Add option for user to delete their account

src/invidious/helpers/helpers.cr

@@ -389,3 +389,51 @@ def extract_items(nodeset, ucid = nil)
 
   return items
 end
+
+def create_response(user_id, operation, key)
+  nonce = Random::Secure.hex(4)
+  expire = Time.now + 6.hours
+
+  challenge = "#{expire.to_unix}-#{nonce}-#{user_id}-#{operation}"
+  token = OpenSSL::HMAC.digest(:sha256, key, challenge)
+
+  challenge = Base64.urlsafe_encode(challenge)
+  token = Base64.urlsafe_encode(token)
+
+  return challenge, token
+end
+
+def validate_response(challenge, token, action, key)
+  if !challenge
+    raise "Hidden field \"challenge\" is a required field"
+  end
+
+  if !token
+    raise "Hidden field \"token\" is a required field"
+  end
+
+  challenge = Base64.decode_string(challenge)
+  if challenge.split("-").size == 4
+    expire, nonce, user_id, operation = challenge.split("-")
+
+    expire = expire.to_i?
+    expire ||= 0
+  else
+    raise "Invalid challenge"
+  end
+
+  challenge = OpenSSL::HMAC.digest(:sha256, HMAC_KEY, challenge)
+  challenge = Base64.urlsafe_encode(challenge)
+
+  if challenge != token
+    raise "Invalid token"
+  end
+
+  if operation != action
+    raise "Invalid token"
+  end
+
+  if expire < Time.now.to_unix
+    raise "Token is expired, please try again"
+  end
+end