Simple Angular xorcipher service

angular-xorcipher.js

// credit goes to the author of this code https://gist.github.com/sukima/5613286
// How to use it
// Inject the service in the controller and then use it as follow:

// define a encription key;
// var encryptionKey = "147";

// then you can decode and ancode with decode and encode methods
// var encodedString = xorcipher.encode(encryptionKey,"this is a string to encode")
// var decodedSting = xorcipher.decode(encryptionKey,encodedString)

factory("xorcipher",[function(){
	var b64_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

	function b64_encode(data) {
		var o1, o2, o3, h1, h2, h3, h4, bits, r, i = 0, enc = "";
		if (!data) { return data; }
		do {
		  o1 = data[i++];
		  o2 = data[i++];
		  o3 = data[i++];
		  bits = o1 << 16 | o2 << 8 | o3;
		  h1 = bits >> 18 & 0x3f;
		  h2 = bits >> 12 & 0x3f;
		  h3 = bits >> 6 & 0x3f;
		  h4 = bits & 0x3f;
		  enc += b64_table.charAt(h1) + b64_table.charAt(h2) + b64_table.charAt(h3) + b64_table.charAt(h4);
		} while (i < data.length);
		r = data.length % 3;
		return (r ? enc.slice(0, r - 3) : enc) + "===".slice(r || 3);
	}

	function b64_decode(data) {
		var o1, o2, o3, h1, h2, h3, h4, bits, i = 0, result = [];
		if (!data) { return data; }
		data += "";
		do {
		  h1 = b64_table.indexOf(data.charAt(i++));
		  h2 = b64_table.indexOf(data.charAt(i++));
		  h3 = b64_table.indexOf(data.charAt(i++));
		  h4 = b64_table.indexOf(data.charAt(i++));
		  bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;
		  o1 = bits >> 16 & 0xff;
		  o2 = bits >> 8 & 0xff;
		  o3 = bits & 0xff;
		  result.push(o1);
		  if (h3 !== 64) {
		    result.push(o2);
		    if (h4 !== 64) {
		      result.push(o3);
		    }
		  }
		} while (i < data.length);
		return result;
	}

	function keyCharAt(key, i) {
		return key.charCodeAt( Math.floor(i % key.length) );
	}

	function xor_encrypt(key, data) {
		return _.map(data, function(c, i) {
		  	return c.charCodeAt(0) ^ keyCharAt(key, i);
		});
	}

	function xor_decrypt(key, data) {
		return _.map(data, function(c, i) {
			return String.fromCharCode( c ^ keyCharAt(key, i) );
		}).join("");
	}

 	return {
		encode: function(key, data) {
		  data = xor_encrypt(key, data);
		  return b64_encode(data);
		},
		decode: function(key, data) {
		  data = b64_decode(data);
		  return xor_decrypt(key, data);
		}
    };

}]);