skipjs

A util for:

1. Signing and sending bundles of transactions to the Skip Select auction
2. Sending secure transactions through the Skip Secure RPC to avoid the public mempool

Usage

For signing and sending bundles, skipjs exposes a single default export, SkipBundleClient. SkipBundleClient has two functions: signBundle and sendBundle.

type SignedBundle = {
  transactions: Array<string>
  pubKey: string
  signature: string
}

async signBundle(transactions: string[], privKey: Uint8Array): SignedBundle

async sendBundle(bundle: SignedBundle, desiredHeight: number, sync?: boolean): Promise<object>

For sending secure transactions, skipjs exposes an export, SkipSecureClient, with a single function: sendSecureTransaction.

async sendSecureTransaction(transaction: string)

SkipBundleClient

signBundle

signBundle is used to sign a bundle of transactions. It must be provided with an array of string, and a sepc256k1 private key, used to sign the bundle. The transactions argument should be an array of base64-encoded transaction strings. The encoded bytes can be either Cosmos SDK TxRaws or Ethereum native transactions (such as those produced from ethers, for Ethermint EVM chains. See the examples for more details. signBundle returns a SignedBundle, which can be passed to sendBundle to send the bundle to the Sentinel.

sendBundle

sendBundle sends a SignedBundle to the Sentinel. desiredHeight is the desired height for the bundle to be included on-chain. Submitted bundles will only be considered in the auction for this height. Passing 0 as desiredHeight will cause the Sentinel to consider the bundle for the immediate next height. sync specifies whether to use the async or sync RPC endpoint. If set to true, the promise will not resolve until the bundle has been simulated. If set to false, the promise resolves on bundle submission, prior to its simulation.

Example usage:

Import SkipBundleClient, as well as a way to get an sepc256k1 private key, and other utils for the chain you're using. For this example, we'll use Juno.

import { SkipBundleClient } from '@skip-mev/skipjs'
import { getOfflineSignerProto } from 'cosmjs-utils'
import { juno, getSigningCosmosClient, cosmos } from 'juno-network'
import { chains } from 'chain-registry'

Create your transactions:

const {
    multiSend,
    send
} = cosmos.bank.v1beta1.MessageComposer.fromPartial

var msg = send({
    amount: [
    {
        denom: 'ujuno',
        amount: '10'
    }
    ],
    toAddress: toAddress,
    fromAddress: fromAddress
})

const fee = {
    amount: [
    {
        denom: 'ujuno',
        amount: '864'
    }
    ],
    gas: '86364'
}

Sign your transactions:

const mnemonic = "" // Insert your mnemonic
const signer = await getOfflineSignerProto({
    mnemonic,
    chain: chains.find(({ chain_name }) => chain_name === 'juno')
})

const client = await getSigningCosmosClient({
  rpcEndpoint,
  signer
})

const { accountNumber, sequence } = await client.getSequence(address);
const txRaw = await client.sign(address, [msg], fee, '', {
    accountNumber: accountNumber,
    sequence: sequence,
    chainId: 'juno-1'
})

Convert your TxRaw into a base64 string:

import { TxRaw } from 'cosmjs-types/cosmos/tx/v1beta1/tx.js'
const txString = Buffer.from(TxRaw.encode(txRaw).finish()).toString('base64')

Get the secp256k1 private key for signing the bundle. For example, this can be done with the cosmjs-utils offline signer:

const privKey = (await signer.getAccountsWithPrivkeys())[0].privkey

Create your SkipBundleClient:

const skipBundleClient = new SkipBundleClient(SENTINEL_RPC_ENDPOINT)

The RPC endpoint is an ip:port string that depends on the chain you're using. Skip Sentinel endpoints for each chain can be found here.

Sign and send your bundle:

const signedBundle = await skipBundleClient.signBundle([txString], privKey)
const sendBundleResponse = await skipBundleClient.sendBundle(signedBundle, DESIRED_HEIGHT_FOR_BUNDLE, true)

DESIRED_HEIGHT_FOR_BUNDLE should be a number, where 0 asks the Sentinel to autodetermine the next height.

SkipSecureClient

sendSecureTransaction

sendSecureTransaction is used to send transactions privately through the Skip Secure RPC to keep the transaction hidden from the public mempool. The Sentinel attempts to privately send the transaction to a proposer participating in Skip Select for 5 minutes until discarding the transaction:

1. It takes a single transaction
2. The memo of the transaction must be equal to the sender's address

Example usage:

Import SkipSecureClient, as well as other utils for generating transactions for the chain you're using. For this example, we'll use Juno.

import { SkipSecureClient } from '@skip-mev/skipjs'
import { getOfflineSignerProto } from 'cosmjs-utils'
import { juno, getSigningCosmosClient, cosmos } from 'juno-network'
import { chains } from 'chain-registry'

Create your transactions:

const {
    multiSend,
    send
} = cosmos.bank.v1beta1.MessageComposer.fromPartial

var msg = send({
    amount: [
    {
        denom: 'ujuno',
        amount: '10'
    }
    ],
    toAddress: toAddress,
    fromAddress: fromAddress
})

const fee = {
    amount: [
    {
        denom: 'ujuno',
        amount: '864'
    }
    ],
    gas: '86364'
}

Sign your transactions. Note that the memo of the transaction must be the same as the sender address in order to be accepted by the Sentinel.

const mnemonic = "" // Insert your mnemonic
const signer = await getOfflineSignerProto({
    mnemonic,
    chain: chains.find(({ chain_name }) => chain_name === 'juno')
})

const client = await getSigningCosmosClient({
  rpcEndpoint,
  signer
})

const { accountNumber, sequence } = await client.getSequence(address);
// Note that we use the address for the memo.
const txRaw = await client.sign(address, [msg], fee, address, {
    accountNumber: accountNumber,
    sequence: sequence,
    chainId: 'juno-1'
})

Convert your TxRaw into a base64 string:

import { TxRaw } from 'cosmjs-types/cosmos/tx/v1beta1/tx.js'
const txString = Buffer.from(TxRaw.encode(txRaw).finish()).toString('base64')

Create your SkipSecureClient:

const skipSecureClient = new SkipSecureClient(SENTINEL_RPC_ENDPOINT)

The RPC endpoint is an ip:port string that depends on the chain you're using. Skip Sentinel endpoints for each chain can be found here.

Send your secure transaction:

const sendSecureTransactionResponse = await skipSecureClient.sendSecureTransaction(txString)