darkfi/script/research/dpos/ouroboros/stakeholder.py

from copy import deepcopy
import time
from ouroboros.block import Block, GensisBlock, EmptyBlock
from ouroboros.blockchain import Blockchain
from ouroboros.epoch import Epoch
from ouroboros.vrf import verify, VRF
from ouroboros.utils import *
from ouroboros.logger import Logger
from ouroboros.consts import *
from ouroboros.data import Data, Transaction, Item

'''
\class Stakeholder
'''
class Stakeholder(object):
    def __init__(self, epoch_length, passwd='password'):
        #TODO (fix) remove redundant variables reley on environment
        self.passwd=passwd
        self.stake=1
        self.epoch_length=epoch_length
        self.vrf = VRF(self.passwd)
        #verification keys
        self.__vrf_pk = self.vrf.pk
        self.__vrf_sk = self.vrf.sk
        self.__vrf_base = self.vrf.g
        #signature keys
        sig_sk, sig_pk = generate_sig_keys(self.passwd)
        self.sig_sk = sig_sk
        self.sig_pk = sig_pk
        #
        self.current_block = None
        self.current_epoch = None
        self.am_corrupt=False
        #
        self.blockchain=None
        #
        self.data = Data()
        #verifiable fingerprint for a stakeholder taking advantage of public sig, vrf
        self.id = sign_message(self.passwd, self.sig_sk, str(self.vrf_pk))

    def receive_tx(self, tx):
        #TODO validate trx
        self.data.append(tx)

    def broadcast_tx(self, tx):
        self.data.append(tx)
        self.env.broadcast_tx(tx)

    @property
    def vrf_pk(self):
        return self.__vrf_pk

    @property
    def vrf_base(self):
        return self.__vrf_base
    
    def __repr__(self):
        buff=''
        if self.env.is_current_leader(self.id):
            buff = f"\tleader {self.id} with stake:{self.stake}\nsig_pk: {self.sig_pk}"
        elif self.env.is_current_endorser(self.id):
            buff = f"\tendorser {self.id} with stake:{self.stake}\nsig_pk: {self.sig_pk}"
        else:
            buff = f"\thonest committee memeber {self.id} with stake:{self.stake}\nsig_pk: {self.sig_pk}"
        return buff

    def __call__(self, env):
        self.env=env
        self.log = Logger(self, self.env.genesis_time)
        self.blockchain = Blockchain(self.epoch_length, self.env.genesis_time)
        #self.beacon = TrustedBeacon(self,  self.vrf, self.epoch_length, self.env.genesis_time)
        #self.current_slot_uid = self.beacon.slot

    @property
    def epoch_index(self):
        return round(self.current_slot_uid/self.epoch_length)
        
    def end_slot(self):
        # start new transactions 
        self.data = Data()

    def add_epoch(self):
        self.blockchain.append(self.current_epoch)
        self.update_stake()
    
    def new_epoch(self, current_epoch):
        if self.current_epoch!=None:
            self.add_epoch()
        self.current_epoch = current_epoch

    def new_slot(self, slot, sigma, proof):
        self.log.highlight("<new_slot> start")
        vrf_pk = self.env.prev_leader_vrf_pk()
        vrf_g = self.env.prev_leader_vrf_g()
        self.log.highlight(f"verifying slot leader with pk: {str(vrf_pk)}, : {str(vrf_g)}")
        self.log.highlight(f"verifying slot {slot}\nsigma {sigma}\nproof {proof}\npk {vrf_pk} \nbase {vrf_g}")
        if not verify(slot, sigma, proof, vrf_pk, vrf_g):
            #TODO the leader is corrupted, action to be taken against the corrupt stakeholder
            #in this case this slot is empty
            self.log.warn(f"<new_slot> leader verification fails")
            self.current_block=EmptyBlock(self.env.genesis_time) 
            self.current_epoch.add_block(self.current_block)
            return
        self.current_slot_uid = slot
        if self.current_slot_uid%self.epoch_length!=0:
            prev_blk = self.blockchain[-1] if len(self.blockchain)>0 else EmptyBlock(self.env.genesis_time)
            self.current_block=Block(prev_blk, self.data, self.current_slot_uid, self.env.genesis_time)
            self.current_epoch.add_block(self.current_block)
        if self.env.is_current_leader(self.id):
            self.log.highlight(f"{str(self)} is broadcasting block")
            self.broadcast_block()
        elif self.env.is_current_endorser(self.id):
            self.log.highlight(f"{str(self)} is endorsing block")
            self.endorse_block()

    def update_stake(self):
        if len(self.blockchain)==0:
            return
        epoch = self.blockchain[-1]
        pall = epoch.coffee()
        leader_cnt=0
        endorser_cnt=0
        for blk in epoch:
            if blk.leader_id==self.id:
                leader_cnt+=1
            elif blk.endorser_id==self.id:
                endorser_cnt+=1
        self.stake += (self.env.beta * (endorser_cnt/self.env.endorser_len) + \
            (1-self.env.beta) * (leader_cnt/self.env.epoch_length)) * pall

    def set_corrupt(self):
        self.am_corrupt=False

    '''
    only leader can broadcast block
    '''
    def broadcast_block(self):
        if not self.env.is_current_leader(self.id):
            return
        self.current_block.set_leader(self.id)
        self.log.highlight("broadcasting block")
        assert self.env.is_current_leader(self.id) and self.current_block is not None
        signed_block=None
        #TODO should wait for l slot until block is endorsed
        endorsing_cnt=10
        #TODO (rev)
        while not self.current_block.endorsed or self.blockchain[self.current_slot_uid]:
            time.sleep(1)
            self.log.info("...waiting for endorsment..")
            endorsing_cnt-=1
        '''
        if not self.current_block.endorsed:
            self.log.warn("failure endorsing the block...")
            self.current_block = EmptyBlock(self.env.genesis_time)
        '''
        signed_block = sign_message(self.passwd, self.sig_sk, self.current_block)
        self.env.broadcast_block(self.current_block, signed_block, self.current_slot_uid)
    
    @property
    def current_slot(self):
        return self.env.beacon.current_slot

    '''
    only endorser can broadcast block
    '''
    def endorse_block(self):
        assert self.env.is_current_endorser(self.id)
        assert self.env.endorser_sig_pk(self.env.beacon.slot) == self.sig_pk, f' assertion failed for beacon slot {self.env.beacon.slot}, current_slot {self.current_slot}, lhs: {self.env.endorser_sig_pk(self.env.beacon.slot)},\nrhs: {self.sig_pk}\nleader\endorser ids {self.env.slot_committee[self.env.beacon.slot][0]}/{self.env.slot_committee[self.env.beacon.slot][1]}'
        #assert self.env.endorser_sig_pk(self.current_slot) == self.sig_pk, f'lsh: {self.env.endorser_sig_pk(self.current_slot)},\nrhs: {self.sig_pk}'
        self.current_block.set_endorser(self.id)
        self.log.info(f"endorsing block for current_leader_id: {self.env.current_leader_id}")
        if not self.env.is_current_endorser(self.id):
            self.log.warn("not endorser")
            return
        assert self.current_block is not None
        sig = sign_message(self.passwd, self.sig_sk, self.current_block)
        self.log.highlight(f'block to be endorsed  {str(self.current_block)}')
        self.log.highlight(f'block to be endorsed has slot_uid: {self.current_slot_uid}')
        self.log.highlight(f'block to be endorsed has sig_pk: {str(self.sig_pk)}')
        self.env.endorse_block(sig, self.current_slot_uid)

    def __get_blk(self, blk_uid):
        assert(blk_uid>=0)
        stashed=True
        cur_blk = self.current_block
        if blk_uid < len(self.blockchain):
            #TODO this assumes synced blockchain
            cur_blk = self.blockchain[blk_uid]
            self.log.warn(f"current block from blockchain: {(cur_blk)}")
            stashed=False
        self.log.info(f"current block : {str(cur_blk)}\tblock uid: {blk_uid}\tstashed: {stashed}")
        if cur_blk is None:
            self.log.warn(f"blk uid {blk_uid}, blockchain length: {len(self.blockchain)}")
            self.log.warn(f"requested block is None\nblk_uid: {blk_uid}, blockchain: {self.blockchain}")
            self.log.warn(f'block is none, current block is {str(self.current_block)} and current slot {self.current_slot_uid}, current block uid {blk_uid}, env slot {self.env.current_slot}, env blk {self.env.block_id}')
        while cur_blk is None:
            self.log.info("waiting for start of slot/epoch...")
            time.sleep(1)
        return cur_blk, stashed

    def receive_block(self, signed_block, endorser_sig, blk_uid):
        self.log.highlight("receiving block")
        cur_blk, stashed = self.__get_blk(blk_uid)
        #TODO to consider deley should retrive leader_pk of corresponding blk_uid
        self.log.highlight(f'receiving block  {str(cur_blk)}')
        self.log.highlight(f'receiving block has slot_uid: {self.current_slot_uid}')
        self.log.highlight(f'receiving block has sig_pk: {self.env.current_endorser_sig_pk}')
        blk_verified = verify_signature(self.env.current_leader_sig_pk, cur_blk, signed_block)
        self.log.info("endorser sig_pk {self.env.current_endorser_sig_pk}, cur_blk: {cur_blk}, endorser_sig: {endorser_sig}")
        blk_edrs_verified = verify_signature(self.env.current_endorser_sig_pk, cur_blk, endorser_sig)
        if blk_verified and blk_edrs_verified:
            if stashed:
                self.current_epoch.add_block(cur_blk)
        else:
            if not blk_verified:
                self.log.warn("block verification failed")
            elif not blk_edrs_verified:
                self.log.warn("block endorsing verification failed")
            self.env.corrupt_blk()

    def confirm_endorsing(self, endorser_sig, blk_uid, slot):
        self.log.highlight(f"confirming block with epoch slot id {blk_uid}")
        confirmed = False
        cur_blk, _ = self.__get_blk(blk_uid)
        self.log.highlight(f'confirming endorsed block  {str(cur_blk)}')
        self.log.highlight(f'confirming endorsed has slot: {slot} epoch slot_uid: {self.current_slot_uid}')
        self.log.highlight(f'confirming endorsed has sig_pk: {self.env.current_endorser_sig_pk}')
        endorser_sig_pk = self.env.endorser_sig_pk(self.env.beacon.slot)
        self.log.highlight(f'confirming endorsed sig pk: {endorser_sig_pk}')
        if verify_signature(endorser_sig_pk, cur_blk, endorser_sig):
            if self.current_slot_uid==self.env.current_slot:
                self.log.highlight("set current block as endorsed")
                self.current_block.set_endorser(self.env.current_endorser_uid)
                self.current_block.set_endorsed()
            else:
                self.log.highlight(f"set delayed blockchain block with uid: {blk_uid} as endorsed")
                self.blockchain[blk_uid].set_endorser(self.env.current_endorser_uid)
                self.blockchain[blk_uid].set_endorsed()
            confirmed=True
        else:
            self.log.warn(f"confirmed enderser signature failure for pk: {str(endorser_sig_pk)} on block {str(cur_blk)}  of signature {str(endorser_sig)}")
            confirmed=False
        return confirmed