bitbeans.sodium.js

/*
 * bitbeans.sodium.js 
 *
 * Copyright (c) 2015 bitbeans
 *
 * Version: 1.0.0
 *
 * Uses: 
 * https://github.com/jedisct1/libsodium.js
 * https://github.com/julien-maurel/jQuery-Storage-API
 */

var bitbeans = bitbeans || {};

bitbeans.global = new function() {
	storage=$.sessionStorage;
	// check if the browser can handle our safety standard
	this.isCompatible = function () {
		try {
			// check for sodium support
			var to_hex = sodium.to_hex
			// also check for sessionStorage
			if (typeof(sessionStorage) === 'undefined') {
				throw new Error("sessionStorage not supported");
			}
			return true;
		}
		catch(err) {
			return false;
		}
	};
}

bitbeans.security = new function() {
	// this one should be called on the login script, so the user can
	// encrypt and decrypt personal database fields locally before we store them.
	// the password_hash should come as 64 byte blake2b hash.
	this.prepareUserStorage = function (username, password_hash) {
		if ((typeof username !== "undefined") && (typeof password_hash !== "undefined")) {
			if (!storage.isSet('userdata.key')) {
				if (password_hash.length == 128) {
					// first generate a salt from the given username
					var salt = sodium.crypto_generichash(sodium.crypto_pwhash_scryptsalsa208sha256_SALTBYTES, username, 'uint8array');
					// next derive a key from the given password_hash and the salt
					var key = sodium.crypto_pwhash_scryptsalsa208sha256(sodium.from_hex(password_hash), salt, 
						sodium.crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE, 
						sodium.crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE, 32);
					// clear the salt
					sodium.memzero(salt);
					// save the key to the session storage
					storage.set('userdata.key', sodium.to_hex(key));
					// clear the key
					sodium.memzero(key);
				}
				else {
					throw new Error("password_hash seems to be of invalid length");
				}
			}
		}
		else {
			throw new Error("missing parameters");
		}
	};

	this.userEncrypt = function (userdata) {
		if (typeof userdata !== "undefined") {
			if (storage.isSet('userdata.key')) {
				// retrieve the key from the session storage
				var key = sodium.from_hex(storage.get('userdata.key'));
				// generate a random nonce
				var nonce = sodium.randombytes_buf(sodium.crypto_box_NONCEBYTES);
				var encryptedUserData = sodium.to_hex(nonce) + sodium.to_hex(sodium.crypto_secretbox_easy(userdata, nonce, key));
				sodium.memzero(key);
				sodium.memzero(nonce);
				return encryptedUserData;
			}
			else {
				throw new Error("missing userdata.key");
			}
		}
		else {
			throw new Error("missing parameters");
		}
	};

	this.userDecrypt = function (encryptedUserData) {
		if (typeof encryptedUserData !== "undefined") {
			if (storage.isSet('userdata.key')) {
				// retrieve the key from the session storage
				var key = sodium.from_hex(storage.get('userdata.key'));
				// get the nonce from the encryptedUserData
				var nonce = sodium.from_hex(encryptedUserData.substr(0, 48));
				var cipher = sodium.from_hex(encryptedUserData.substr(48));
				var decryptedUserData = sodium.crypto_secretbox_open_easy(cipher, nonce, key, 'text');
				sodium.memzero(key);
				sodium.memzero(nonce);
				sodium.memzero(cipher);
				return decryptedUserData;
			}
			else {
				throw new Error("missing userdata.key");
			}
		}
		else {
			throw new Error("missing parameters");
		}
	};
}