94 lines
3.8 KiB
JavaScript
94 lines
3.8 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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// Various wrappers around low-level crypto operation for specific functions
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var encrypt = function(key, data, iv) {
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return window.crypto.subtle.importKey('raw', key, {name: 'AES-CBC'}, false, ['encrypt']).then(function(key) {
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return window.crypto.subtle.encrypt({name: 'AES-CBC', iv: new Uint8Array(iv)}, key, data);
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});
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};
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var decrypt = function(key, data, iv) {
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return window.crypto.subtle.importKey('raw', key, {name: 'AES-CBC'}, false, ['decrypt']).then(function(key) {
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return window.crypto.subtle.decrypt({name: 'AES-CBC', iv: new Uint8Array(iv)}, key, data);
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});
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};
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var calculateMAC = function(key, data) {
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return window.crypto.subtle.importKey('raw', key, {name: 'HMAC', hash: {name: 'SHA-256'}}, false, ['sign']).then(function(key) {
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return window.crypto.subtle.sign( {name: 'HMAC', hash: 'SHA-256'}, key, data);
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});
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};
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var verifyMAC = function(data, key, mac) {
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return calculateMAC(key, data).then(function(calculated_mac) {
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if (!isEqual(calculated_mac, mac, true))
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throw new Error("Bad MAC");
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});
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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 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 decodedMessage = message.toArrayBuffer();
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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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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).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) {
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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).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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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 encryptedBin.buffer;
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});
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});
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},
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getRandomBytes: function(size) {
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var array = new Uint8Array(size);
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window.crypto.getRandomValues(array);
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return array.buffer;
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}
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};
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})();
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