And from a security point of view, it is a very BAD idea to store passwords. Ever. If someone asks you to do that, explain to them it is not an option.
Yes, I know that it is very bad thingy to implement.
However, the reason why I need to implement this thingy is that I am making integrate login system that enables to login to 5 different systems with different password, but, user id is the same.
Also, this has to be implemented by one clicking.
Therefore, I need to decrypt password or store the password in the database, which is bad idea.
If you need to store it. use the Crypt class to encrypt / decrypt it. That at least would require access to both your database data and your code to be able to decrypt it (as the keys are in the crypt config file).
If you're using Orm, 1.9/dev has the option to automatically encrypt/decrypt column values.