Member Role Config

Wanted to know the correct way to set up the membership setting so user could retrive the password.

     hashAlgorithmType="SHA1"
     passwordFormat="Hashed"

I know if Have it on Hashed, it will send the user Hashed vaule instead of the user password. How would I be able to set the settign where it will return the correct value?
*Alright I figure it out using the values....

     hashAlgorithmType="Triple-DES"
     passwordFormat="Encrypted"

Now I don't get any errors regarding the enablePasswordRetrieval="true". But I do get an error trying to make a user. Do you have to assign a encryption Key? If so how and what are the tags?
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