title: Postgres 11.4 crypt extension issue in postgres
body: <p>i am using pgcrypto extension for password encryption in my PostgreSQL db. i am using same key to encrypt all passwords. When i use same key in different passwords(different strings) it gives same output.</p>
  
  <p><strong>Samples:</strong></p>
  
  <pre><code>db=# select crypt('Sharon_1','alpha');
       crypt     
  ---------------
   aljp4LCkDT1k.
  (1 row)
  
  Time: 2.025 ms
  db=# select crypt('Sharon_1trgstysa','alpha');
       crypt     
  ---------------
   aljp4LCkDT1k.
  (1 row)
  </code></pre>
  
  <p>why is it like that?. When i pass two different strings it should give different encrypted strings as output.Is this a bug?. How can i solve this ? i can't change the key. The key should be always same.</p>
  
  <p><strong>Postgres version:</strong></p>
  
  <pre><code>db=# select version();
  
   PostgreSQL 11.4 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28),
   64-bit
  </code></pre>
  
  <p><strong>Extension version:</strong></p>
  
  <pre><code>db=# \dx pgcrypto
  
               List of installed extensions
     Name   | Version | Schema |       Description       
  ----------+---------+--------+-------------------------
  
   pgcrypto | 1.3     | public    | cryptographic functions
  </code></pre>