Blink enables the same transactions that would occur on the Loki mainchain to be confirmed before being included in a block, assuring both the sender and the receiver of the validity of the transaction and protecting the receiver against a double spend. Because of Loki’s Service Node architecture, near instant transactions are possible.
In a typical blockchain system, the confirmation time for any given transaction is the time it takes for a transaction to be included in a block. Because of competing miners, withheld blocks, and Finney attacks, recipients usually require a number of additional blocks to be created on top of the block which holds a transaction before it is considered to be complete. Depending on a multitude of factors specific to each blockchain, this process can often take 10-60 minutes, which is inconvenient for merchants and customers who must wait for confirmations before they release goods or commence services.
Blink works in a similar fashion to DASH’s InstantSend. Each block, a Service Node swarm is deterministically selected to act as a set of witnesses that confirm a transactions validity and lock the transaction from being spent twice. Instead of the unspent outputs used in the transaction being locked (like in DASH), key images are locked. Key images are unique keys that are attached to each unspent output in a ring signature. To provide immediate 11 confirmations, Blink gives authority to the selected swarm to signal to the network that a key image associated with an output should be locked until the transaction is included in a block. If a double spend of the same unspent output is attempted, an identical key image is produced, which would be rejected by the swarm and thus the network as a whole.
Users will have the ability to pay a higher fee to send a Blink transaction which will confirm in seconds rather than in minutes. This opens up a range of new use cases for Loki where face-to-face payments become increasingly practical and online payments become easier tonintegrate. All of the privacy features inherent in Loki are uncompromised throughout this process.