# Information about validators validators: public({ # Amount of wei the validator holds deposit: wei_value, # The dynasty the validator is joining dynasty_start: num, # The dynasty the validator is leaving dynasty_end: num, # The timestamp at which the validator can withdraw withdrawal_epoch: num, # The address which the validator's signatures must verify to (to be later replaced with validation code) addr: address, # Addess to withdraw to withdrawal_addr: address, # The max epoch at which the validator prepared max_prepared: num, # The max epoch at which the validator committed max_committed: num }[num]) # The current dynasty (validator set changes between dynasties) dynasty: public(num) # Amount of wei added to the total deposits in the next dynasty next_dynasty_wei_delta: wei_value # Amount of wei added to the total deposits in the dynasty after that second_next_dynasty_wei_delta: wei_value # Total deposits during this dynasty total_deposits: public(wei_value[num]) # Mapping of dynasty to start epoch of that dynasty dynasty_start_epoch: public(num[num]) # Information for use in processing cryptoeconomic commitments consensus_messages: public({ # How many prepares are there for this hash (hash of message hash + view source) from the current dynasty prepares: wei_value[bytes32], # From the previous dynasty prev_dyn_prepares: wei_value[bytes32], # Is a prepare referencing the given ancestry hash justified? ancestry_hash_justified: bool[bytes32], # Is a commit on the given hash justified? hash_justified: bool[bytes32], # How many commits are there for this hash commits: wei_value[bytes32], # And from the previous dynasty prev_dyn_commits: wei_value[bytes32], # Was the block committed? committed: bool, # Value used to calculate the per-epoch fee that validators should be charged deposit_scale_factor: decimal }[num]) # index: epoch # ancestry[x][y] = k > 0: x is a kth generation ancestor of y ancestry: public(num[bytes32][bytes32]) # Number of validators nextValidatorIndex: public(num) # Time between blocks block_time: timedelta # Length of an epoch in blocks epoch_length: num # Withdrawal delay withdrawal_delay: timedelta # Delay after which a message can be slashed due to absence of justification insufficiency_slash_delay: timedelta # Current epoch current_epoch: public(num) # Can withdraw destroyed deposits owner: address # Total deposits destroyed total_destroyed: wei_value # Sighash calculator library address sighasher: address # Reward for preparing or committing, as fraction of deposit size reward_factor: public(decimal) # Desired total ether given out assuming 1M ETH deposited reward_at_1m_eth: decimal # Have I already been initialized? initialized: bool # Log topic for prepare prepare_log_topic: bytes32 # Log topic for commit commit_log_topic: bytes32 def initiate(): assert not self.initialized self.initialized = True # Set Casper parameters self.block_time = 14 self.epoch_length = 100 # Only ~11.5 days, for testing purposes self.withdrawal_delay = 1000000 # Only ~1 day, for testing purposes self.insufficiency_slash_delay = 86400 # Temporary backdoor for testing purposes (to allow recovering destroyed deposits) self.owner = 0x1db3439a222c519ab44bb1144fc28167b4fa6ee6 # Add an initial validator self.validators[0] = { deposit: as_wei_value(3, ether), dynasty_start: 0, dynasty_end: 1000000000000000000000000000000, withdrawal_epoch: 1000000000000000000000000000000, addr: 0x1db3439a222c519ab44bb1144fc28167b4fa6ee6, withdrawal_addr: 0x1db3439a222c519ab44bb1144fc28167b4fa6ee6, max_prepared: 0, max_committed: 0 } self.nextValidatorIndex = 1 # Initialize the epoch counter self.current_epoch = block.number / self.epoch_length # Set the sighash calculator address self.sighasher = 0x476c2cA9a7f3B16FeCa86512276271FAf63B6a24 # Set an initial root of the epoch hash chain self.consensus_messages[0].ancestry_hash_justified[0x0000000000000000000000000000000000000000000000000000000000000000] = True # Set initial total deposit counter self.total_deposits[0] = as_wei_value(3, ether) # Set deposit scale factor self.consensus_messages[0].deposit_scale_factor = 1000000000000000000.0 # Total ETH given out assuming 1m ETH deposits self.reward_at_1m_eth = 12.5 # Log topics for prepare and commit self.prepare_log_topic = sha3("prepare()") self.commit_log_topic = sha3("commit()") # Called at the start of any epoch def initialize_epoch(epoch: num): # Check that the epoch actually has started computed_current_epoch = block.number / self.epoch_length assert epoch <= computed_current_epoch and epoch == self.current_epoch + 1 # Set the epoch number self.current_epoch = epoch # Increment the dynasty if self.consensus_messages[epoch - 1].committed: self.dynasty += 1 self.total_deposits[self.dynasty] = self.total_deposits[self.dynasty - 1] + self.next_dynasty_wei_delta self.next_dynasty_wei_delta = self.second_next_dynasty_wei_delta self.second_next_dynasty_wei_delta = 0 self.dynasty_start_epoch[self.dynasty] = epoch # Compute square root factor ether_deposited_as_number = self.total_deposits[self.dynasty] / as_wei_value(1, ether) sqrt = ether_deposited_as_number / 2.0 for i in range(20): sqrt = (sqrt + (ether_deposited_as_number / sqrt)) / 2 # Reward factor is the reward given for preparing or committing as a # fraction of that validator's deposit size base_coeff = 1.0 / sqrt * (self.reward_at_1m_eth / 1000) # Rules: # * You are penalized 2x per epoch # * If you prepare, you get 1.5x, and if you commit you get another 1.5x # Hence, assuming 100% performance, your reward per epoch is x self.reward_factor = 1.5 * base_coeff self.consensus_messages[epoch].deposit_scale_factor = self.consensus_messages[epoch - 1].deposit_scale_factor * (1 - 2 * base_coeff) # Send a deposit to join the validator set def deposit(validation_addr: address, withdrawal_addr: address): assert self.current_epoch == block.number / self.epoch_length self.validators[self.nextValidatorIndex] = { deposit: msg.value, dynasty_start: self.dynasty + 2, dynasty_end: 1000000000000000000000000000000, withdrawal_epoch: 1000000000000000000000000000000, addr: validation_addr, withdrawal_addr: withdrawal_addr, max_prepared: 0, max_committed: 0, } self.nextValidatorIndex += 1 self.second_next_dynasty_wei_delta += msg.value # Log in or log out from the validator set. A logged out validator can log # back in later, if they do not log in for an entire withdrawal period, # they can get their money out def flick_status(validator_index: num, logout_msg: bytes <= 1024): assert self.current_epoch == block.number / self.epoch_length # Get hash for signature, and implicitly assert that it is an RLP list # consisting solely of RLP elements sighash = extract32(raw_call(self.sighasher, logout_msg, gas=200000, outsize=32), 0) # Extract parameters values = RLPList(logout_msg, [num, bool, bytes]) epoch = values[0] login_flag = values[1] sig = values[2] assert self.current_epoch == epoch # Signature check assert len(sig) == 96 assert ecrecover(sighash, as_num256(extract32(sig, 0)), as_num256(extract32(sig, 32)), as_num256(extract32(sig, 64))) == self.validators[validator_index].addr # Logging in if login_flag: # Check that we are logged out assert self.validators[validator_index].dynasty_end < self.dynasty # Apply the per-epoch deposit penalty prev_login_epoch = self.dynasty_start_epoch[self.validators[validator_index].dynasty_start] prev_logout_epoch = self.dynasty_start_epoch[self.validators[validator_index].dynasty_end + 1] self.validators[validator_index].deposit = \ floor(self.validators[validator_index].deposit * (self.consensus_messages[prev_logout_epoch].deposit_scale_factor / self.consensus_messages[prev_login_epoch].deposit_scale_factor)) # Log back in self.validators[validator_index].dynasty_start = self.dynasty + 2 self.validators[validator_index].dynasty_end = 1000000000000000000000000000000 self.second_next_dynasty_wei_delta += self.validators[validator_index].deposit # Logging out else: # Check that we haven't already withdrawn assert self.validators[validator_index].dynasty_end >= self.dynasty + 2 # Set the end dynasty self.validators[validator_index].dynasty_end = self.dynasty + 2 self.second_next_dynasty_wei_delta -= self.validators[validator_index].deposit # Set the withdrawal date self.validators[validator_index].withdrawal_epoch = self.current_epoch + self.withdrawal_delay / self.block_time / self.epoch_length # Withdraw deposited ether def withdraw(validator_index: num): # Check that we can withdraw assert self.current_epoch >= self.validators[validator_index].withdrawal_epoch # Apply the per-epoch deposit penalty prev_login_epoch = self.dynasty_start_epoch[self.validators[validator_index].dynasty_start] prev_logout_epoch = self.dynasty_start_epoch[self.validators[validator_index].dynasty_end + 1] self.validators[validator_index].deposit = \ floor(self.validators[validator_index].deposit * (self.consensus_messages[prev_logout_epoch].deposit_scale_factor / self.consensus_messages[prev_login_epoch].deposit_scale_factor)) # Withdraw send(self.validators[validator_index].withdrawal_addr, self.validators[validator_index].deposit) self.validators[validator_index] = { deposit: 0, dynasty_start: 0, dynasty_end: 0, withdrawal_epoch: 0, addr: None, withdrawal_addr: None, max_prepared: 0, max_committed: 0, } # Process a prepare message def prepare(validator_index: num, prepare_msg: bytes <= 1024): # Get hash for signature, and implicitly assert that it is an RLP list # consisting solely of RLP elements sighash = extract32(raw_call(self.sighasher, prepare_msg, gas=200000, outsize=32), 0) # Extract parameters values = RLPList(prepare_msg, [num, bytes32, bytes32, num, bytes32, bytes]) epoch = values[0] hash = values[1] ancestry_hash = values[2] source_epoch = values[3] source_ancestry_hash = values[4] sig = values[5] # For now, the sig is a simple ECDSA sig # Check the signature assert len(sig) == 96 assert ecrecover(sighash, extract32(sig, 0, type=num256), extract32(sig, 32, type=num256), extract32(sig, 64, type=num256)) == self.validators[validator_index].addr # Check that we are in the right epoch assert self.current_epoch == block.number / self.epoch_length assert self.current_epoch == epoch # Check that we are at least (epoch length / 4) blocks into the epoch # assert block.number % self.epoch_length >= self.epoch_length / 4 # Check that this validator was active in either the previous dynasty or the current one ds = self.validators[validator_index].dynasty_start de = self.validators[validator_index].dynasty_end dc = self.dynasty in_current_dynasty = (ds <= dc) and (dc < de) in_prev_dynasty = (ds <= (dc - 1)) and ((dc - 1) < de) assert in_current_dynasty or in_prev_dynasty # Check that the prepare is on top of a justified prepare assert self.consensus_messages[source_epoch].ancestry_hash_justified[source_ancestry_hash] # Check that we have not yet prepared for this epoch #assert self.validators[validator_index].max_prepared == epoch - 1 # Pay the reward if the blockhash is correct if True: #if blockhash(epoch * self.epoch_length) == hash: reward = floor(self.validators[validator_index].deposit * self.reward_factor) self.validators[validator_index].deposit += reward self.total_deposits[self.dynasty] += reward # Can't prepare for this epoch again self.validators[validator_index].max_prepared = epoch # Record that this prepare took place new_ancestry_hash = sha3(concat(hash, ancestry_hash)) if in_current_dynasty: self.consensus_messages[epoch].prepares[sighash] += self.validators[validator_index].deposit if in_prev_dynasty: self.consensus_messages[epoch].prev_dyn_prepares[sighash] += self.validators[validator_index].deposit # If enough prepares with the same epoch_source and hash are made, # then the hash value is justified for commitment if (self.consensus_messages[epoch].prepares[sighash] >= self.total_deposits[self.dynasty] * 2 / 3 and \ self.consensus_messages[epoch].prev_dyn_prepares[sighash] >= self.total_deposits[self.dynasty - 1] * 2 / 3) and \ not self.consensus_messages[epoch].ancestry_hash_justified[new_ancestry_hash]: self.consensus_messages[epoch].ancestry_hash_justified[new_ancestry_hash] = True self.consensus_messages[epoch].hash_justified[hash] = True # Add a parent-child relation between ancestry hashes to the ancestry table self.ancestry[ancestry_hash][new_ancestry_hash] = 1 raw_log([self.prepare_log_topic], prepare_msg) # Process a commit message def commit(validator_index: num, commit_msg: bytes <= 1024): sighash = extract32(raw_call(self.sighasher, commit_msg, gas=200000, outsize=32), 0) # Extract parameters values = RLPList(commit_msg, [num, bytes32, bytes]) epoch = values[0] hash = values[1] sig = values[2] # Check the signature assert len(sig) == 96 assert ecrecover(sighash, extract32(sig, 0, type=num256), extract32(sig, 32, type=num256), extract32(sig, 64, type=num256)) == self.validators[validator_index].addr # Check that we are in the right epoch assert self.current_epoch == block.number / self.epoch_length assert self.current_epoch == epoch # Check that we are at least (epoch length / 2) blocks into the epoch # assert block.number % self.epoch_length >= self.epoch_length / 2 # Check that the commit is justified assert self.consensus_messages[epoch].hash_justified[hash] # Check that this validator was active in either the previous dynasty or the current one ds = self.validators[validator_index].dynasty_start de = self.validators[validator_index].dynasty_end dc = self.dynasty in_current_dynasty = (ds <= dc) and (dc < de) in_prev_dynasty = (ds <= (dc - 1)) and ((dc - 1) < de) assert in_current_dynasty or in_prev_dynasty # Check that we have not yet committed for this epoch #assert self.validators[validator_index].max_committed == epoch - 1 # Pay the reward if the blockhash is correct if True: #if blockhash(epoch * self.epoch_length) == hash: reward = floor(self.validators[validator_index].deposit * self.reward_factor) self.validators[validator_index].deposit += reward self.total_deposits[self.dynasty] += reward # Can't commit for this epoch again self.validators[validator_index].max_committed = epoch # Record that this commit took place if in_current_dynasty: self.consensus_messages[epoch].commits[hash] += self.validators[validator_index].deposit if in_prev_dynasty: self.consensus_messages[epoch].prev_dyn_commits[hash] += self.validators[validator_index].deposit # Record if sufficient commits have been made for the block to be finalized if (self.consensus_messages[epoch].commits[hash] >= self.total_deposits[self.dynasty] * 2 / 3 and \ self.consensus_messages[epoch].prev_dyn_commits[hash] >= self.total_deposits[self.dynasty - 1] * 2 / 3) and \ not self.consensus_messages[epoch].committed: self.consensus_messages[epoch].committed = True raw_log([self.commit_log_topic], commit_msg) # Cannot make two prepares in the same epoch def double_prepare_slash(validator_index: num, prepare1: bytes <= 1000, prepare2: bytes <= 1000): # Get hash for signature, and implicitly assert that it is an RLP list # consisting solely of RLP elements sighash1 = extract32(raw_call(self.sighasher, prepare1, gas=200000, outsize=32), 0) sighash2 = extract32(raw_call(self.sighasher, prepare2, gas=200000, outsize=32), 0) # Extract parameters values1 = RLPList(prepare1, [num, bytes32, bytes32, num, bytes32, bytes]) values2 = RLPList(prepare2, [num, bytes32, bytes32, num, bytes32, bytes]) epoch1 = values1[0] sig1 = values1[5] epoch2 = values2[0] sig2 = values2[5] # Check the signatures assert ecrecover(sighash1, as_num256(extract32(sig1, 0)), as_num256(extract32(sig1, 32)), as_num256(extract32(sig1, 64))) == self.validators[validator_index].addr assert ecrecover(sighash2, as_num256(extract32(sig2, 0)), as_num256(extract32(sig2, 32)), as_num256(extract32(sig2, 64))) == self.validators[validator_index].addr # Check that they're from the same epoch assert epoch1 == epoch2 # Check that they're not the same message assert sighash1 != sighash2 # Delete the offending validator, and give a 4% "finder's fee" validator_deposit = self.validators[validator_index].deposit send(msg.sender, validator_deposit / 25) self.total_destroyed += validator_deposit * 24 / 25 self.total_deposits[self.dynasty] -= (validator_deposit - validator_deposit / 25) self.validators[validator_index] = { deposit: 0, dynasty_start: 0, dynasty_end: 0, withdrawal_epoch: 0, addr: None, withdrawal_addr: None, max_prepared: 0, max_committed: 0, } def prepare_commit_inconsistency_slash(validator_index: num, prepare_msg: bytes <= 1024, commit_msg: bytes <= 1024): # Get hash for signature, and implicitly assert that it is an RLP list # consisting solely of RLP elements sighash1 = extract32(raw_call(self.sighasher, prepare_msg, gas=200000, outsize=32), 0) sighash2 = extract32(raw_call(self.sighasher, commit_msg, gas=200000, outsize=32), 0) # Extract parameters values1 = RLPList(prepare_msg, [num, bytes32, bytes32, num, bytes32, bytes]) values2 = RLPList(commit_msg, [num, bytes32, bytes]) prepare_epoch = values1[0] prepare_source_epoch = values1[3] sig1 = values1[5] commit_epoch = values2[0] sig2 = values2[2] # Check the signatures assert ecrecover(sighash1, as_num256(extract32(sig1, 0)), as_num256(extract32(sig1, 32)), as_num256(extract32(sig1, 64))) == self.validators[validator_index].addr assert ecrecover(sighash2, as_num256(extract32(sig2, 0)), as_num256(extract32(sig2, 32)), as_num256(extract32(sig2, 64))) == self.validators[validator_index].addr # Check that they're not the same message assert sighash1 != sighash2 # Check that the prepare refers to something older than the commit assert prepare_source_epoch < commit_epoch # Check that the prepare is newer than the commit assert commit_epoch < prepare_epoch # Delete the offending validator, and give a 4% "finder's fee" validator_deposit = self.validators[validator_index].deposit send(msg.sender, validator_deposit / 25) self.total_destroyed += validator_deposit * 24 / 25 self.total_deposits[self.dynasty] -= validator_deposit self.validators[validator_index] = { deposit: 0, dynasty_start: 0, dynasty_end: 0, withdrawal_epoch: 0, addr: None, withdrawal_addr: None, max_prepared: 0, max_committed: 0, } def commit_non_justification_slash(validator_index: num, commit_msg: bytes <= 1024): sighash = extract32(raw_call(self.sighasher, commit_msg, gas=200000, outsize=32), 0) # Extract parameters values = RLPList(commit_msg, [num, bytes32, bytes]) epoch = values[0] hash = values[1] sig = values[2] # Check the signature assert len(sig) == 96 assert ecrecover(sighash, extract32(sig, 0, type=num256), extract32(sig, 32, type=num256), extract32(sig, 64, type=num256)) == self.validators[validator_index].addr # Check that the commit is old enough assert self.current_epoch == block.number / self.epoch_length assert (self.current_epoch - epoch) * self.epoch_length * self.block_time > self.insufficiency_slash_delay assert not self.consensus_messages[epoch].hash_justified[hash] # Delete the offending validator, and give a 4% "finder's fee" validator_deposit = self.validators[validator_index].deposit send(msg.sender, validator_deposit / 25) self.total_destroyed += validator_deposit * 24 / 25 self.total_deposits[self.dynasty] -= validator_deposit self.validators[validator_index] = { deposit: 0, dynasty_start: 0, dynasty_end: 0, withdrawal_epoch: 0, addr: None, withdrawal_addr: None, max_prepared: 0, max_committed: 0, } # Fill in the table for which hash is what-degree ancestor of which other hash def derive_parenthood(older: bytes32, hash: bytes32, newer: bytes32): assert sha3(concat(hash, older)) == newer self.ancestry[older][newer] = 1 # Fill in the table for which hash is what-degree ancestor of which other hash def derive_ancestry(oldest: bytes32, middle: bytes32, recent: bytes32): assert self.ancestry[middle][recent] assert self.ancestry[oldest][middle] self.ancestry[oldest][recent] = self.ancestry[oldest][middle] + self.ancestry[middle][recent] def prepare_non_justification_slash(validator_index: num, prepare_msg: bytes <= 1024) -> num: # Get hash for signature, and implicitly assert that it is an RLP list # consisting solely of RLP elements sighash = extract32(raw_call(self.sighasher, prepare_msg, gas=200000, outsize=32), 0) # Extract parameters values = RLPList(prepare_msg, [num, bytes32, bytes32, num, bytes32, bytes]) epoch = values[0] hash = values[1] ancestry_hash = values[2] source_epoch = values[3] source_ancestry_hash = values[4] sig = values[5] # Check the signature assert ecrecover(sighash, extract32(sig, 0, type=num256), extract32(sig, 32, type=num256), extract32(sig, 64, type=num256)) == self.validators[validator_index].addr # Check that the view change is old enough assert self.current_epoch == block.number / self.epoch_length assert (self.current_epoch - epoch) * self.block_time * self.epoch_length > self.insufficiency_slash_delay # Check that the source ancestry hash not had enough prepares, OR that there is not the # correct ancestry link between the current ancestry hash and source ancestry hash c1 = self.consensus_messages[source_epoch].ancestry_hash_justified[source_ancestry_hash] if epoch - 1 > source_epoch: c2 = self.ancestry[source_ancestry_hash][ancestry_hash] == epoch - 1 - source_epoch else: c2 = source_ancestry_hash == ancestry_hash assert not (c1 and c2) # Delete the offending validator, and give a 4% "finder's fee" validator_deposit = self.validators[validator_index].deposit send(msg.sender, validator_deposit / 25) self.total_destroyed += validator_deposit * 24 / 25 self.total_deposits[self.dynasty] -= validator_deposit self.validators[validator_index] = { deposit: 0, dynasty_start: 0, dynasty_end: 0, withdrawal_epoch: 0, addr: None, withdrawal_addr: None, max_prepared: 0, max_committed: 0, } # Temporary backdoor for testing purposes (to allow recovering destroyed deposits) def owner_withdraw(): send(self.owner, self.total_destroyed) self.total_destroyed = 0 # Change backdoor address (set to zero to remove entirely) def change_owner(new_owner: address): if self.owner == msg.sender: self.owner = new_owner