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| # -*- coding: utf-8 -*- | |
| """Blockchain.ipynb | |
| Automatically generated by Colaboratory. | |
| Original file is located at | |
| https://colab.research.google.com/drive/1wfXS6MTMX2J77EP5X1qFiKQzdo_eh511 | |
| """ | |
| import datetime | |
| import hashlib | |
| import json | |
| class Blockchain: | |
| def __init__(self): | |
| self.chain = [] | |
| self.create_block(proof=1, previous_hash='0') | |
| def create_block(self, proof, previous_hash): | |
| block = {'index': len(self.chain) + 1, | |
| 'timestamp': str(datetime.datetime.now()), | |
| 'proof': proof, | |
| 'previous_hash': previous_hash} | |
| self.chain.append(block) | |
| return block | |
| def print_previous_block(self): | |
| return self.chain[-1] | |
| def proof_of_work(self, previous_proof): | |
| new_proof = 1 | |
| check_proof = False | |
| while check_proof is False: | |
| hash_operation = hashlib.sha256( | |
| str(new_proof**2 - previous_proof**2).encode()).hexdigest() | |
| if hash_operation[:5] == '00000': | |
| check_proof = True | |
| else: | |
| new_proof += 1 | |
| return new_proof | |
| def hash(self, block): | |
| encoded_block = json.dumps(block, sort_keys=True).encode() | |
| return hashlib.sha256(encoded_block).hexdigest() | |
| def chain_valid(self, chain): | |
| previous_block = chain[0] | |
| block_index = 1 | |
| while block_index < len(chain): | |
| block = chain[block_index] | |
| if block['previous_hash'] != self.hash(previous_block): | |
| return False | |
| previous_proof = previous_block['proof'] | |
| proof = block['proof'] | |
| hash_operation = hashlib.sha256( | |
| str(proof**2 - previous_proof**2).encode()).hexdigest() | |
| if hash_operation[:5] != '00000': | |
| return False | |
| previous_block = block | |
| block_index += 1 | |
| return True | |
| def create_chain(): | |
| global blockchain | |
| blockchain = Blockchain() | |
| return "Chain Instantiated" | |
| def del_chain(): | |
| global blockchain | |
| del blockchain | |
| return "Chain Deleted" | |
| def mine_block(): | |
| previous_block = blockchain.print_previous_block() | |
| previous_proof = previous_block['proof'] | |
| proof = blockchain.proof_of_work(previous_proof) | |
| previous_hash = blockchain.hash(previous_block) | |
| block = blockchain.create_block(proof, previous_hash) | |
| response = {'message': 'A block is MINED', | |
| 'index': block['index'], | |
| 'timestamp': block['timestamp'], | |
| 'proof': block['proof'], | |
| 'previous_hash': block['previous_hash']} | |
| return response | |
| def hack_block(index,value): | |
| index=int(index.split(" ")[1])-1 | |
| blockchain.chain[index]['proof']=value | |
| return f"block modified at index:{index+1}" | |
| def display_chain(): | |
| try: | |
| response = {'chain': blockchain.chain,'length': len(blockchain.chain)} | |
| except: | |
| response = "No chain found" | |
| return response | |
| def valid(): | |
| valid = blockchain.chain_valid(blockchain.chain) | |
| if valid: | |
| response = {'message': 'The Blockchain is valid.'} | |
| else: | |
| response = {'message': 'The Blockchain is not valid.'} | |
| return response | |
| import gradio as gr | |
| with gr.Blocks(title='Blockchain Simulator') as demo: | |
| gr.Image(value="./Blockchain.jpg",show_label=False,shape=(1500,300)) | |
| with gr.Row(): | |
| with gr.Column(scale=3): | |
| display = gr.Textbox(label="Blockchain Output",lines=5) | |
| dblock = gr.Button("Display/Refresh Blockchain") | |
| with gr.Column(scale=2): | |
| cblock = gr.Button("Instantiate Blockchain") | |
| mblock = gr.Button("Mine a Block") | |
| vblock = gr.Button("Validate Blockchain") | |
| delblock = gr.Button("Delete Blockchain") | |
| with gr.Column(scale=2): | |
| index = gr.Radio(choices=["index 1", "index 2", "index 3"],label="Choose an Index to hack") | |
| value = gr.Textbox(label="New Value", placeholder = "Enter a Value") | |
| hblock = gr.Button("Hack a Block") | |
| dblock.click(fn=display_chain, inputs=[], outputs=[display],show_progress=True) | |
| cblock.click(fn=create_chain, inputs=[], outputs=[display],show_progress=True) | |
| mblock.click(fn=mine_block, inputs=[], outputs=[display],show_progress=True) | |
| vblock.click(fn=valid, inputs=[], outputs=[display],show_progress=True) | |
| delblock.click(fn=del_chain, inputs=[], outputs=[display],show_progress=True) | |
| hblock.click(fn=hack_block, inputs=[index,value], outputs=[display],show_progress=True) | |
| demo.launch() |