Function group_cipher_create 

pub unsafe extern "C" fn group_cipher_create(
    cipher: *mut *mut group_cipher,
    store: *mut signal_protocol_store_context,
    sender_key_id: *const signal_protocol_sender_key_name,
    global_context: *mut signal_context,
) -> c_int

Construct a group cipher for encrypt/decrypt operations.

The store and global contexts must remain valid for the lifetime of the group cipher.

When finished, free the returned instance by calling group_cipher_free().

@param cipher set to a freshly allocated group cipher instance @param store the signal_protocol_store_context to store all state information in @param sender_key_id the sender that messages will be encrypted to or decrypted from @param global_context the global library context @return 0 on success, or negative on failure