verification of the signature when a transaction is being submitted, UI JS code for blockchain_client

code-architect · code-architect · commit 823d8bf359ed · 2023-10-27T07:58:25.000+05:30
diff --git a/blockchain/blockchain.py b/blockchain/blockchain.py
@@ -1,7 +1,13 @@
+from Crypto.Hash import SHA
+from Crypto.PublicKey import RSA
 from flask import Flask, render_template, jsonify, request
 from time import time
 from flask_cors import CORS
 from collections import OrderedDict
+import binascii
+from Crypto.Signature import PKCS1_v1_5
+
+MINING_SENDER = "blockchain"
 
 
 class Blockchain:
@@ -26,22 +32,36 @@ def create_block(self, nonce, previous_hash):
         self.transactions = []
         self.chain.append(block)
 
-    def submit_transaction(self, sender_public_key, recipient_public_key, signature, amount):
-        # TODO: reward miner
-        # TODO: Signature validation
+    def verify_transaction_signature(self, sender_public_key, signature, transaction):
+        public_key = RSA.importKey(binascii.unhexlify(sender_public_key))
+        verifier = PKCS1_v1_5.new(public_key)
+        hash = SHA.new(str(transaction).encode('utf8'))
+        try:
+            verifier.verify(hash, binascii.unhexlify(signature))
+            return True
+        except ValueError:
+            return False
 
+    def submit_transaction(self, sender_public_key, recipient_public_key, signature, amount):
+        # Signature validation
         transaction = OrderedDict({
             'sender_public_key': sender_public_key,
             'recipient_public_key': recipient_public_key,
-            'signature': signature,
             'amount': amount,
         })
-        signature_verification = True
-        if signature_verification:
+
+        # reward for miner
+        if sender_public_key == MINING_SENDER:
             self.transactions.append(transaction)
             return len(self.chain) + 1
         else:
-            return False
+            # Transaction from wallet to another wallet
+            signature_verification = self.verify_transaction_signature(sender_public_key, signature, transaction)
+            if signature_verification:
+                self.transactions.append(transaction)
+                return len(self.chain) + 1
+            else:
+                return False
 
 
 blockchain = Blockchain()
@@ -60,7 +80,12 @@ def index():
 def transactions_new():
     values = request.form
 
-    # TODO: check required fields
+    # check required fields [Notes: This is just a demo, not production code, so not checking thoroughly, just doing
+    # basic checks]
+    required = ['confirmation_sender_public_key', 'confirmation_recipient_public_key', 'transaction_signature', 'confirmation_amount']
+    if not all(k in values for k in required):
+        return 'Missing Values', 400
+
     transaction_results = blockchain.submit_transaction(values['confirmation_sender_public_key'],
                                                         values['confirmation_recipient_public_key'],
                                                         values['transaction_signature'], values['confirmation_amount'])
diff --git a/blockchain_client/blockchain_client.py b/blockchain_client/blockchain_client.py
@@ -18,7 +18,6 @@ def __init__(self, sender_public_key, sender_private_key, recipient_public_key,
     def to_dict(self):
         return OrderedDict({
             'sender_public_key': self.sender_public_key,
-            'sender_private_key': self.sender_private_key,
             'recipient_public_key': self.recipient_public_key,
             'amount': self.amount,
         })
diff --git a/blockchain_client/templates/view_transactions.html b/blockchain_client/templates/view_transactions.html
@@ -0,0 +1,34 @@
+<!doctype html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport"
+          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
+    <meta http-equiv="X-UA-Compatible" content="ie=edge">
+    <title>Blockchain Front</title>
+    <link rel="stylesheet" href="static/vendor/bootstrap/css/bootstrap.min.css">
+    <link rel="stylesheet" href="/static/vendor/DataTables/css/datatables.min.css">
+    <link rel="stylesheet" href="/static/vendor/font-awesome/font-awesome.min.css">
+    <link rel="stylesheet" href="/static/css/custom.css">
+
+</head>
+<body style="background: linear-gradient(110deg, #fdcd3b 60%, #ffed4b 60%);">
+    <nav class="navbar navbar-expand-lg navbar-dark bg-dark fixed-top">
+        <div class="container">
+            <a href="#" class="navbar-brand">Blockchain Client</a>
+
+            <div class="collapse navbar-collapse">
+                <ul class="navbar-nav ml-auto">
+                    <li class="nav-item">
+                        <a href="/" class="nav-link">Wallet Generator</a>
+                    </li>
+                    <li class="nav-item active">
+                        <a href="/make_transaction" class="nav-link">Make Transaction</a>
+                    </li>
+                    <li class="nav-item">
+                        <a href="/view_transactions" class="nav-link">View transactions</a>
+                    </li>
+                </ul>
+            </div>
+        </div>
+    </nav>
