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Core Concepts

This hierarchical deterministic (HD) key derivation scheme is purpose-built for the Spark Wallet and follows the general principles of BIP43. It uses a custom purpose field (8797555’), derived from the last 3 bytes of the SHA256 hash of the string “spark” (0x863d73), to define a new domain of application-specific key derivations.

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Scheme

  • m/8797555’/accountNumber’/0’ - Identity Key
  • m/8797555’/accountNumber’/1’ - Base signing key - As leaf key
  • m/8797555’/accountNumber’/2’ - Temporary signing key - As deposit key
  • m/8797555’/accountNumber’/3’ - Static deposit key

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Account

The accountNumber should start from 0 and use hardened derivation.

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Leaf key derivation

To accept a transfer, there will always be a leaf ID provided by the spark entity. The derivation path for a given leaf id is hash = sha256(leaf_id) From base signing key, the leaf key should be m/8797555’/accountNumber’/1’/hash(leaf_id)%0x80000000 + 0x80000000 (hash(leaf_id)%0x80000000’)

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Deposit address key derivation

For user deposit, there’s no leaf id because the leaf is generated after the tree is created. So user deposit should always use m/8797555’/accountNumber’/2’ And once a deposit tree is created, the user should perform a self transfer to the leaf key.

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Usage in the Spark SDK

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initialize

Initializes your spark wallet
If no account number is provided, our JS-SDK defaults accountNumber to 1 to support backwards compatability for mainnet wallets created with earlier versions of the SDK.

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Parameters

  • mnemonicOrSeed: optional mnemonic or seed
  • accountNumber: optional account number
  • options: wallet configuration parameters

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Usage

// import the SparkWallet spark-sdk
import { SparkWallet } from "@buildonspark/spark-sdk";

// Initialize a new wallet instance
const { wallet, mnemonic } = await SparkWallet.initialize({
  mnemonicOrSeed: "optional-mnemonic-or-seed",
  accountNumber: "optional-account-number",
  options: {
    network: "REGTEST",
  },
});
console.log("Wallet initialized successfully:", mnemonic);