  Digital notarization is one of the most promising services offered by modern
blockchain-based solutions. We present a digital notary design with incremental
security and cost reduced with respect to current solutions. A client of the
service receives evidence in three steps. In the first step, evidence is
received almost immediately, but a lot of trust is required. In the second
step, less trust is required, but evidence is received seconds later. Finally,
in the third step evidence is received within minutes via a public blockchain.
