Update app.py

app.py

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+import streamlit as st
+import hashlib
+import json
+import time
+import requests
+
+# IPFS API URL (Use a public IPFS gateway or set up your own node)
+IPFS_API_URL = "https://api.pinata.cloud/pinning/pinJSONToIPFS"
+IPFS_HEADERS = {
+    "pinata_api_key": "your_pinata_api_key",
+    "pinata_secret_api_key": "your_pinata_secret_api_key",
+}
+
+# Blockchain Class
+class Blockchain:
+    def __init__(self):
+        self.chain = []
+        self.voters = set()
+        self.load_data()
+
+    def create_block(self, votes, previous_hash):
+        block = {
+            "index": len(self.chain) + 1,
+            "timestamp": time.time(),
+            "votes": votes,
+            "previous_hash": previous_hash,
+            "hash": self.hash_block(votes, previous_hash)
+        }
+        ipfs_hash = self.upload_to_ipfs(block)
+        block["ipfs_hash"] = ipfs_hash  # Store IPFS hash
+        self.chain.append(block)
+        self.save_data()
+        return block
+
+    def hash_block(self, votes, previous_hash):
+        block_string = json.dumps(votes, sort_keys=True) + previous_hash
+        return hashlib.sha256(block_string.encode()).hexdigest()
+
+    def get_latest_block(self):
+        return self.chain[-1] if self.chain else None
+
+    def upload_to_ipfs(self, block):
+        """Uploads block data to IPFS and returns the IPFS hash."""
+        try:
+            response = requests.post(IPFS_API_URL, headers=IPFS_HEADERS, json={"pinataContent": block})
+            if response.status_code == 200:
+                return response.json()["IpfsHash"]
+            else:
+                return "Error uploading to IPFS"
+        except Exception as e:
+            return str(e)
+
+    def save_data(self):
+        with open("votes.json", "w") as f:
+            json.dump({"chain": self.chain, "voters": list(self.voters)}, f, indent=4)
+
+    def load_data(self):
+        try:
+            with open("votes.json", "r") as f:
+                data = json.load(f)
+                self.chain = data.get("chain", [])
+                self.voters = set(data.get("voters", []))
+        except FileNotFoundError:
+            self.chain = []
+            self.voters = set()
+
+# Initialize Blockchain
+blockchain = Blockchain()
+
+# Streamlit UI
+st.title("🗳 Blockchain-Based Voting System (IPFS-Enabled)")
+
+# Voter ID for uniqueness
+voter_id = st.text_input("Enter your Voter ID (Unique & Unchangeable)", max_chars=10)
+
+# Candidates
+candidates = ["Alice", "Bob", "Charlie"]
+selected_candidate = st.selectbox("Select a candidate to vote for:", candidates)
+
+# Voting Button
+if st.button("Vote"):
+    if not voter_id:
+        st.warning("⚠ Please enter a valid Voter ID!")
+    elif voter_id in blockchain.voters:
+        st.error("❌ You have already voted!")
+    else:
+        last_block = blockchain.get_latest_block()
+        new_votes = last_block["votes"].copy() if last_block else {}
+
+        new_votes[selected_candidate] = new_votes.get(selected_candidate, 0) + 1
+        blockchain.create_block(new_votes, last_block["hash"] if last_block else "0")
+        blockchain.voters.add(voter_id)
+        blockchain.save_data()
+        
+        st.success(f"✅ Vote cast for {selected_candidate}!")
+
+# Display Vote Count
+st.subheader("🔢 Live Vote Count")
+latest_block = blockchain.get_latest_block()
+if latest_block:
+    for candidate, votes in latest_block["votes"].items():
+        st.write(f"✅ {candidate}: {votes} votes")
+
+# Show Blockchain
+if st.checkbox("Show Blockchain Data"):
+    st.json(blockchain.chain)
+
+# Show IPFS Hashes for each Block
+st.subheader("🔗 IPFS Storage Links")
+if latest_block:
+    for block in blockchain.chain:
+        st.write(f"🔗 Block {block['index']} stored on IPFS: [View](https://gateway.pinata.cloud/ipfs/{block.get('ipfs_hash', 'N/A')})")