File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/app.py", line 1498, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/app.py", line 1476, in wsgi_app
    response = self.handle_exception(e)
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/app.py", line 1473, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/app.py", line 882, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/app.py", line 880, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/app.py", line 865, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)  # type: ignore[no-any-return]
  File "/Users/bkalpa/Desktop/Desktop/Capstone - 2/app.py", line 63, in view_messages
    return render_template('message.html', messages=user_messages, decrypt=decrypt)
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/templating.py", line 150, in render_template
    return _render(app, template, context)
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/flask/templating.py", line 131, in _render
    rv = template.render(context)
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/jinja2/environment.py", line 1304, in render
    self.environment.handle_exception()
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/jinja2/environment.py", line 939, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "/Users/bkalpa/Desktop/Desktop/Capstone - 2/templates/message.html", line 13, in top-level template code
    <strong>Decrypted Message:</strong> {{ decrypt(message['message'], base64.b64decode(message['key'])) }}<br>
  File "/Users/bkalpa/Library/Python/3.9/lib/python/site-packages/jinja2/environment.py", line 487, in getattr
    return getattr(obj, attribute)
jinja2.exceptions.UndefinedError: 'base64' is undefined

My code for:

app.py

from flask import Flask, render_template, request, redirect, url_for, session
import os
import base64

app = Flask(__name__)
app.secret_key = 'supersecretkey'

# In-memory storage for profiles and messages
profiles = {}
messages = []

# Generate a random key
def generate_key(length):
    return os.urandom(length)

# Encrypt the message
def encrypt(message, key):
    message_bytes = message.encode('utf-8')
    encrypted_bytes = bytes([mb ^ kb for mb, kb in zip(message_bytes, key)])
    return base64.b64encode(encrypted_bytes).decode('utf-8')

# Decrypt the message
def decrypt(encrypted_message, key):
    encrypted_bytes = base64.b64decode(encrypted_message.encode('utf-8'))
    decrypted_bytes = bytes([eb ^ kb for eb, kb in zip(encrypted_bytes, key)])
    return decrypted_bytes.decode('utf-8')

@app.route('/')
def index():
    return render_template('index.html', profiles=profiles)

@app.route('/create_profile', methods=['POST'])
def create_profile():
    username = request.form['username']
    if username not in profiles:
        profiles[username] = {'messages': []}
    return redirect(url_for('index'))

@app.route('/send_message', methods=['POST'])
def send_message():
    sender = request.form['sender']
    receiver = request.form['receiver']
    message = request.form['message']
    
    if receiver not in profiles:
        return "Receiver profile does not exist", 400

    key = generate_key(len(message))
    encrypted_message = encrypt(message, key)

    # Store the encrypted message and key with the receiver
    profiles[receiver]['messages'].append({'from': sender, 'message': encrypted_message, 'key': base64.b64encode(key).decode('utf-8')})
    
    return redirect(url_for('index'))

@app.route('/view_messages/<username>')
def view_messages(username):
    if username not in profiles:
        return "Profile does not exist", 400

    user_messages = profiles[username]['messages']
    return render_template('message.html', messages=user_messages, decrypt=decrypt)

if __name__ == '__main__':
    app.run(debug=True)

Index.html

<!DOCTYPE html>
<html>
<head>
    <title>One-Time Pad Encryption</title>
</head>
<body>
    <h1>Create Profile</h1>
    <form method="POST" action="/create_profile">
        <input type="text" name="username" placeholder="Username" required>
        <button type="submit">Create</button>
    </form>

    <h1>Send Message</h1>
    <form method="POST" action="/send_message">
        <select name="sender">
            {% for username in profiles %}
                <option value="{{ username }}">{{ username }}</option>
            {% endfor %}
        </select>
        <select name="receiver">
            {% for username in profiles %}
                <option value="{{ username }}">{{ username }}</option>
            {% endfor %}
        </select>
        <input type="text" name="message" placeholder="Message" required>
        <button type="submit">Send</button>
    </form>

    <h1>Profiles</h1>
    <ul>
        {% for username in profiles %}
            <li><a href="/view_messages/{{ username }}">{{ username }}</a></li>
        {% endfor %}
    </ul>
</body>
</html>

message.html

<!DOCTYPE html>
<html>
<head>
    <title>Messages</title>
</head>
<body>
    <h1>Messages</h1>
    <ul>
        {% for message in messages %}
            <li>
                <strong>From:</strong> {{ message['from'] }}<br>
                <strong>Encrypted Message:</strong> {{ message['message'] }}<br>
                <strong>Decrypted Message:</strong> {{ decrypt(message['message'], base64.b64decode(message['key'])) }}<br>
            </li>
        {% endfor %}
    </ul>
    <a href="/">Back</a>
</body>
</html>

Can you help me to debug this?