To change the syb_syscommkey, create a new key and use sp_hidetext to reencrypt with the new key.
For example:
Example 1 – Create a new hidden text encryption key and encrypt all SQL text objects in the syscomments table with the newly created key:
create encryption key syb_syscommkey go sp_hidetext go
When a new syb_syscommkey is created, it becomes the default key used by sp_hidetext in that database.
Example 2 – Create a new hidden text encryption key, encrypt the text of a specific stored procedure in syscomments with the newly created key, and protect the key with the master key:
create encryption key syb_syscommkey with master_key go sp_hidetext sp_mysproc go
In this example, all other hidden text rows in syscomments remain encrypted with the previous encryption key.