webcrypto example

crypto.js

var local;
local = {};
        local.cryptoAesDecrypt = function (key, data, onError) {
        /*
         * this function will aes-256-cbc decrypt Uint8Array data with the Uint8Array key
         * example usage:
            key = new Uint8Array(32);
            local.cryptoAesEncrypt(key, new Uint8Array([1,2,3]), function (error, data) {
                console.assert(!error, error);
                local.cryptoAesDecrypt(key, data, console.log);
            });
         */
            /*globals Uint8Array*/
            var cipher, crypto, iv;
            // init iv
            iv = data.subarray(0, 16);
            // optimization - create resized-view of data
            data = data.subarray(16);
            crypto = typeof window === 'object' && window.crypto;
            if (!(crypto && crypto.subtle && typeof crypto.subtle.importKey === 'function')) {
                setTimeout(function () {
                    crypto = require('crypto');
                    cipher = crypto.createDecipheriv('aes-256-cbc', key, iv);
                    onError(null, Buffer.concat([cipher.update(data), cipher.final()]));
                });
                return;
            }
            crypto.subtle.importKey('raw', key, {
                name: 'AES-CBC'
            }, false, ['decrypt']).then(function (key) {
                crypto.subtle.decrypt({ iv: iv, name: 'AES-CBC' }, key, data).then(function (data) {
                    onError(null, new Uint8Array(data));
                }).catch(onError);
            }).catch(onError);
        };

        local.cryptoAesEncrypt = function (key, data, onError) {
        /*
         * this function will aes-256-cbc encrypt Uint8Array data with the Uint8Array key
            key = new Uint8Array(32);
            local.cryptoAesEncrypt(key, new Uint8Array([1,2,3]), function (error, data) {
                console.assert(!error, error);
                local.cryptoAesDecrypt(key, data, console.log);
            });
         */
            /*globals Uint8Array*/
            var cipher, crypto, iv;
            // init iv
            iv = new Uint8Array(16 + Math.ceil(data.length / 16) * 16);
            crypto = typeof window === 'object' && window.crypto;
            if (!(crypto && crypto.subtle && typeof crypto.subtle.importKey === 'function')) {
                setTimeout(function () {
                    crypto = require('crypto');
                    // init iv
                    iv.set(crypto.randomBytes(16));
                    cipher = crypto.createCipheriv('aes-256-cbc', key, iv.subarray(0, 16));
                    data = cipher.update(data);
                    iv.set(data, 16);
                    iv.set(cipher.final(), 16 + data.length);
                    onError(null, iv);
                });
                return;
            }
            // init iv
            iv.set(crypto.getRandomValues(new Uint8Array(16)));
            crypto.subtle.importKey('raw', key, {
                name: 'AES-CBC'
            }, false, ['encrypt']).then(function (key) {
                crypto.subtle.encrypt({
                    iv: iv.subarray(0, 16),
                    name: 'AES-CBC'
                }, key, data).then(function (data) {
                    iv.set(new Uint8Array(data), 16);
                    onError(null, iv);
                }).catch(onError);
            }).catch(onError);
        };