fairyport

FairyPort is an off-chain service for fetching aggregated keyshares to Destination Chains from FairyRing.

Why FairyPort

To decrypt encrypted transactions on the destination chain, the corresponding aggregated keyshares have to be fetched from the FairyRing Chain to the Destination chain. The straightforward solution of using ICQ (Interchain Query) does not meet the requirements since the verification of blocks on both chains takes up so a lot of blocks, effectively delaying the process by multiple blocks. This opens up avenues for front-running transactions on the Destination Chain since there is a large time gap between Keyshars being published on the FairyRing Chain and the same being registered on the Destination chain.

To solve this issue, FairyPort is introduced

Working Principle

FairyPort is a fairly simple service. It consists of two main components:

1. A websocket client listening for events on the Fairyring Chain
2. A mechanism to make transactions to the Destination Chain

The service constantly listens for Keyshare Aggregation events on the Fairyring Chain. Whenever such a event is recorded in a block, FairyPort makes a transaction to the Destination chain to register the Keyshares. This process completely ignores any kind of block verification. This is because the keyshare being transacted to the Destination Chain can easily be verified on chain and without any further interchain communication. This prevents registration of false or malicious keyshares while also verifying the origin of the KeyShares.

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Installation and Running

To install FairyPort, simply clone the repo and run make install in the root directory. This will install the fairyport binary.

To run Fairyport, first make sure you have the correct configuration (discussed in the next section),

You can initialize the default config by fairyport init

Both the FairyRing chain and the Destination Chain should be running for FairyPort to function properly.

To start the service simply run fairyport start.

Configuration

The following configuration options are available:

• CosmosRelayConfig
  • Destination Node
  • Metrics Port
  • Derive Path
• EVMRelayTarget
  • Chain RPC
  • Contract Address
• FairyringNodeWS
  • IP
  • Port
  • Protocol

EVM_PKEY environment variable is required when relaying to EVM chain.

COSMOS_MNEMONIC environment variable is required when relaying to Cosmos chain.

Cosmos Relay Config

Option	Description
Destination Node	The Destination Cosmos Node to relay to.
Metrics Port	The port that lets prometheus collect metrics
Derive Path	The path Fairyport uses to derive the private key from the mnemonic phase.

Destination Node

Option	Description
IP	The IP address that Destination Cosmos Node.
Port	The port that Destination Cosmos Node will use for TendermintRPC
Protocol	The protocol used for communication via the TendermintRPC
gRPC Port	The port that Destination Node will use for gRPC communication.
Chain ID	The chain id of the destination cosmos chain.
Account Prefix	The account prefix of the Destination Cosmos Chain.

EVM Relay Target

Option	Description
Chain RPC	The WS endpoint to the Destination EVM chain
Contract Address	The Fairyring Contract address on Destination EVM chain

Fairyring Node WS

Option	Description
IP	The IP address of given Fairyring node endpoint.
Port	The Port of the given Fairyring node endpoint.
Protocol	The Protocol of Fairyring node endpoint.

EVM_PKEY & COSMOS_MNEMONIC Environment variable

1. Pass the environemnt variable to fairyport when starting it

EVM_PKEY=your_hex_private_key fairyport start --config $HOME/.fairyport/config.yml

COSMOS_MNEMONIC="mnemonic phase" fairyport start --config $HOME/.fairyport/config.yml

2. Set the environment before running fairyport

export EVM_PKEY=your_hex_private_key
fairyport start --config $HOME/.fairyport/config.yml

export COSMOS_MNEMONIC="mnemonic phase"
fairyport start --config $HOME/.fairyport/config.yml

3. Create a .env file in the same directory you are running fairyport

EVM_PKEY=your_hex_private_key
COSMOS_MNEMONIC="mnemonic phase"

then run fairyport start --config $HOME/.fairyport/config.yml