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diff --git a/captcha-child-anchor.js b/captcha-child-anchor.js
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+/* SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * Part of Hacktcha, a free/libre front-end for reCAPTCHA for use with Haketilo.
+ *
+ * Copyright (C) 2022 Wojtek Kosior
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * As additional permission under GNU GPL version 3 section 7, you
+ * may distribute forms of that code without the copy of the GNU
+ * GPL normally required by section 4, provided you include this
+ * license notice and, in case of non-source distribution, a URL
+ * through which recipients can access the Corresponding Source.
+ * If you modify file(s) with this exception, you may extend this
+ * exception to your version of the file(s), but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * As a special exception to the GPL, any HTML file which merely
+ * makes function calls to this code, and for that purpose
+ * includes it by reference shall be deemed a separate work for
+ * copyright law purposes. If you modify this code, you may extend
+ * this exception to your version of the code, but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *
+ * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+ * license. Although I request that you do not make use of this code in a
+ * proprietary program, I am not going to enforce this in court.
+ */
+
+/* Use with https://google.com/recaptcha/api2/anchor */
+
+"use strict";
+
+/*
+ * reCAPTCHA uses a less common variant of base64 which we produce by slightly
+ * modifying the output of JavaScript's native base64 encoding routine.
+ */
+function rc_base64_decode(data_b64) {
+    data_b64 = data_b64
+	  .replaceAll("-", "+")
+	  .replaceAll("_", "/")
+	  .replaceAll(".", "=");
+
+    return atob(data_b64);
+}
+
+const rc_params = new URLSearchParams(window.location.search);
+
+const site_key   = rc_params.get("k");
+const rc_version = rc_params.get("v");
+const lang       = rc_params.get("hl") || "en";
+
+const origin_b64 = rc_params.get("co");
+const origin     = rc_base64_decode(origin_b64);
+
+const initial_token = document.getElementById("recaptcha-token").value;
+
+const smuggled_data = {origin, initial_token};
+
+const bframe_url = new URL("https://google.com/recaptcha/api2/bframe");
+bframe_url.search = new URLSearchParams([
+    ["hl", lang],
+    ["v", rc_version],
+    ["k", site_key]
+]);
+bframe_url.hash = encodeURIComponent(JSON.stringify(smuggled_data));
+
+window.location.href = bframe_url;