Write into Storage

1. The contributor creates a new encrypted message via the message module. How the message is encrypted is described in the message module designs.

2. The encrypted message is saved into any storage layer.

3. Optional: The contributor creates a state proof in the identity provider required by the identity consumer to dispatch the call

4. The contributor submits the extrinsic to write into the bucket with the optional state proof. The consumer chain executes the write tx.