according to EIP-712 #335
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@schemar
schemar authored Oct 23, 2018
2 parents dc56035 + 7774af9 commit 51d6eb8
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199 changes: 148 additions & 51 deletions contracts/core/PollingPlace.sol
View file
Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,57 @@ contract PollingPlace is PollingPlaceInterface {
uint256 endHeight;
}

/** Vote message */
struct VoteMessage {

/**
* A unique identifier that identifies what chain this vote is about.
* To generate the vote hash coreIdentifier is needed. As the votes are
* for both origin and auxiliary chain, the core identifier information
* is stored in this struct.
*/
bytes20 coreIdentifier;

/**
* The hash of the transition object of the meta-block that would
* result from the source block being finalised and proposed to origin.
*/
bytes32 transitionHash;

/** The hash of the source block. */
bytes32 source;

/** The hash of the target block. */
bytes32 target;

/** The height of the source block. */
uint256 sourceHeight;

/** The height of the target block. */
uint256 targetHeight;
}

/** Vote object */
struct Vote {

/** Vote message. */
VoteMessage voteMessage;

/** v component of signature */
uint8 v;

/** r component of signature */
bytes32 r;

/** s component of signature */
bytes32 s;
}

/** To hash vote message according to EIP-712, a type hash is required. */
bytes32 constant VOTE_MESSAGE_TYPEHASH = keccak256(
"VoteMessage(bytes20 coreIdentifier,bytes32 transitionHash,bytes32 source,bytes32 target,uint256 sourceHeight,uint256 targetHeight)"
);

/* Public Variables */

/**
Expand Down Expand Up @@ -300,28 +351,33 @@ contract PollingPlace is PollingPlaceInterface {
BlockStoreInterface blockStore = blockStores[_coreIdentifier];
require(
address(blockStore) != address(0),
"The providede core identifier must be known to the PollingPlace."
"The provided core identifier must be known to the PollingPlace."
);

require(
blockStore.isVoteValid(_transitionHash, _source, _target),
"The provided vote is not valid according to the block store."
);

bytes32 voteHash = hashVote(
Vote memory voteObject = getVoteObject(
_coreIdentifier,
_transitionHash,
_source,
_target,
_sourceHeight,
_targetHeight
);
Validator storage validator = getValidatorFromVote(
voteHash,
_targetHeight,
_v,
_r,
_s
);

bytes32 voteHash = hashVote(voteObject.voteMessage);

Validator storage validator = getValidatorFromVote(
voteObject,
voteHash
);

require(validator.auxiliaryAddress != address(0), "Vote by unknown validator.");

require(
Expand All @@ -330,10 +386,8 @@ contract PollingPlace is PollingPlaceInterface {
);

storeVote(
voteObject,
voteHash,
_source,
_target,
_targetHeight,
validator,
blockStore
);
Expand Down Expand Up @@ -426,27 +480,28 @@ contract PollingPlace is PollingPlaceInterface {
* store.
*
* @dev All requirement checks must have been made before calling this
* method.
* method. As this function is private, we can trust that vote hash
* will be correct. In case if this function changes to external or
* public then we should calculate the vote hash from the vote object in this
* function.
*
*
* @param _voteHash The hash of the vote object. The hash is used to
* identify the vote.
* @param _source The hash of the source checkpoint of the vote.
* @param _target The hash of the target checkpoint of the vote.
* @param _targetHeight The height of the target block of the vote.
* @param _voteObject Vote object.
* @param _voteHash Hash of the VoteMessage.
* @param _validator The validator that signed the vote.
* @param _blockStore The block store that this vote is about.
*/
function storeVote(
Vote memory _voteObject,
bytes32 _voteHash,
bytes32 _source,
bytes32 _target,
uint256 _targetHeight,
Validator storage _validator,
BlockStoreInterface _blockStore
)
private
{
validatorTargetHeights[_validator.auxiliaryAddress] = _targetHeight;
VoteMessage memory voteMessage = _voteObject.voteMessage;

validatorTargetHeights[_validator.auxiliaryAddress] = voteMessage.targetHeight;
votesWeights[_voteHash] += validatorWeight(_validator, currentMetaBlockHeight);

/*
Expand All @@ -456,7 +511,7 @@ contract PollingPlace is PollingPlaceInterface {
uint256 required = requiredWeight(currentMetaBlockHeight);

if (votesWeights[_voteHash] >= required) {
_blockStore.justify(_source, _target);
_blockStore.justify(voteMessage.source, voteMessage.target);
}
}

Expand All @@ -482,25 +537,28 @@ contract PollingPlace is PollingPlaceInterface {
* @notice Uses the signature of a vote to recover the public address of
* the signer.
*
* @param _voteHash The hashed vote. It is the message that was signed.
* @param _v V of the signature.
* @param _r R of teh signature.
* @param _s S of the signature.
* @dev As this function is private, we can trust that vote hash will be
* correct. In case if this function changes to external or public
* then we should calculate the vote hash from the vote object in this
* function.
*
* @param _voteObject Vote object.
* @param _voteHash Hash of vote message.
*
* @return The `Validator` that signed the given message with the given
* signature.
*/
function getValidatorFromVote(
bytes32 _voteHash,
uint8 _v,
bytes32 _r,
bytes32 _s
)
function getValidatorFromVote(Vote memory _voteObject, bytes32 _voteHash)
private
view
returns (Validator storage validator_)
{
address signer = ecrecover(_voteHash, _v, _r, _s);
address signer = ecrecover(
_voteHash,
_voteObject.v,
_voteObject.r,
_voteObject.s
);
validator_ = validators[signer];
}

Expand Down Expand Up @@ -564,35 +622,24 @@ contract PollingPlace is PollingPlaceInterface {
* @notice Creates the hash of o vote object. This is the same hash that
* the validator has signed.
*
* @param _coreIdentifier Core identifier of the vote object.
* @param _transitionHash Transition hash of the vote object.
* @param _source Source block hash of the vote object.
* @param _target Target block hash of the vote object.
* @param _sourceHeight Source height of the vote object.
* @param _targetHeight Target height of the vote object.
* @param _voteMessage Vote message object.
*
* @return The hash of the given vote.
*/
function hashVote(
bytes20 _coreIdentifier,
bytes32 _transitionHash,
bytes32 _source,
bytes32 _target,
uint256 _sourceHeight,
uint256 _targetHeight
)
function hashVote(VoteMessage memory _voteMessage)
private
pure
returns (bytes32 hashed_)
{
hashed_ = keccak256(
abi.encodePacked(
_coreIdentifier,
_transitionHash,
_source,
_target,
_sourceHeight,
_targetHeight
VOTE_MESSAGE_TYPEHASH,
_voteMessage.coreIdentifier,
_voteMessage.transitionHash,
_voteMessage.source,
_voteMessage.target,
_voteMessage.sourceHeight,
_voteMessage.targetHeight
)
);

Expand All @@ -605,4 +652,54 @@ contract PollingPlace is PollingPlaceInterface {
)
);
}

/**
* @notice Creates a vote object
*
* @param _coreIdentifier A unique identifier that identifies what chain
* this vote is about.
* @param _transitionHash The hash of the transition object of the
* meta-block that would result from the source
* block being finalised and proposed to origin.
* @param _source The hash of the source block.
* @param _target The hash of the target block.
* @param _sourceHeight The height of the source block.
* @param _targetHeight The height of the target block.
* @param _v V of the signature.
* @param _r R of the signature.
* @param _s S of the signature.
*
* @return vote object
*/
function getVoteObject(
bytes20 _coreIdentifier,
bytes32 _transitionHash,
bytes32 _source,
bytes32 _target,
uint256 _sourceHeight,
uint256 _targetHeight,
uint8 _v,
bytes32 _r,
bytes32 _s
)
private
pure
returns (Vote memory voteObject_)
{
VoteMessage memory voteMessage = VoteMessage(
_coreIdentifier,
_transitionHash,
_source,
_target,
_sourceHeight,
_targetHeight
);

voteObject_ = Vote(
voteMessage,
_v,
_r,
_s
);
}
}
6 changes: 6 additions & 0 deletions test/core/PollingPlace.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,10 @@ const ValidatorIndexEnded = 2;
const ValidatorIndexStartHeight = 3;
const ValidatorIndexEndHeight = 4;

const VOTE_MESSAGE_TYPEHASH = web3.utils.sha3(
"VoteMessage(bytes20 coreIdentifier,bytes32 transitionHash,bytes32 source,bytes32 target,uint256 sourceHeight,uint256 targetHeight)"
);

contract('PollingPlace', async (accounts) => {
/*
* Make the first address the default meta-block gate to be able to
Expand Down Expand Up @@ -1071,7 +1075,9 @@ contract('PollingPlace', async (accounts) => {
* @returns {object} The signature of the vote (r, s, and v).
*/
async function signVote(address, vote) {

let voteDigest = web3.utils.soliditySha3(
{type: 'bytes32', value: VOTE_MESSAGE_TYPEHASH},
{type: 'bytes20', value: web3.utils.toChecksumAddress(vote.coreIdentifier)},
{type: 'bytes32', value: vote.transitionHash},
{type: 'bytes32', value: vote.source},
Expand Down

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