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/** \file
* \brief This file contains wrappers for the EME standard
*
* \see https://developer.mozilla.org/en-US/docs/Web/API/Navigator/requestMediaKeySystemAccess
*
* \author Copyright (C) 2022 Libor Polcak
*
* \license SPDX-License-Identifier: GPL-3.0-or-later
*/
//
// 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.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
/** \file
* \ingroup wrappers
*
* `Navigator.requestMediaKeySystemAccess()` provides access to `MediaKeySystemAccess` object that
* allows to query supported encryption mechanisms and other information about the system.
*
* For example, visit https://www.fit.vutbr.cz/~polcak/jsr/hdcp/ and try a different browser or
* computer.
*
* \see https://w3c.github.io/encrypted-media/
* \see https://developer.mozilla.org/en-US/docs/Web/API/Navigator/requestMediaKeySystemAccess
* \see https://developer.mozilla.org/en-US/docs/Web/API/MediaKeySystemAccess
* \see https://developer.mozilla.org/en-US/docs/Web/API/MediaKeySystemAccess/getConfiguration
*
* We provide two modes of protection:
*
* 1. Strict approach prevents accessing the API.
* 2. Farbling approach changes the output to a non-existing key system with 12.5% probability.
*/
/*
* Create private namespace
*/
(function() {
var helping_code = `var approach = args[0];`;
var wrappers = [
{
parent_object: "Navigator.prototype",
parent_object_property: "requestMediaKeySystemAccess",
wrapped_objects: [{
original_name: "Navigator.prototype.requestMediaKeySystemAccess",
wrapped_name: "origMKSA",
}],
helping_code: helping_code,
wrapping_function_args: "keySystem, queriedConfigs, ...args",
wrapping_function_body: `
if (approach == 2) {
return new Promise(() => {}); // Never resolves
}
else if (approach == 1) {
keySystem = "org.jshelter";
return origMKSA.call(this, keySystem, queriedConfigs, ...args);
}
else {
var eme_prng = alea(domainHash, "requestMediaKeySystemAccess", keySystem);
var rnd = eme_prng.get_bits(3);
if (rnd == 0) {
keySystem = "org.jshelter";
return origMKSA.call(this, keySystem, queriedConfigs, ...args);
}
else {
return origMKSA.call(this, keySystem, queriedConfigs, ...args);
}
}
`,
},
]
add_wrappers(wrappers);
})()
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