Initial commit

Dockerfile

@@ -0,0 +1,17 @@
+# docker build -t death-code .
+# docker run -d --restart unless-stopped --name death-code -p 2020:80 death-code
+# curl 127.0.0.1:2020
+
+FROM tiangolo/uwsgi-nginx-flask:python3.8
+LABEL maintainer="Andrew Dinh <death-code@andrewkdinh.com>"
+LABEL version="0.3.0"
+
+EXPOSE 80
+
+ADD ./requirements.txt /app/requirements.txt
+RUN python3 -m pip install --upgrade pip && python3 -m pip install -r /app/requirements.txt
+
+ADD ./templates /app/templates/
+ADD ./main.py /app/main.py
+
+HEALTHCHECK CMD curl http://localhost

LICENSE

@@ -658,4 +658,4 @@ specific requirements.
   You should also get your employer (if you work as a programmer) or school,
 if any, to sign a "copyright disclaimer" for the program, if necessary.
 For more information on this, and how to apply and follow the GNU AGPL, see
-<https://www.gnu.org/licenses/>.
+<https://www.gnu.org/licenses/>.

README.md

@@ -0,0 +1,25 @@
+# Death Code
+
+Death Code is an entirely self-hosted web application that utilizes [Sharmir's Secret Sharing](https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing) to share secrets after you die. After splitting a secret among a group of people, the secret can only be reconstructed when a sufficient number of people combine their parts together, presumably only after you are gone from this earth. 
+
+## Building
+
+1. Install `git`, `docker`, and `docker-compose`
+2. 
+
+```bash
+git clone https://github.com/andrewkdinh/death-code.git
+cd death-code
+cp .env.example .env
+# Edit .env
+git clone https://github.com/daniel-e/rust-captcha.git rust-captcha
+docker-compose up -d
+```
+
+## Credits
+
+- Built with Python Flask and Docker
+
+Mirrors: [GitHub](https://github.com/andrewkdinh/death-code) (main), [Gitea](https://gitea.andrewkdinh.com/andrewkdinh/death-code)
+
+Licensed under [AGPL](./LICENSE) | Copyright (c) 2021 Andrew Dinh

docker-compose.yml

@@ -0,0 +1,24 @@
+version: '3.0'
+services:
+  death-code:
+    container_name: death-code
+    build:
+      context: .
+    restart: unless-stopped
+    ports:
+      - 33284:80
+    depends_on: 
+      - rust-captcha
+    environment:
+      - END_URL=${END_URL} # If attempt is successful, redirect to this URL
+      - DOMAIN=${DOMAIN} # The domain this will be hosted on
+      - COEFFICIENTS_AND_MOD=${COEFFICIENTS_AND_MOD} # For example, [3, 5, 23] represents the function f(x)=3x+5 mod 23
+      - ALIVE_PATH=${ALIVE_PATH} # Path to deny allowing attempts immediately and start the countdown (optional)
+      - DAYS_TO_ALLOW=${DAYS_TO_ALLOW} # How many days to GET alive endpoint until death code starts allowing attemps (optional)
+      - DEAD_PATH=${DEAD_PATH} # Path to start allowing attemps immediately (optional)
+  rust-captcha:
+    container_name: rust-captcha
+    build:
+      context: ./rust-captcha/docker
+    restart: unless-stopped
+    

main.py

@@ -0,0 +1,176 @@
+#!/usr/bin/env python3
+
+from flask import Flask, render_template, redirect, request
+import requests
+from typing import List
+from datetime import datetime
+import os
+import json
+
+END_URL = os.getenv('END_URL')
+COEFFICIENTS_AND_MOD = json.loads(os.getenv('COEFFICIENTS_AND_MOD')) # For example, [3, 5, 23] represents the function f(x)=3x+5 mod 23
+DOMAIN = os.getenv('DOMAIN')
+DAYS_TO_ALLOW = os.getenv('DAYS_TO_ALLOW') # How many days to GET endpoint until death code functions
+if DAYS_TO_ALLOW:
+    DAYS_TO_ALLOW = int(DAYS_TO_ALLOW)
+# DAYS_TO_ALLOW = 7
+ALIVE_PATH = os.getenv('ALIVE_PATH') # Path to deny allowing attempts immediately and start the countdown (optional)
+# ALIVE_PATH = "i-am-alive"
+DEAD_PATH = os.getenv('DEAD_PATH') # Path to start allowing attemps immediately (optional)
+# DEAD_PATH = "i-am-dead"
+
+LAST_ENDPOINT_GET: datetime = None
+
+app = Flask(__name__)
+
+@app.route("/", methods=["GET", "POST"])
+def index():
+    global POLYNOMIAL, LAST_ENDPOINT_GET, DAYS_TO_ALLOW
+    if request.method == "POST":
+        if ALIVE_PATH and DAYS_TO_ALLOW and LAST_ENDPOINT_GET and (datetime.today() - LAST_ENDPOINT_GET).days < DAYS_TO_ALLOW:
+            return render_template("message.html", message="Andrew is still alive. Try again another time")
+        captcha_id = request.form.get('captcha-id')
+        captcha_solution = request.form.get('captcha-solution')
+        v = captcha_validate(captcha_id, captcha_solution)
+        if not v[0]:
+            return render_template('message.html', message = "Failed captcha", attempts_left = v[1])
+        try:
+            coords = []
+            for key in request.form:
+                if 'x' == key[0]:
+                    coords.append(Coordinate(int(request.form[key]), int(request.form['y' + key[1]])))
+            if POLYNOMIAL.valid_combination(coords):
+                return render_template("congrats.html", polynomial=POLYNOMIAL, domain=DOMAIN)
+            return render_template("message.html", message="Those points weren't valid", attempts_left = v[1])
+        except Exception as e:
+            print(e)
+            return render_template("message.html", message="Invalid data")
+    captcha = captcha_get(ttl = 300)
+    return render_template("index.html", polynomial = POLYNOMIAL, captcha_id = captcha[0], captcha_png = captcha[1])
+
+@app.route("/<attempt_num>", methods=["GET", "POST"])
+def attempt(attempt_num):
+    global POLYNOMIAL, LAST_ENDPOINT_GET, DAYS_TO_ALLOW
+    try:
+        attempt_num = int(attempt_num)
+        if request.method == "POST":
+            captcha_id = request.form.get('captcha-id')
+            captcha_solution = request.form.get('captcha-solution')
+            v = captcha_validate(captcha_id, captcha_solution)
+            if v[0]:
+                if ALIVE_PATH and  LAST_ENDPOINT_GET and (datetime.today() - LAST_ENDPOINT_GET).days < DAYS_TO_ALLOW:
+                    return render_template("message.html", message="Andrew is still alive. Try again another time")
+                num = int(attempt_num)
+                if num == POLYNOMIAL.x_zero_point:
+                    return redirect(END_URL, code=302)
+                return render_template('message.html', message="Incorrect guess for f(0)", attempts_left = v[1])
+            return render_template('message.html', message="Failed captcha", attempts_left = v[1])
+        captcha = captcha_get(ttl = 30, difficulty="hard")
+        return render_template('attempt.html', captcha_id = captcha[0], captcha_png = captcha[1])
+    except ValueError as e:
+        print(e)
+        return render_template('message.html', message="URL path must be an integer")
+    except Exception as e:
+        print(e)
+        return render_template('message.html', message="Error ocurred")
+
+if ALIVE_PATH and DAYS_TO_ALLOW:
+    @app.route("/" + ALIVE_PATH, methods=["GET"])
+    def am_alive():
+        global LAST_ENDPOINT_GET
+        LAST_ENDPOINT_GET = datetime.today()
+        return "OK"
+
+    if DEAD_PATH:
+        @app.route("/" + DEAD_PATH, methods=["GET"])
+        def am_dead():
+            global LAST_ENDPOINT_GET
+            LAST_ENDPOINT_GET = None
+            return "OK"
+
+def captcha_validate(captcha_id: str, captcha_solution: str) -> List:
+    """ Validates a captcha and returns [success, trials_left] """
+    response = requests.post(f"http://rust-captcha:8000/solution/{captcha_id}/{captcha_solution}", headers={'X-Client-ID': 'Death Code'}).json()
+    if response["error_code"] != 0:
+        print(f"http://rust-captcha:8000/solution/{captcha_id}/{captcha_solution}")
+        raise Exception(response)
+    if response["result"]["solution"] == "accepted":
+        return [True, 0]
+    return [False, response["result"]["trials_left"]]
+
+def captcha_get(max_tries: int = 3, ttl: int = 120, difficulty: str = "medium") -> List[str]:
+    """ Creates a captcha and returns [id, base64 encoded png] """
+    response = requests.post(f"http://rust-captcha:8000/new/{difficulty}/{max_tries}/{ttl}", headers={'X-Client-ID': 'Death Code'}).json()
+    if response["error_code"] != 0:
+        raise Exception(response)
+    return [response["result"]["id"], response["result"]["png"]]
+
+class Coordinate:
+    def __init__(self, x: int, y: int):
+        self.x = x
+        self.y = y
+    
+    def __repr__(self) -> str:
+        return "({}, {})".format(self.x, self.y)
+
+    def equals(self, coord):
+        """ Returns whether this coordinate is equal to the other """
+        return self.x == coord.x and self.y == coord.y
+
+class Polynomial:
+    def __init__(self, coefficients: List, modulo: int):
+        while (coefficients[0] == 0):
+            coefficients = coefficients[1:]
+
+        self.degree = len(coefficients) - 1
+        self.coefficients = coefficients
+        self.modulo = modulo
+        self.x_zero_point = coefficients[-1] % modulo
+
+    def __repr__(self):
+        i = 0
+        s = "y="
+        exponent = self.degree
+        while exponent > 1:
+            if s != "y=":
+                s += "+"
+            s += str(self.coefficients[i]) + "x^" + str(exponent)
+            exponent -= 1
+            i += 1
+        if i != len(self.coefficients):
+            if s != "y=":
+                s += "+"
+            s += str(self.coefficients[i]) + "x"
+            i += 1
+        if i != len(self.coefficients):
+            if s != "y=":
+                s += "+"
+            s += str(self.coefficients[-1])
+        return s + " mod " + str(self.modulo)
+
+    def valid_combination(self, coordinates: List[Coordinate]) -> bool:
+        """ Returns whether there are enough valid coordinates in `coordinates` to extract this polyomial """
+        count = 0
+        seen_coords = []
+        for coord in coordinates:
+            if self.valid_coord(coord) and all([not coord.equals(coordinate) for coordinate in seen_coords]):
+                count += 1
+                seen_coords.append(coord)
+        return count >= self.degree + 1
+    
+    def valid_coord(self, coord: Coordinate) -> bool:
+        """ Returns whether `coord` is a valid coordinate for this polynomial """
+        exponent = self.degree
+        coefficients = self.coefficients
+        value = 0
+        i = 0
+        while exponent >= 0:
+            value += coefficients[i] * pow(coord.x, exponent)
+            exponent -= 1
+            i += 1
+        return value % self.modulo == coord.y
+
+POLYNOMIAL = Polynomial(COEFFICIENTS_AND_MOD[:-1], COEFFICIENTS_AND_MOD[-1])
+
+if __name__ == "__main__":
+    app.run(host="0.0.0.0", debug=True, port=8888)

requirements.txt

@@ -0,0 +1,2 @@
+Flask~=1.1.2
+requests~=2.25.1

templates/attempt.html

@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <title>Death Code</title>
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+
+    <!-- water.css -->
+    <style>
+      body{font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;line-height:1.4;max-width:800px;margin:20px auto;padding:0 10px;color:#dbdbdb;background:#202b38;text-rendering:optimizeLegibility}button,input,textarea{transition:background-color .1s linear,border-color .1s linear,color .1s linear,box-shadow .1s linear,transform .1s ease}h1{font-size:2.2em;margin-top:0}h1,h2,h3,h4,h5,h6{margin-bottom:12px}h1,h2,h3,h4,h5,h6,strong{color:#fff}b,h1,h2,h3,h4,h5,h6,strong,th{font-weight:600}blockquote{border-left:4px solid rgba(0,150,191,.67);margin:1.5em 0;padding:.5em 1em;font-style:italic}blockquote>footer{margin-top:10px;font-style:normal}address,blockquote cite{font-style:normal}a[href^=mailto]:before{content:"📧 "}a[href^=tel]:before{content:"📞 "}a[href^=sms]:before{content:"💬 "}button,input[type=button],input[type=checkbox],input[type=submit]{cursor:pointer}input:not([type=checkbox]):not([type=radio]),select{display:block}button,input,select,textarea{color:#fff;background-color:#161f27;font-family:inherit;font-size:inherit;margin-right:6px;margin-bottom:6px;padding:10px;border:none;border-radius:6px;outline:none}button,input:not([type=checkbox]):not([type=radio]),select,textarea{-webkit-appearance:none}textarea{margin-right:0;width:100%;box-sizing:border-box;resize:vertical}button,input[type=button],input[type=submit]{padding-right:30px;padding-left:30px}button:hover,input[type=button]:hover,input[type=submit]:hover{background:#324759}button:focus,input:focus,select:focus,textarea:focus{box-shadow:0 0 0 2px rgba(0,150,191,.67)}button:active,input[type=button]:active,input[type=checkbox]:active,input[type=radio]:active,input[type=submit]:active{transform:translateY(2px)}button:disabled,input:disabled,select:disabled,textarea:disabled{cursor:not-allowed;opacity:.5}::-webkit-input-placeholder{color:#a9a9a9}:-ms-input-placeholder{color:#a9a9a9}::-ms-input-placeholder{color:#a9a9a9}::placeholder{color:#a9a9a9}a{text-decoration:none;color:#41adff}a:hover{text-decoration:underline}code,kbd{background:#161f27;color:#ffbe85;padding:5px;border-radius:6px}pre>code{padding:10px;display:block;overflow-x:auto}img{max-width:100%}hr{border:none;border-top:1px solid #dbdbdb}table{border-collapse:collapse;margin-bottom:10px;width:100%}td,th{padding:6px;text-align:left}th{border-bottom:1px solid #dbdbdb}tbody tr:nth-child(2n){background-color:#161f27}::-webkit-scrollbar{height:10px;width:10px}::-webkit-scrollbar-track{background:#161f27;border-radius:6px}::-webkit-scrollbar-thumb{background:#324759;border-radius:6px}::-webkit-scrollbar-thumb:hover{background:#415c73}
+    </style>
+</head>
+<body>
+    <p>Do this captcha because I don't trust y'all (captcha only valid for 30 seconds)</p>
+    <form method="POST">
+        <img src="data:image/png;base64, {{ captcha_png }}" />
+        <input required type="text" name="captcha-solution">
+        <input type="hidden" name="captcha-id" value="{{ captcha_id }}">
+        <button type="submit">Validate</button>
+    </form>
+</body>
+</html>

templates/congrats.html

@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <title>Death Code</title>
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+
+    <!-- water.css -->
+    <style>
+      body{font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;line-height:1.4;max-width:800px;margin:20px auto;padding:0 10px;color:#dbdbdb;background:#202b38;text-rendering:optimizeLegibility}button,input,textarea{transition:background-color .1s linear,border-color .1s linear,color .1s linear,box-shadow .1s linear,transform .1s ease}h1{font-size:2.2em;margin-top:0}h1,h2,h3,h4,h5,h6{margin-bottom:12px}h1,h2,h3,h4,h5,h6,strong{color:#fff}b,h1,h2,h3,h4,h5,h6,strong,th{font-weight:600}blockquote{border-left:4px solid rgba(0,150,191,.67);margin:1.5em 0;padding:.5em 1em;font-style:italic}blockquote>footer{margin-top:10px;font-style:normal}address,blockquote cite{font-style:normal}a[href^=mailto]:before{content:"📧 "}a[href^=tel]:before{content:"📞 "}a[href^=sms]:before{content:"💬 "}button,input[type=button],input[type=checkbox],input[type=submit]{cursor:pointer}input:not([type=checkbox]):not([type=radio]),select{display:block}button,input,select,textarea{color:#fff;background-color:#161f27;font-family:inherit;font-size:inherit;margin-right:6px;margin-bottom:6px;padding:10px;border:none;border-radius:6px;outline:none}button,input:not([type=checkbox]):not([type=radio]),select,textarea{-webkit-appearance:none}textarea{margin-right:0;width:100%;box-sizing:border-box;resize:vertical}button,input[type=button],input[type=submit]{padding-right:30px;padding-left:30px}button:hover,input[type=button]:hover,input[type=submit]:hover{background:#324759}button:focus,input:focus,select:focus,textarea:focus{box-shadow:0 0 0 2px rgba(0,150,191,.67)}button:active,input[type=button]:active,input[type=checkbox]:active,input[type=radio]:active,input[type=submit]:active{transform:translateY(2px)}button:disabled,input:disabled,select:disabled,textarea:disabled{cursor:not-allowed;opacity:.5}::-webkit-input-placeholder{color:#a9a9a9}:-ms-input-placeholder{color:#a9a9a9}::-ms-input-placeholder{color:#a9a9a9}::placeholder{color:#a9a9a9}a{text-decoration:none;color:#41adff}a:hover{text-decoration:underline}code,kbd{background:#161f27;color:#ffbe85;padding:5px;border-radius:6px}pre>code{padding:10px;display:block;overflow-x:auto}img{max-width:100%}hr{border:none;border-top:1px solid #dbdbdb}table{border-collapse:collapse;margin-bottom:10px;width:100%}td,th{padding:6px;text-align:left}th{border-bottom:1px solid #dbdbdb}tbody tr:nth-child(2n){background-color:#161f27}::-webkit-scrollbar{height:10px;width:10px}::-webkit-scrollbar-track{background:#161f27;border-radius:6px}::-webkit-scrollbar-thumb{background:#324759;border-radius:6px}::-webkit-scrollbar-thumb:hover{background:#415c73}
+    
+      body {
+        background-color: #ff75ff;
+        color: black;
+      }
+
+      a {
+        color: rgb(0, 47, 255);
+      }
+    </style>
+</head>
+<body>
+  <p>Congrats, you got it! The polynomial is {{ polynomial }} and the point at x=0 is {{ polynomial.x_zero_point }}. </p>
+    
+  <p>Now, visit <a rel="noopener noreferrer" href="/{{ polynomial.x_zero_point }}">https://{{ domain }}/{{ polynomial.x_zero_point }}</a></p>
+
+  <p>(A pink background just for you Vicki!)</p>
+</body>
+</html>

templates/index.html

@@ -0,0 +1,62 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <title>Death Code</title>
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+
+    <!-- water.css -->
+    <style>
+      body{font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;line-height:1.4;max-width:800px;margin:20px auto;padding:0 10px;color:#dbdbdb;background:#202b38;text-rendering:optimizeLegibility}button,input,textarea{transition:background-color .1s linear,border-color .1s linear,color .1s linear,box-shadow .1s linear,transform .1s ease}h1{font-size:2.2em;margin-top:0}h1,h2,h3,h4,h5,h6{margin-bottom:12px}h1,h2,h3,h4,h5,h6,strong{color:#fff}b,h1,h2,h3,h4,h5,h6,strong,th{font-weight:600}blockquote{border-left:4px solid rgba(0,150,191,.67);margin:1.5em 0;padding:.5em 1em;font-style:italic}blockquote>footer{margin-top:10px;font-style:normal}address,blockquote cite{font-style:normal}a[href^=mailto]:before{content:"📧 "}a[href^=tel]:before{content:"📞 "}a[href^=sms]:before{content:"💬 "}button,input[type=button],input[type=checkbox],input[type=submit]{cursor:pointer}input:not([type=checkbox]):not([type=radio]),select{display:block}button,input,select,textarea{color:#fff;background-color:#161f27;font-family:inherit;font-size:inherit;margin-right:6px;margin-bottom:6px;padding:10px;border:none;border-radius:6px;outline:none}button,input:not([type=checkbox]):not([type=radio]),select,textarea{-webkit-appearance:none}textarea{margin-right:0;width:100%;box-sizing:border-box;resize:vertical}button,input[type=button],input[type=submit]{padding-right:30px;padding-left:30px}button:hover,input[type=button]:hover,input[type=submit]:hover{background:#324759}button:focus,input:focus,select:focus,textarea:focus{box-shadow:0 0 0 2px rgba(0,150,191,.67)}button:active,input[type=button]:active,input[type=checkbox]:active,input[type=radio]:active,input[type=submit]:active{transform:translateY(2px)}button:disabled,input:disabled,select:disabled,textarea:disabled{cursor:not-allowed;opacity:.5}::-webkit-input-placeholder{color:#a9a9a9}:-ms-input-placeholder{color:#a9a9a9}::-ms-input-placeholder{color:#a9a9a9}::placeholder{color:#a9a9a9}a{text-decoration:none;color:#41adff}a:hover{text-decoration:underline}code,kbd{background:#161f27;color:#ffbe85;padding:5px;border-radius:6px}pre>code{padding:10px;display:block;overflow-x:auto}img{max-width:100%}hr{border:none;border-top:1px solid #dbdbdb}table{border-collapse:collapse;margin-bottom:10px;width:100%}td,th{padding:6px;text-align:left}th{border-bottom:1px solid #dbdbdb}tbody tr:nth-child(2n){background-color:#161f27}::-webkit-scrollbar{height:10px;width:10px}::-webkit-scrollbar-track{background:#161f27;border-radius:6px}::-webkit-scrollbar-thumb{background:#324759;border-radius:6px}::-webkit-scrollbar-thumb:hover{background:#415c73}
+
+      input:not([type="checkbox"]):not([type="radio"]), select {
+        display: initial;
+      }
+    </style>
+</head>
+<body>
+  <h1>Death Code</h1>
+  <hr />
+  <p>The polynomial is degree {{ polynomial.degree }}, so you'll need at least {{ polynomial.degree + 1 }} points to find it</p>
+
+  <form action="/" method="POST">
+    {% for i in range(polynomial.degree + 1) %}
+    <div>
+      <input required type="number" name="x{{i+1}}" placeholder="x{{i+1}}">
+      <input required type="number" name="y{{i+1}}" placeholder="y{{i+1}}">
+    </div>
+    {% endfor %}
+    <div style="padding: 5px 0">
+      <img src="data:image/png;base64, {{ captcha_png }}" />
+    </div>
+    <input required type="text" name="captcha-solution">
+    <input type="hidden" name="captcha-id" value="{{ captcha_id }}">
+    <button type="submit">Validate</button>
+  </form>
+  <p>Once you get the value of f(0), go to https://rip.andrewkdinh.com/f(0)</p>
+
+  <hr />
+  <p>Here's resources with more information (for now, just contact info for others with a coordinate). Password should've been given to you</p>
+
+  <ul>
+    <li><a target="_blank" rel="noopener noreferrer" href="https://nextcloud.andrewkdinh.com/s/ADmFKLCZgdycRH8">Nextcloud</a></li>
+    <li><a target="_blank" rel="noopener noreferrer" href="https://nextcloud.abhikahuja.com/s/TajPLXWLEkPQq6y">Abhik Ahuja's Nextcloud</a></li>
+    <li>
+      <details>
+      <summary><a target="_blank" rel="noopener noreferrer" href="https://mega.nz/folder/r44kgQCA">MEGA</a></summary>
+      <p>Decryption key: <code>echo "U2FsdGVkX1/fG6A2L6D50C2kCsrMw/sVdrjxJF7SfLy5z/92gR3So4LXBm8CYl3K"|openssl base64 -d|openssl enc -d -pbkdf2 -aes-256-cbc -k "PASSWORD_HERE"</code></p>
+      </details>
+    </li>
+  </ul>
+
+  <hr />
+  <p>Some other tools to do <a target="_blank" rel="noopener noreferrer" href="https://en.wikipedia.org/wiki/Polynomial_interpolation">Lagrange/polynomial interpolation</a>:</p>
+  <ul>
+    <li><a target="_blank" rel="noopener noreferrer" href="https://tools.timodenk.com/polynomial-interpolation">Timo Denk</a></li>
+    <li><a target="_blank" rel="noopener noreferrer" href="https://www.dcode.fr/lagrange-interpolating-polynomial">dCode</a></li>
+    <li><a target="_blank" rel="noopener noreferrer" href="https://www.wolframalpha.com/input/?i=interpolating+polynomial+calculator">WolframAlpha</a></li>
+    <li><a target="_blank" rel="noopener noreferrer" href="https://planetcalc.com/8692/">PlanetCalc</a></li>
+  </ul>
+</body>
+</html>

templates/message.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <title>Death Code</title>
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+
+    <!-- water.css -->
+    <style>
+      body{font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;line-height:1.4;max-width:800px;margin:20px auto;padding:0 10px;color:#dbdbdb;background:#202b38;text-rendering:optimizeLegibility}button,input,textarea{transition:background-color .1s linear,border-color .1s linear,color .1s linear,box-shadow .1s linear,transform .1s ease}h1{font-size:2.2em;margin-top:0}h1,h2,h3,h4,h5,h6{margin-bottom:12px}h1,h2,h3,h4,h5,h6,strong{color:#fff}b,h1,h2,h3,h4,h5,h6,strong,th{font-weight:600}blockquote{border-left:4px solid rgba(0,150,191,.67);margin:1.5em 0;padding:.5em 1em;font-style:italic}blockquote>footer{margin-top:10px;font-style:normal}address,blockquote cite{font-style:normal}a[href^=mailto]:before{content:"📧 "}a[href^=tel]:before{content:"📞 "}a[href^=sms]:before{content:"💬 "}button,input[type=button],input[type=checkbox],input[type=submit]{cursor:pointer}input:not([type=checkbox]):not([type=radio]),select{display:block}button,input,select,textarea{color:#fff;background-color:#161f27;font-family:inherit;font-size:inherit;margin-right:6px;margin-bottom:6px;padding:10px;border:none;border-radius:6px;outline:none}button,input:not([type=checkbox]):not([type=radio]),select,textarea{-webkit-appearance:none}textarea{margin-right:0;width:100%;box-sizing:border-box;resize:vertical}button,input[type=button],input[type=submit]{padding-right:30px;padding-left:30px}button:hover,input[type=button]:hover,input[type=submit]:hover{background:#324759}button:focus,input:focus,select:focus,textarea:focus{box-shadow:0 0 0 2px rgba(0,150,191,.67)}button:active,input[type=button]:active,input[type=checkbox]:active,input[type=radio]:active,input[type=submit]:active{transform:translateY(2px)}button:disabled,input:disabled,select:disabled,textarea:disabled{cursor:not-allowed;opacity:.5}::-webkit-input-placeholder{color:#a9a9a9}:-ms-input-placeholder{color:#a9a9a9}::-ms-input-placeholder{color:#a9a9a9}::placeholder{color:#a9a9a9}a{text-decoration:none;color:#41adff}a:hover{text-decoration:underline}code,kbd{background:#161f27;color:#ffbe85;padding:5px;border-radius:6px}pre>code{padding:10px;display:block;overflow-x:auto}img{max-width:100%}hr{border:none;border-top:1px solid #dbdbdb}table{border-collapse:collapse;margin-bottom:10px;width:100%}td,th{padding:6px;text-align:left}th{border-bottom:1px solid #dbdbdb}tbody tr:nth-child(2n){background-color:#161f27}::-webkit-scrollbar{height:10px;width:10px}::-webkit-scrollbar-track{background:#161f27;border-radius:6px}::-webkit-scrollbar-thumb{background:#324759;border-radius:6px}::-webkit-scrollbar-thumb:hover{background:#415c73}
+    </style>
+</head>
+<body>
+  <p>{{ message }}</p>
+  {% if attempts_left %}
+  <p>You have {{ attempts_left }} attempt(s) left</p>
+  <input type="button" value="Bo back" onclick="window.history.back()" />
+  {% elif attempts_left == 0 %}
+    <p>Captcha is now invalid (reload page after you go back)</p>
+    <input type="button" value="Bo back" onclick="window.history.back()" />
+  {% endif %}
+</body>
+</html>