tkDerm automatically decrypt the data when it shows them. Therefore, to confirm that they are really encrypted, you should use a PostgreSQL client program called psql as follows (t1 is the database of which you are going to check the encryption).
$ psql t1
Password:
Welcome to psql 8.?.?, the PostgreSQL interactive terminal.
Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit
t1=> select id from patient;
id
------------------------------------------------
\033\231qD\261\177\347~\014{\245\035;\316y\016
(1 row)
t1=> select first_name from patient;
first_name
-------------------------
Mn\320\372\377\017\340.
(1 row)
t1=> select last_name from patient;
last_name
----------------------------
\366m?\222\310\306\232\254
(1 row)
Instead of executing these commands separately, you can type the following command.
t1=> select id,first_name,last_name from patient;