114 rader
4,5 KiB
JavaScript
114 rader
4,5 KiB
JavaScript
/*
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* vim: ts=4:sw=4:expandtab
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*/
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;(function(){
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'use strict';
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var encrypt = libsignal.crypto.encrypt;
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var decrypt = libsignal.crypto.decrypt;
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var calculateMAC = libsignal.crypto.calculateMAC;
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var verifyMAC = libsignal.crypto.verifyMAC;
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function verifyDigest(data, theirDigest) {
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return crypto.subtle.digest({name: 'SHA-256'}, data).then(function(ourDigest) {
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var a = new Uint8Array(ourDigest);
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var b = new Uint8Array(theirDigest);
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var result = 0;
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for (var i=0; i < theirDigest.byteLength; ++i) {
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result = result | (a[i] ^ b[i]);
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}
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if (result !== 0) {
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throw new Error('Bad digest');
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}
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});
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}
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function calculateDigest(data) {
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return crypto.subtle.digest({name: 'SHA-256'}, data);
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}
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window.textsecure = window.textsecure || {};
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window.textsecure.crypto = {
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// Decrypts message into a raw string
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decryptWebsocketMessage: function(message, signaling_key) {
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var decodedMessage = message.toArrayBuffer();
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if (signaling_key.byteLength != 52) {
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throw new Error("Got invalid length signaling_key");
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}
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if (decodedMessage.byteLength < 1 + 16 + 10) {
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throw new Error("Got invalid length message");
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}
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if (new Uint8Array(decodedMessage)[0] != 1) {
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throw new Error("Got bad version number: " + decodedMessage[0]);
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}
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var aes_key = signaling_key.slice(0, 32);
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var mac_key = signaling_key.slice(32, 32 + 20);
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var iv = decodedMessage.slice(1, 1 + 16);
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var ciphertext = decodedMessage.slice(1 + 16, decodedMessage.byteLength - 10);
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var ivAndCiphertext = decodedMessage.slice(0, decodedMessage.byteLength - 10);
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var mac = decodedMessage.slice(decodedMessage.byteLength - 10, decodedMessage.byteLength);
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return verifyMAC(ivAndCiphertext, mac_key, mac, 10).then(function() {
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return decrypt(aes_key, ciphertext, iv);
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});
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},
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decryptAttachment: function(encryptedBin, keys, theirDigest) {
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if (keys.byteLength != 64) {
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throw new Error("Got invalid length attachment keys");
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}
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if (encryptedBin.byteLength < 16 + 32) {
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throw new Error("Got invalid length attachment");
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}
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var aes_key = keys.slice(0, 32);
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var mac_key = keys.slice(32, 64);
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var iv = encryptedBin.slice(0, 16);
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var ciphertext = encryptedBin.slice(16, encryptedBin.byteLength - 32);
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var ivAndCiphertext = encryptedBin.slice(0, encryptedBin.byteLength - 32);
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var mac = encryptedBin.slice(encryptedBin.byteLength - 32, encryptedBin.byteLength);
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return verifyMAC(ivAndCiphertext, mac_key, mac, 32).then(function() {
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if (theirDigest !== undefined) {
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return verifyDigest(encryptedBin, theirDigest);
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}
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}).then(function() {
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return decrypt(aes_key, ciphertext, iv);
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});
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},
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encryptAttachment: function(plaintext, keys, iv) {
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if (keys.byteLength != 64) {
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throw new Error("Got invalid length attachment keys");
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}
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if (iv.byteLength != 16) {
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throw new Error("Got invalid length attachment iv");
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}
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var aes_key = keys.slice(0, 32);
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var mac_key = keys.slice(32, 64);
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return encrypt(aes_key, plaintext, iv).then(function(ciphertext) {
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var ivAndCiphertext = new Uint8Array(16 + ciphertext.byteLength);
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ivAndCiphertext.set(new Uint8Array(iv));
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ivAndCiphertext.set(new Uint8Array(ciphertext), 16);
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return calculateMAC(mac_key, ivAndCiphertext.buffer).then(function(mac) {
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var encryptedBin = new Uint8Array(16 + ciphertext.byteLength + 32);
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encryptedBin.set(ivAndCiphertext);
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encryptedBin.set(new Uint8Array(mac), 16 + ciphertext.byteLength);
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return calculateDigest(encryptedBin.buffer).then(function(digest) {
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return { ciphertext: encryptedBin.buffer, digest: digest };
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});
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});
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});
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},
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getRandomBytes: function(size) {
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return libsignal.crypto.getRandomBytes(size);
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}
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};
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})();
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