Find the name of the current password function
SELECT * FROM DBA_PROFILES WHERE RESOURCE_NAME='PASSWORD_VERIFY_FUNCTION';
Change the password function for the profile:
ALTER PROFILE &profile. LIMIT PASSWORD_VERIFY_FUNCTION &function_name.;
Example of the password function:
CREATE OR REPLACE FUNCTION dummy_func
(USERNAME VARCHAR2, PASSWORD VARCHAR2, OLD_PASSWORD VARCHAR2)
RETURN BOOLEAN IS
BEGIN
IF NLS_LOWER(password) = NLS_LOWER(username) THEN
raise_application_error(-20001, 'Password is the same as the username');
END IF;
RETURN(TRUE);
END;