Function certified_data_set 

pub fn certified_data_set<T>(data: T)
where
    T: AsRef<[u8]>,

Sets the certified data of this canister.

Canisters can store up to 32 bytes of data that is certified by the system on a regular basis. One can call data_certificate function from a query call to get a certificate authenticating the value set by calling this function.

This function can only be called from the following contexts:

• canister_init, canister_pre_upgrade and canister_post_upgrade hooks.
• canister_update calls.
• reply or reject callbacks.

Panics

• This function traps if data.len() > 32.
• This function traps if it’s called from an illegal context (e.g., from a query call).