Hi,

GlideEncrypter is used to store sensitive information like passwords. It should definitely work with those characters. 

I have tested your problem with the following and got the correct result:

var encrypter = new GlideEncrypter(); 
var clearString = '"/*ab*cd*efg/'; 
var encrString = encrypter.encrypt(clearString);
var decrString = encrypter.decrypt(encrString); 
gs.print("Encrypted string = " + encrString); 
gs.print("Decrypted string = " + decrString);