83 lines
2.8 KiB
JavaScript
83 lines
2.8 KiB
JavaScript
/** \file
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* \brief This file contains wrappers for the EME standard
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*
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* \see https://developer.mozilla.org/en-US/docs/Web/API/Navigator/requestMediaKeySystemAccess
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*
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* \author Copyright (C) 2022 Libor Polcak
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*
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* \license SPDX-License-Identifier: GPL-3.0-or-later
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*/
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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/** \file
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* \ingroup wrappers
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*
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* `Navigator.requestMediaKeySystemAccess()` provides access to `MediaKeySystemAccess` object that
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* allows to query supported encryption mechanisms and other information about the system.
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*
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* For example, visit https://www.fit.vutbr.cz/~polcak/jsr/hdcp/ and try a different browser or
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* computer.
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*
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* \see https://w3c.github.io/encrypted-media/
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* \see https://developer.mozilla.org/en-US/docs/Web/API/Navigator/requestMediaKeySystemAccess
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* \see https://developer.mozilla.org/en-US/docs/Web/API/MediaKeySystemAccess
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* \see https://developer.mozilla.org/en-US/docs/Web/API/MediaKeySystemAccess/getConfiguration
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*
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* We provide two modes of protection:
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*
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* 1. Strict approach prevents accessing the API.
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* 2. Farbling approach changes the output to a non-existing key system with 12.5% probability.
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*/
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/*
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* Create private namespace
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*/
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(function() {
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var helping_code = `var approach = args[0];`;
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var wrappers = [
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{
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parent_object: "Navigator.prototype",
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parent_object_property: "requestMediaKeySystemAccess",
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wrapped_objects: [{
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original_name: "Navigator.prototype.requestMediaKeySystemAccess",
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wrapped_name: "origMKSA",
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}],
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helping_code: helping_code,
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wrapping_function_args: "keySystem, queriedConfigs, ...args",
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wrapping_function_body: `
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if (approach == 2) {
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return new Promise(() => {}); // Never resolves
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}
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else if (approach == 1) {
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keySystem = "org.jshelter";
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return origMKSA.call(this, keySystem, queriedConfigs, ...args);
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}
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else {
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var eme_prng = alea(domainHash, "requestMediaKeySystemAccess", keySystem);
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var rnd = eme_prng.get_bits(3);
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if (rnd == 0) {
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keySystem = "org.jshelter";
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return origMKSA.call(this, keySystem, queriedConfigs, ...args);
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}
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else {
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return origMKSA.call(this, keySystem, queriedConfigs, ...args);
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}
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}
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`,
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},
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]
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add_wrappers(wrappers);
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})()
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