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Diffstat (limited to 'common/signing.js')
-rw-r--r-- | common/signing.js | 108 |
1 files changed, 0 insertions, 108 deletions
diff --git a/common/signing.js b/common/signing.js deleted file mode 100644 index db2aa92..0000000 --- a/common/signing.js +++ /dev/null @@ -1,108 +0,0 @@ -/** - * This file is part of Haketilo. - * - * Functions: Operations related to "signing" of data. - * - * Copyright (C) 2021 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 this code in a - * proprietary program, I am not going to enforce this in court. - */ - -/* - * IMPORTS_START - * IMPORT sha256 - * IMPORT browser - * IMPORT is_mozilla - * IMPORTS_END - */ - -/* - * In order to make certain data synchronously accessible in certain contexts, - * Haketilo smuggles it in string form in places like cookies, URLs and headers. - * When using the smuggled data, we first need to make sure it isn't spoofed. - * For that, we use this pseudo-signing mechanism. - * - * Despite what name suggests, no assymetric cryptography is involved, as it - * would bring no additional benefits and would incur bigger performance - * overhead. Instead, we hash the string data together with some secret value - * that is supposed to be known only by this browser instance. Resulting hash - * sum plays the role of the signature. In the hash we also include current - * time. This way, even if signed data leaks (which shouldn't happen in the - * first place), an attacker won't be able to re-use it indefinitely. - * - * The secret shared between execution contexts has to be available - * synchronously. Under Mozilla, this is the extension's per-session id. Under - * Chromium, this is a dummy web-accessible-resource name that resides in the - * manifest and is supposed to be constructed by each user using a unique value - * (this is done automatically by `build.sh'). - */ - -function get_secret() -{ - if (is_mozilla) - return browser.runtime.getURL("dummy"); - - return chrome.runtime.getManifest().web_accessible_resources - .map(r => /^chromium-key-dummy-file-(.*)/.exec(r)).filter(r => r)[0][1]; -} - -function extract_signed(signature, signed_data) -{ - const match = /^([1-9][0-9]{12}|0)_(.*)$/.exec(signed_data); - if (!match) - return {fail: "bad format"}; - - const result = {time: parseInt(match[1]), data: match[2]}; - if (sign_data(result.data, result.time)[0] !== signature) - result.fail = "bad signature"; - - return result; -} - -/* - * Sign a given string for a given time. Time should be either 0 or in the range - * 10^12 <= time < 10^13. - */ -function sign_data(data, time) { - return [sha256(get_secret() + time + data), `${time}_${data}`]; -} - -/* - * EXPORTS_START - * EXPORT extract_signed - * EXPORT sign_data - * EXPORTS_END - */ |