totp code management and countdown timer

src/services/totpService.js

@@ -0,0 +1,93 @@
+function TotpService() {
+    initTotpService();
+};
+
+function initTotpService() {
+    var b32Chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
+
+    var leftpad = function (s, l, p) {
+        if (l + 1 >= s.length) {
+            s = Array(l + 1 - s.length).join(p) + s;
+        }
+        return s;
+    };
+
+    var dec2hex = function (d) {
+        return (d < 15.5 ? '0' : '') + Math.round(d).toString(16);
+    };
+
+    var hex2dec = function (s) {
+        return parseInt(s, 16);
+    };
+
+    var hex2bytes = function (s) {
+        var bytes = new Uint8Array(s.length / 2);
+        for (var i = 0; i < s.length; i += 2) {
+            bytes[i / 2] = parseInt(s.substr(i, 2), 16);
+        }
+        return bytes;
+    }
+
+    var buff2hex = function (buff) {
+        var bytes = new Uint8Array(buff);
+        var hex = [];
+        for (var i = 0; i < bytes.length; i++) {
+            hex.push((bytes[i] >>> 4).toString(16));
+            hex.push((bytes[i] & 0xF).toString(16));
+        }
+        return hex.join('');
+    }
+
+    var b32tohex = function (s) {
+        var bits = '';
+        var hex = '';
+        for (var i = 0; i < s.length; i++) {
+            var val = b32Chars.indexOf(s.charAt(i).toUpperCase());
+            bits += leftpad(val.toString(2), 5, '0');
+        }
+        for (var i = 0; i + 4 <= bits.length; i += 4) {
+            var chunk = bits.substr(i, 4);
+            hex = hex + parseInt(chunk, 2).toString(16);
+        }
+        return hex;
+    };
+
+    var b32tobytes = function (s) {
+        return hex2bytes(b32tohex(s));
+    };
+
+    var sign = function (keyBytes, timeBytes) {
+        return window.crypto.subtle.importKey('raw', keyBytes,
+            { name: 'HMAC', hash: { name: 'SHA-1' } }, false, ['sign']).then(function (key) {
+                return window.crypto.subtle.sign({ name: 'HMAC', hash: { name: 'SHA-1' } }, key, timeBytes);
+            }).then(function (signature) {
+                return buff2hex(signature);
+            }).catch(function (err) {
+                return null;
+            });
+    };
+
+    TotpService.prototype.getCode = function (keyb32) {
+        var epoch = Math.round(new Date().getTime() / 1000.0);
+        var timeHex = leftpad(dec2hex(Math.floor(epoch / 30)), 16, '0');
+        var timeBytes = hex2bytes(timeHex);
+        var keyBytes = b32tobytes(keyb32);
+
+        if (!keyBytes.length || !timeBytes.length) {
+            return Q.fcall(function () {
+                return null;
+            });
+        }
+
+        return sign(keyBytes, timeBytes).then(function (hashHex) {
+            if (!hashHex) {
+                return null;
+            }
+
+            var offset = hex2dec(hashHex.substring(hashHex.length - 1));
+            var otp = (hex2dec(hashHex.substr(offset * 2, 8)) & hex2dec('7fffffff')) + '';
+            otp = (otp).substr(otp.length - 6, 6);
+            return otp;
+        });
+    };
+};