create extension pgcrypto;

encrypt(data bytea, key bytea, type text) --加密
decrypt(data bytea, key bytea, type text) --解密

select encrypt('postgres','abc','aes');

select convert_from(decrypt('\xd664687424b2806001d0744177284420','abc','aes'),'SQL_ASCII');

test=# create table user_test(username varchar(20),password varchar(60));
CREATE TABLE
test=# insert into user_test values('miya',encode(encrypt('123','abc','aes'),'hex'));
INSERT 0 1
test=# insert into user_test values('kimi',encode(encrypt('456','abc','aes'),'hex'));
INSERT 0 1
test=# select * from user_test;
 username |    password    
----------+----------------------------------
 miya  | a4bf9afce727dbd2805393a86a24096c
 kimi  | 84279efc7942ca7364abcce78db90b0b
(2 rows)

test=# select convert_from(decrypt(decode(password,'hex'),'abc','aes'),'SQL_ASCII') as real_pw,* from user_test;
 real_pw | username |    password    
---------+----------+----------------------------------
 123  | miya  | a4bf9afce727dbd2805393a86a24096c
 456  | kimi  | 84279efc7942ca7364abcce78db90b0b

make USE_PGXS=1
make install

create extension pgcrypto ;

select encrypt('123456','aa','aes');
    encrypt    
------------------------------------
 \x39c3c665757a0ff973b83fb98cc3d63f

select convert_from(decrypt('\x39c3c665757a0ff973b83fb98cc3d63f','aa','aes'),'SQL_ASCII');
 convert_from 
--------------
 123456