Remember nonce to prevent replay attacks

config/sql/nonces.sql

@@ -0,0 +1,13 @@
+-- Table: public.nonces
+
+-- DROP TABLE public.nonces;
+
+CREATE TABLE public.nonces
+(
+  nonce text
+)
+WITH (
+  OIDS=FALSE
+);
+
+GRANT ALL ON TABLE public.nonces TO kemal;

setup.sh

@@ -7,3 +7,4 @@ psql invidious < config/sql/channels.sql
 psql invidious < config/sql/videos.sql
 psql invidious < config/sql/channel_videos.sql
 psql invidious < config/sql/users.sql
+psql invidious < config/sql/nonces.sql

src/invidious.cr

@@ -142,7 +142,7 @@ before_all do |env|
       user = PG_DB.query_one?("SELECT * FROM users WHERE $1 = ANY(id)", sid, as: User)
 
       if user
-        challenge, token = create_response(user.email, "sign_out", HMAC_KEY, 1.week)
+        challenge, token = create_response(user.email, "sign_out", HMAC_KEY, PG_DB, 1.week)
 
         env.set "challenge", challenge
         env.set "token", token
@@ -155,7 +155,7 @@ before_all do |env|
         client = make_client(YT_URL)
         user = get_user(sid, client, headers, PG_DB, false)
 
-        challenge, token = create_response(user.email, "sign_out", HMAC_KEY, 1.week)
+        challenge, token = create_response(user.email, "sign_out", HMAC_KEY, PG_DB, 1.week)
         env.set "challenge", challenge
         env.set "token", token
 
@@ -624,7 +624,7 @@ get "/login" do |env|
   account_type ||= "invidious"
 
   if account_type == "invidious"
-    captcha = generate_captcha(HMAC_KEY)
+    captcha = generate_captcha(HMAC_KEY, PG_DB)
   end
 
   tfa = env.params.query["tfa"]?
@@ -815,9 +815,26 @@ post "/login" do |env|
       next templated "error"
     end
   elsif account_type == "invidious"
-    challenge_response = env.params.body["challenge_response"]?
+    answer = env.params.body["answer"]?
+
+    if !answer
+      error_message = "CAPTCHA is a required field"
+      next templated "error"
+    end
+
+    answer = answer.lstrip('0')
+    answer = OpenSSL::HMAC.hexdigest(:sha256, HMAC_KEY, answer)
+
+    challenge = env.params.body["challenge"]?
     token = env.params.body["token"]?
 
+    begin
+      validate_response(challenge, token, answer, "sign_in", HMAC_KEY, PG_DB)
+    rescue ex
+      error_message = ex.message
+      next templated "error"
+    end
+
     action = env.params.body["action"]?
     action ||= "signin"
 
@@ -831,18 +848,6 @@ post "/login" do |env|
       next templated "error"
     end
 
-    if !challenge_response || !token
-      error_message = "CAPTCHA is a required field"
-      next templated "error"
-    end
-
-    challenge_response = challenge_response.lstrip('0')
-    if OpenSSL::HMAC.digest(:sha256, HMAC_KEY, challenge_response) == Base64.decode(token)
-    else
-      error_message = "Invalid CAPTCHA response"
-      next templated "error"
-    end
-
     if action == "signin"
       user = PG_DB.query_one?("SELECT * FROM users WHERE LOWER(email) = LOWER($1) AND password IS NOT NULL", email, as: User)
 
@@ -940,7 +945,7 @@ get "/signout" do |env|
     token = env.params.query["token"]?
 
     begin
-      validate_response(challenge, token, user.email, "sign_out", HMAC_KEY)
+      validate_response(challenge, token, user.email, "sign_out", HMAC_KEY, PG_DB)
     rescue ex
       error_message = ex.message
       next templated "error"
@@ -1461,7 +1466,7 @@ get "/delete_account" do |env|
   if user
     user = user.as(User)
 
-    challenge, token = create_response(user.email, "delete_account", HMAC_KEY)
+    challenge, token = create_response(user.email, "delete_account", HMAC_KEY, PG_DB)
 
     templated "delete_account"
   else
@@ -1480,7 +1485,7 @@ post "/delete_account" do |env|
     token = env.params.body["token"]?
 
     begin
-      validate_response(challenge, token, user.email, "delete_account", HMAC_KEY)
+      validate_response(challenge, token, user.email, "delete_account", HMAC_KEY, PG_DB)
     rescue ex
       error_message = ex.message
       next templated "error"
@@ -1506,7 +1511,7 @@ get "/clear_watch_history" do |env|
   if user
     user = user.as(User)
 
-    challenge, token = create_response(user.email, "clear_watch_history", HMAC_KEY)
+    challenge, token = create_response(user.email, "clear_watch_history", HMAC_KEY, PG_DB)
 
     templated "clear_watch_history"
   else
@@ -1525,7 +1530,7 @@ post "/clear_watch_history" do |env|
     token = env.params.body["token"]?
 
     begin
-      validate_response(challenge, token, user.email, "clear_watch_history", HMAC_KEY)
+      validate_response(challenge, token, user.email, "clear_watch_history", HMAC_KEY, PG_DB)
     rescue ex
       error_message = ex.message
       next templated "error"

src/invidious/helpers/helpers.cr

@@ -130,55 +130,6 @@ def login_req(login_form, f_req)
   return HTTP::Params.encode(data)
 end
 
-def generate_captcha(key)
-  minute = Random::Secure.rand(12)
-  minute_angle = minute * 30
-  minute = minute * 5
-
-  hour = Random::Secure.rand(12)
-  hour_angle = hour * 30 + minute_angle.to_f / 12
-  if hour == 0
-    hour = 12
-  end
-
-  clock_svg = <<-END_SVG
-  <svg viewBox="0 0 100 100" width="200px">
-  <circle cx="50" cy="50" r="45" fill="#eee" stroke="black" stroke-width="2"></circle>
-  
-  <text x="69"     y="20.091" text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 1</text>
-  <text x="82.909" y="34"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 2</text>
-  <text x="88"     y="53"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 3</text>
-  <text x="82.909" y="72"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 4</text>
-  <text x="69"     y="85.909" text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 5</text>
-  <text x="50"     y="91"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 6</text>
-  <text x="31"     y="85.909" text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 7</text>
-  <text x="17.091" y="72"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 8</text>
-  <text x="12"     y="53"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 9</text>
-  <text x="17.091" y="34"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px">10</text>
-  <text x="31"     y="20.091" text-anchor="middle" fill="black" font-family="Arial" font-size="10px">11</text>
-  <text x="50"     y="15"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px">12</text>
-
-  <circle cx="50" cy="50" r="3" fill="black"></circle>
-  <line id="minute" transform="rotate(#{minute_angle}, 50, 50)" x1="50" y1="50" x2="50" y2="16" fill="black" stroke="black" stroke-width="2"></line>
-  <line id="hour"   transform="rotate(#{hour_angle}, 50, 50)" x1="50" y1="50" x2="50" y2="24" fill="black" stroke="black" stroke-width="2"></line>
-  </svg>
-  END_SVG
-
-  challenge = ""
-  convert = Process.run(%(convert -density 1200 -resize 400x400 -background none svg:- png:-), shell: true,
-    input: IO::Memory.new(clock_svg), output: Process::Redirect::Pipe) do |proc|
-    challenge = proc.output.gets_to_end
-    challenge = Base64.strict_encode(challenge)
-    challenge = "data:image/png;base64,#{challenge}"
-  end
-
-  answer = "#{hour}:#{minute.to_s.rjust(2, '0')}"
-  token = OpenSSL::HMAC.digest(:sha256, key, answer)
-  token = Base64.urlsafe_encode(token)
-
-  return {challenge: challenge, token: token}
-end
-
 def html_to_content(description_html)
   if !description_html
     description = ""

src/invidious/users.cr

@@ -200,9 +200,10 @@ def create_user(sid, email, password)
   return user
 end
 
-def create_response(user_id, operation, key, expire = 6.hours)
+def create_response(user_id, operation, key, db, expire = 6.hours)
   expire = Time.now + expire
-  nonce = Random::Secure.hex(4)
+  nonce = Random::Secure.hex(16)
+  db.exec("INSERT INTO nonces VALUES ($1) ON CONFLICT DO NOTHING", nonce)
 
   challenge = "#{expire.to_unix}-#{nonce}-#{user_id}-#{operation}"
   token = OpenSSL::HMAC.digest(:sha256, key, challenge)
@@ -213,7 +214,7 @@ def create_response(user_id, operation, key, expire = 6.hours)
   return challenge, token
 end
 
-def validate_response(challenge, token, user_id, operation, key)
+def validate_response(challenge, token, user_id, operation, key, db)
   if !challenge
     raise "Hidden field \"challenge\" is a required field"
   end
@@ -235,6 +236,12 @@ def validate_response(challenge, token, user_id, operation, key)
   challenge = OpenSSL::HMAC.digest(:sha256, HMAC_KEY, challenge)
   challenge = Base64.urlsafe_encode(challenge)
 
+  if db.query_one?("SELECT EXISTS (SELECT true FROM nonces WHERE nonce = $1)", nonce, as: Bool)
+    db.exec("DELETE FROM nonces * WHERE nonce = $1", nonce)
+  else
+    raise "Invalid token"
+  end
+
   if challenge != token
     raise "Invalid token"
   end
@@ -251,3 +258,53 @@ def validate_response(challenge, token, user_id, operation, key)
     raise "Token is expired, please try again"
   end
 end
+
+def generate_captcha(key, db)
+  minute = Random::Secure.rand(12)
+  minute_angle = minute * 30
+  minute = minute * 5
+
+  hour = Random::Secure.rand(12)
+  hour_angle = hour * 30 + minute_angle.to_f / 12
+  if hour == 0
+    hour = 12
+  end
+
+  clock_svg = <<-END_SVG
+  <svg viewBox="0 0 100 100" width="200px">
+  <circle cx="50" cy="50" r="45" fill="#eee" stroke="black" stroke-width="2"></circle>
+  
+  <text x="69"     y="20.091" text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 1</text>
+  <text x="82.909" y="34"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 2</text>
+  <text x="88"     y="53"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 3</text>
+  <text x="82.909" y="72"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 4</text>
+  <text x="69"     y="85.909" text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 5</text>
+  <text x="50"     y="91"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 6</text>
+  <text x="31"     y="85.909" text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 7</text>
+  <text x="17.091" y="72"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 8</text>
+  <text x="12"     y="53"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px"> 9</text>
+  <text x="17.091" y="34"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px">10</text>
+  <text x="31"     y="20.091" text-anchor="middle" fill="black" font-family="Arial" font-size="10px">11</text>
+  <text x="50"     y="15"     text-anchor="middle" fill="black" font-family="Arial" font-size="10px">12</text>
+
+  <circle cx="50" cy="50" r="3" fill="black"></circle>
+  <line id="minute" transform="rotate(#{minute_angle}, 50, 50)" x1="50" y1="50" x2="50" y2="16" fill="black" stroke="black" stroke-width="2"></line>
+  <line id="hour"   transform="rotate(#{hour_angle}, 50, 50)" x1="50" y1="50" x2="50" y2="24" fill="black" stroke="black" stroke-width="2"></line>
+  </svg>
+  END_SVG
+
+  image = ""
+  convert = Process.run(%(convert -density 1200 -resize 400x400 -background none svg:- png:-), shell: true,
+    input: IO::Memory.new(clock_svg), output: Process::Redirect::Pipe) do |proc|
+    image = proc.output.gets_to_end
+    image = Base64.strict_encode(image)
+    image = "data:image/png;base64,#{image}"
+  end
+
+  answer = "#{hour}:#{minute.to_s.rjust(2, '0')}"
+  answer = OpenSSL::HMAC.hexdigest(:sha256, key, answer)
+
+  challenge, token = create_response(answer, "sign_in", key, db)
+
+  return {image: image, challenge: challenge, token: token}
+end

src/invidious/views/login.ecr

@@ -24,10 +24,11 @@
                     <label for="password">Password:</label>
                     <input required class="pure-input-1" name="password" type="password" placeholder="Password">
                 
-                    <img style="width:100%" src='<%= captcha.not_nil![:challenge] %>'/>
+                    <img style="width:100%" src='<%= captcha.not_nil![:image] %>'/>
                     <input type="hidden" name="token" value="<%= captcha.not_nil![:token] %>">
-                    <label for="challenge_response">Time (h:mm):</label>
+                    <input type="hidden" name="challenge" value="<%= captcha.not_nil![:challenge] %>">
-                    <input required type="text" name="challenge_response" type="text>" placeholder="hh:mm">
+                    <label for="answer">Time (h:mm):</label>
+                    <input required type="text" name="answer" type="text>" placeholder="hh:mm">
 
                     <button type="submit" name="action" value="signin" class="pure-button pure-button-primary">Sign In</button>
                     <button type="submit" name="action" value="register" class="pure-button pure-button-primary">Register</button>