Simple Python Blockchain Implementation - Simplecoin part 3

Namaste Friends,



Sorry For my late blog posts, Actually I'm still busy in studying blockchain and bitcoin concepts. So, Today, again I am going to share with you a new python script where I tried to add some more features in previous simple blockchain based ledger python script.

For Previous post

Part 1 :  check here
Part 2 : check here

Note

  • Tutorials And Reference For This Script Coming Soon...
  • Sorry For Less Comments And Bad Coding Styles.

Actually, Guys, I'm Still Busy In Developing This Script To Make More Advance, Adding More Features In It.
So, I'm Open For Suggestions Comments.

Some Key Features Of This Script.

  • Transactions Feature Supported
  • Transactions Merkle Data hashing Algorithm Supported
  • Proof Of Work Supported (hashcash)
  • Database created In Json To Make It More Simple To Understand
  • Python Object Orient Programming Basic Support


Requirements


  • PyCrypto Module
  • Python2.7
  • Currently Tested On Ubuntu Only


For More Details. Refer To my Github Repo. Check Here



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#!/usr/bin/python

__author__='''
        Suraj Singh bisht
        surajsinghbisht054@gmail.com
        www.bitforestinfo.com
        github.com/surajsinghbisht054


'''

# coding: utf-8

# In[9]:


import json
import os
from hashlib import sha256
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_v1_5
from hashlib import md5
from hashlib import sha256
from Crypto.Hash import SHA256
import binascii
import base64
import time


# In[10]:


#
# User Authentication Handling Class
#
class User:
    def __init__(self, private=None, public=None):
        '''
        A Simple Class To Handle User Authentication Activities
        
        '''
        
        if public:
            self.publickey = public
        else:
            self.publickey = ''
        
        if private:
            self.privatekey = RSA.importKey(private)
        else:
            (self.privatekey, self.address) = self.generate_key_pair()
        
    def generate_key_pair(self):
        '''
        Generate New Pair Of Keys For New Users 
        
        '''
        private = None
        public  = None

        # Random Number Generated
        random = RSA.Random.new().read
        PUB_LEN = 1024


        # RSA Object
        RSAKey = RSA.generate(PUB_LEN, random)

        # Private Key
        private = RSAKey.exportKey()

        # Public Key
        self.publickey =  RSAKey.publickey().exportKey()
        
        public = sha256(self.publickey).hexdigest()
        public = sha256(public).hexdigest()
        public = md5(public).hexdigest()
        
        return (private, public)
    
    def signature(self, data):
        '''
        Sign Data Using User Inserted/Generated Private Key
        '''
        
        r = RSA.importKey(self.privatekey)
        siger = PKCS1_v1_5.new(r)
        h = SHA256.new(data)
        return  binascii.hexlify(siger.sign(h))

#u = User()
#print u.publickey
#print u.privatekey
#print u.address
#print u.signature(u.address)


# In[11]:


# Global Functions

def previous_block_hash(blockitemdict):
    '''
    Global Function To Calculate previous block hashes
    '''
    return sha256("{index}{previoushash}{timestamp}{hash}{datahash}{nonce}{targetbit}".format(**blockitemdict)).hexdigest()

def transection_hash(data):
    '''
    Global Function To Calculate Transection hashes
    '''
    return sha256("{category}{txni}{coin}{fee}{signature}{time}".format(**data.getitems())).hexdigest() 

def merkle_hash(dataload):
    '''
     A Simple Class That Automatically Calculate Hashes Of All Transection feilds using
     Merkle Type Algorithm.
     
    '''
    
    # Two Empty Containers
    hl1 = [] 
    hl2 = [] 
    
    for data in dataload:
        hl1.append(transection_hash(data))
        
    if not hl1:
        return sha256('').hexdigest()
        
    while True:
        v1 = ''
        v2 = ''
        hl2 = []
        if int(len(hl1) % 2)==0 and len(hl1)>1:
          # Even Number's List
        
             for h in hl1:
                
                if not v1:
                    v1 = h
                    continue
                v2 = h
            
                hl2.append(sha256(v1+v2).hexdigest())
                v1 = ''
                v2 = ''
    
        elif int(len(hl1) % 2)==1 and len(hl1)>1:
            hl2 = hl1
            hl2.append('')
    
    
        elif len(hl1)==1:
            return hl1[0]
            
        else:
            return False

        hl1 = hl2        

    return False


# In[12]:


#
# trasenction feild structure
# (
#    category,  --> mine, send, receive
#    sender     --> Sender Wallet Address
#    receiver   --> Receiver Wallet Address
#    txni,      --> input transection
#    txno,      --> output transection
#    ccoin      --> net balance 
#    coin,      --> coin
#    fee,       --> transection fee
#    time,      --> time
#    signature, --> hash = sha256(category + sender + receiver + txni + txno + coin + fee + time)
#                   hash = private_key_signature(hash)
# 
#    
#    verification --> SENDER_PUBLIC_KEY
# )
#
# Trasenction Unique Identities
# 
# structure 
#   (
#
#         Name  :  SHA256( sender + receiver )   ---> Result Hash Will Be Same 
#                                                    if Sender and Reciever are same (Not Unique)
#         txnid :  SHA256( Name + Signature)       --> Always Unique
#    
#         txn : trasenction feild
#
#   )
#
#
#
#







# Simple Request Transection ()
class RequestTransection:
    def __init__(self, user):
        '''
         A Simple Class To Handle And Generate Valid Transection Requests 
         Using User Object Authentication Object.
         
        '''
        self.category   = ''
        self.user       = user
        self.sender     = None
        self.receiver   = None
        self.txni       = []
        self.ccoin      = ''
        self.coin       = ''
        self.time       = ''
        self.fee        = ''
        self.signature  = ''
        self.transection = {}
        self.verification = ''
        
    def getitems(self):
        '''
        Get All Feild Items
        '''
        return {
            "category" : self.category,  
            "txni"   : self.txni,
            "ccoin"  : self.ccoin,
            "coin"   : self.coin,
            "fee"      : self.fee,
            "signature"     : self.signature,
            "time"     : self.time,
            
        }
    
    def __repr__(self):
        return "< transReq {} | {} >".format(self.category, self.time)

    
    def create_transection(self, category='mine', txni=[], coin='', 
                           fee='', receiver = '', sender = ''):
        '''
        Generate Valid Transection Request With Automatic Hash And Signature handling
        '''
        if not sender:
            sender = self.user.address
            
        if category=="mine":
            sender =''
            receiver = self.user.address
            
        if not receiver:
            raise "please insert valid receiver address."
        
        # Lower case --- > category
        category = category.lower()
        
        # Check category
        if category not in ['mine', 'send']:
            raise "please use valid categories like mine or send "
            
            
        # initialise values
        self.category  = category
        self.sender    = sender
        self.receiver  = receiver
        self.txni      = ''.join(i for i in txni)
        self.coin      = coin
        self.fee       = fee
        self.time      = str(time.time())
        #
        #    signature, --> hash = sha256(category + sender + receiver + txni + coin + fee + time)
        #                   private_key_signature(hash)
        #
        h = self.category + self.sender + self.receiver + self.txni + self.coin + self.fee + self.time
        h = sha256(h).hexdigest()
        
        
        if self.category!="mine":
            self.verification = self.user.publickey
        
        self.signature = self.user.signature(h)
        
        self.transection = {
            "name" : sha256(self.sender + self.receiver).hexdigest(),
            "txn"  : sha256( sha256(self.sender + self.receiver).hexdigest() + self.signature).hexdigest(),
            "load" : self.getitems(),
            
        }
        return


# In[13]:


#
#
# RequestBlock Object handler
#
# Structure
# ( 
#     index         ---> current block index in chain
#     previoushash  ---> previous block hash
#     timestamp     ---> timestamp
#     targetbit     ---> difficulty bit in hash calculation
#     hash          ---> self block hash (proof of work)
#     datahash      ---> datahash (merkle hash of transection feilds)
#     dataload      ---> all transection data
#     nonce         ---> nonce (proof of work)
#  )
#
#
#
#
#
class RequestBlock:
    def __init__(self, index, previoushash, targetbit=4, transbuffer = []):
        '''
         A Simple Class To Handle All Transection Request And Generate A Valid Block.
        '''
        
        self.index       = index
        self.previoushash = previoushash
        self.timestamp   = str(time.time())
        self.targetbit   = targetbit
        self.hash        = ''
        self.datahash    = ''
        self.dataload    = []
        self.nonce       = ''
        self.transbuffer = transbuffer
        self.calculate_block()

        
    
    def calculate_block(self): 
        '''
        Calculate Block Hash
        '''
        # load transections from Node Buffer
        self.load_data_from_network_buffer()
        tmp = merkle_hash(self.dataload)
        if not tmp:
            print "[Note] No Data load Found"
        self.datahash = tmp
        return
    
        
    def load_data_from_network_buffer(self):
        '''
        Load Trasection Requests
        '''
        for trans_req in self.transbuffer:
            if trans_req not in self.dataload:
                self.dataload.append(trans_req)
        return
        
    def getitems(self):
        '''
        return items
        '''
        return {
            "index"       : self.index,
            "previoushash": self.previoushash,
            "timestamp"   : self.timestamp,
            "targetbit"   : self.targetbit,
            "hash"        : self.hash,
            "datahash"    : self.datahash,
            "dataload"    : [i.transection for i in self.dataload],
            "nonce"       : self.nonce,
        }


# In[14]:


#
# Class Design To Perform Proof Of Work Hash Calculations
#
class MineBlock:
    '''
    A Simple Class That will Automatically handle Block Mining And Other Important Stuff.
    
    '''
    def __init__(self):
        self.pow = False
        self.block = ''
        self.difficulty = 0
        
    def block_validator(self, block):
        # Check Index
        # Check PRevious hash
        # check timestamp
        # check merkle hash
        if merkle_hash(block.dataload):
            return True
        return False
    
    def load(self, block):
        '''
        Load Block
        '''
        if self.block_validator(block):
            self.block = block
            self.difficulty = int(self.block.targetbit)
            self.proof_of_work_number_generator()
            self.pow = True
            return True
        
        return False
    
    def getblock(self):
        return self.block
    
    def getitems(self):
        return self.block.getitems()
    
    def proof_of_work_number_generator(self):
        self.block.nonce = 0
        while sha256("{}{}{}{}{}".format(self.block.previoushash,self.block.datahash,self.block.timestamp,self.block.targetbit,self.block.nonce)).hexdigest()[:self.difficulty]!='0'*self.difficulty:
            self.block.nonce+= 1
        self.block.hash = sha256("{}{}{}{}{}".format(self.block.previoushash,self.block.datahash,self.block.timestamp,self.block.targetbit,self.block.nonce)).hexdigest()
        return self.block.nonce
    


# In[15]:


#
# Class To handle Block chain database and act as a central sever to handle all block request
#
class SimpleBlockChain:
    '''
    A Simple Class To Handle Block Chain Database.
    '''
    def __init__(self, dbname='ChainStore.json', targetbit = 4):
        self.targetbit = targetbit
        self.dbname = dbname
        
        # Check BlockChain Json Storage File
        if os.path.exists(self.dbname):
            self.chain  = json.load(open(self.dbname, 'r'))
        else:
            self.chain = {
                "blockchain": [],
                'lastupdate': time.time(),
            }
        
        
        # Check BlockChain Status    
        if not self.check_chain_len():
            
            # Add Genesis Block
            self.add_genesis_block()
        
        
    # add genesis block request
    def add_genesis_block(self):
        '''
        Add Genesis Block
        '''
        print "Add Genesis Block Request"
        tmpobj = RequestBlock(1,0)
        mineblock = MineBlock()
        mineblock.load(tmpobj)
        self.new_block_request(mineblock.getblock())
        return
    
    # New Blocking Join Request
    def new_block_request(self, block):
        '''
        New Block Request
        '''
        # Verify Block
        if self.validate_new_block(block):
            self.chain['blockchain'].append(block.getitems())
            
            print "[+] Request Block Verified."
        else:
            print "[Error] Request Block Is Not Valid."
        return
    
    
    # Validate New Block Before Joining It to main Chain
    def validate_new_block(self, block):
        '''
        Validate And Verify Various Hash Calculations
        '''
        # check target bit
        # check block index
        # check previous block hash
        # check Proof of work
        # check timestamp
        # check datahash
        
        diff = self.targetbit == int(block.targetbit)
        
        if self.check_chain_len()==0:
            previoushash = True
        
        else:
            previoushash = block.previoushash == previous_block_hash(self.pre_block())#sha256("{index}{previoushash}{timestamp}{hash}{datahash}{nonce}{targetbit}".format(**self.pre_block())).hexdigest()
        
        proof_of_work_hash = sha256("{previoushash}{datahash}{timestamp}{targetbit}{nonce}".format(**block.getitems())).hexdigest()[:block.targetbit]=='0'*block.targetbit
        
        timestamp = float(block.timestamp) < time.time()
        
        index = block.index == self.check_chain_len()+1
        
        datahash = merkle_hash(block.dataload)
        
        if previoushash and proof_of_work_hash and timestamp and index and datahash and diff:
            return True
        print previoushash 
        print proof_of_work_hash 
        print timestamp 
        print index 
        print datahash 
        print diff
        return False
        
    # Check block chain length
    def check_chain_len(self):
        return len(self.chain['blockchain'])
    
    def pre_block(self):
        return self.chain['blockchain'][-1]
        #return
        
    # save updates
    def close(self):
        f = open(self.dbname, 'w')
        self.chain['lastupdate']= time.time()
        json.dump(self.chain, f, sort_keys=True, indent=4, separators=(',', ': '))
        f.close()
        return
    
    
    
    


# In[18]:


# -----------------------------------------------------------
# ================= Global Object ===========================
# -----------------------------------------------------------
# Create Blockchain handler object
sbc = SimpleBlockChain() 

# ------------------------------------------------------------
# ==================== Miner =================================
# ------------------------------------------------------------


# Create User Authentication Object
u = User()

# Create First Transection And Get Miners Reward
req = RequestTransection(u)

#create_transection
req.create_transection(category='mine', coin='25', fee='0', receiver = u.address)

reward_trasection = req.transection



# assemble all transection and create a block object
reqblock = RequestBlock(
    index = sbc.check_chain_len()+1, 
    previoushash = previous_block_hash(sbc.pre_block()), 
    transbuffer=[req]
)

# Miner Object
mineblock = MineBlock()

# Load Block and find proof of work
mineblock.load(reqblock)


# print proof of work
mineblock.getitems()



# insert block object to blockchain handler
sbc.new_block_request(mineblock.getblock())

# Now, Our First Transection Is Complete..

# Now, Let's Try Second Transection Request By Any Node


# ------------------------------------------------------------
# ==================== Nodes =================================
# ------------------------------------------------------------

node = User()  # Example Node

# Create Transection Request object
n_address = node.address # Shared its receiving address with miners.. because at this time,
# miner is the only one account that contain 25 coins


# Miner Requested A Transection
req = RequestTransection(u)
req.create_transection(category='send', sender=u.address, receiver=n_address, coin='20',txni=reward_trasection['txn'])
transer_money_reference_ = req.transection


# Wait... To Add This Block... Miner Again Need To Use its Computational Power... So,,

# Create First Transection And Get Miners Reward
req1 = RequestTransection(u)  # 

#create_transection
req1.create_transection(category='mine', coin='25', fee='0', receiver = u.address)

reward_2_trasection = req1.transection


# assemble all transection and create a block object
reqblock = RequestBlock(
    index = sbc.check_chain_len()+1, 
    previoushash = previous_block_hash(sbc.pre_block()), 
    transbuffer=[req, req1]
)

# Miner Object
mineblock = MineBlock()

# Load Block and find proof of work
mineblock.load(reqblock)


# print proof of work
mineblock.getitems()



# insert block object to blockchain handler
sbc.new_block_request(mineblock.getblock())

sbc.close()

To Run This Script.
Just Type:


$ python path/to/script.py

Blockchain JSON Output



{
    "blockchain": [
        {
            "datahash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
            "dataload": [],
            "hash": "000052310a4d3de6ee472d732681a44fee20bf6a5e1d4c804db3698d74773ae4",
            "index": 1,
            "nonce": 46130,
            "previoushash": 0,
            "targetbit": 4,
            "timestamp": "1527104534.07"
        },
        {
            "datahash": "5052de176f294ec4a653c412017d6be2a25a0bf61060b7ceaf921eade8c8fea4",
            "dataload": [
                {
                    "load": {
                        "category": "mine",
                        "ccoin": "",
                        "coin": "25",
                        "fee": "0",
                        "signature": "426371426864bc1c533eab894ecc97564be2cc3efe6473da10556e15aeff9626bc6a38283d5ae5b604977710c36be6c31fef68a1d5423690329d11af806c1068dbb4ed46ded5228d5f2858b908c2c56f7f9825bb23e74a33393f1ce83fc619ed80c4dc99844de13c052f170a4ff84d4144831f42dad9104298c00f243afccfc3",
                        "time": "1527104534.24",
                        "txni": ""
                    },
                    "name": "5355f59a8bc194a061de7bc8477f7a9b30279438a55964fd3db0c5a6ce3635ce",
                    "txn": "0fba77b217f80aa8010dc2c59e61b0525be42c688efb46db8c6528b33a2baf54"
                }
            ],
            "hash": "0000a7b48edc29d16f8765b5f6a2934f37823287171ff4ec8d205fa845b1bfb9",
            "index": 2,
            "nonce": 67206,
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