how to encrypted schema data in PostgreSQL using update statement?

Hello, im trying to make a query that will encrypt all data in a certain schema by using update statement and by adding an encrypted random ID and im having trouble with it. Is this possible? im using md5 for encryption.. sample code is like this: update schema set column1 = md5(column),column2 = md5(cloumn2) +
(select cast(id as numeric) + cast((SELECT array_to_string(ARRAY(SELECT chr((48 + round(random() * 9)) :: integer)
FROM generate_series(1,16)), ”)) as numeric)) from schema; .. Thank you so much in advance for the help.