js 加密方法Encrypt

function Encrypt(str, pwd) { ???????if (str == "") return ""; ???????str = escape(str); ???????if (!pwd || pwd == "") { ???????????var pwd = "1234"; ???????} ???????pwd = escape(pwd); ???????if (pwd == null || pwd.length <= 0) { ???????????alert("Please enter a password with which to encrypt the message."); ???????????return null; ???????} ???????var prand = ""; ???????for (var I = 0; I < pwd.length; I++) { ???????????prand += pwd.charCodeAt(I).toString(); ???????} ???????var sPos = Math.floor(prand.length / 5); ???????var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos * 2) + prand.charAt(sPos * 3) + prand.charAt(sPos * 4) + prand.charAt(sPos * 5)); ???????var incr = Math.ceil(pwd.length / 2); ???????var modu = Math.pow(2, 31) - 1; ???????if (mult < 2) { ???????????alert("Algorithm cannot find a suitable hash. Please choose a different password. /n Possible considerations are to choose a more complex or longer password."); ???????????return null; ???????} ???????var salt = Math.round(Math.random() * 1000000000) % 100000000; ???????prand += salt; ???????while (prand.length > 10) { ???????????prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString(); ???????} ???????prand = (mult * prand + incr) % modu; ???????var enc_chr = ""; ???????var enc_str = ""; ???????for (var I = 0; I < str.length; I++) { ???????????enc_chr = parseInt(str.charCodeAt(I) ^ Math.floor((prand / modu) * 255)); ???????????if (enc_chr < 16) { ???????????????enc_str += "0" + enc_chr.toString(16); ???????????} else ???????????????enc_str += enc_chr.toString(16); ???????????prand = (mult * prand + incr) % modu; ???????} ???????salt = salt.toString(16); ???????while (salt.length < 8) salt = "0" + salt; ???????enc_str += salt; ???????return enc_str; ???}