How to encrypt data in Postgresql

Hi there:

 

I know this might be an easy answer, but I was unable to figure out the solution.

 

I would like to encrypt a password field in the table. I could not figure out how phpPGAdmin did.

 

Should I use PHP's MD5 to encrypt the password? Is there a function in PostgreSQL that can encrypt the data with MD5?

 

I would like to encrypt the data in PostgreSQL, so other program can use the same function. Can anyone give me some hints? What key word should I search in the document?

 

Thansk!