HOPR is a two-layer network with communication and incentivization mechanisms.
HOPR is a privacy-networking protocol able to communicate and transfer messages securely. This is defined by a payment layer, which is a distributed ledger technology (DLT) or blockchain infrastructure able to open payment channels on behalf of HOPR nodes running the HOPR network.
In its first implementation, HOPR relies on the Ethereum blockchain as its payment layer. Using Ethereum smart contracts, we open payment channels on behalf of HOPR nodes that forward messages. Message senders attach HOPR tokens in their messages, which upon successful delivery are paid to the HOPR nodes that relayed the message.
To achieve this, a HOPR node implements a connector interface that communicates to the Ethereum Blockchain using its popular web library, web3js. These interfaces allow HOPR nodes to monitor, approve, sign and verify when a message is transferred, and thus close a state channel and receive their earned HOPR Tokens. Each HOPR node verifies one another, avoiding foul play and rewarding only honest relayers.
Although the first instantiation of the HOPR network is on the Ethereum blockchain, HOPR is chain agnostic, which means that HOPR nodes can eventually implement different payment channels in different blockchains.
At the time of writing, HOPR is also able to implement a Polkadot-enabled payment gateway.