From: Chris Duncan <chris@zoso.dev>
Date: Mon, 4 Aug 2025 21:55:24 +0000 (-0700)
Subject: Refactor BIP-44 to allow additional chain and address parameters, allowing Nano which... 
X-Git-Tag: v0.10.5~46^2~6
X-Git-Url: https://git.codecow.com/?a=commitdiff_plain;h=5cdfaf37acd26bccd85745abb853173497675405;p=libnemo.git

Refactor BIP-44 to allow additional chain and address parameters, allowing Nano which uses neither to still resolve.
---

diff --git a/src/lib/bip44-ckd.ts b/src/lib/bip44-ckd.ts
index 5377a64..82bfdc3 100644
--- a/src/lib/bip44-ckd.ts
+++ b/src/lib/bip44-ckd.ts
@@ -1,39 +1,40 @@
 //! SPDX-FileCopyrightText: 2025 Chris Duncan <chris@zoso.dev>
 //! SPDX-License-Identifier: GPL-3.0-or-later
 
+import { BIP44_PURPOSE, HARDENED_OFFSET, SLIP10_ED25519 } from './constants'
+
 type ExtendedKey = {
 	privateKey: DataView<ArrayBuffer>
 	chainCode: DataView
 }
 
 export class Bip44Ckd {
-	static BIP44_COIN_NANO = 165
-	static BIP44_PURPOSE = 44
-	static HARDENED_OFFSET = 0x80000000
-	static SLIP10_ED25519 = 'ed25519 seed'
-
 	/**
 	* Derives a private child key for a coin by following the specified BIP-32 and
 	* BIP-44 derivation path. Purpose is always 44'. Only hardened child keys are
 	* defined.
 	*
 	* @param {ArrayBuffer} seed - Hexadecimal seed derived from mnemonic phrase
-	* @param {number} index - Account number between 0 and 2^31-1
-	* @param {number} coin - Number registered to a specific coin in SLIP-044. Default: 165 (Nano)
+	* @param {number} coin - Number registered to a specific coin in SLIP-044
+	* @param {number} account - Account number between 0 and 2^31-1
 	* @returns {Promise<ArrayBuffer>} Private child key for the account
 	*/
-	static async ckd (seed: ArrayBuffer, index: number, coin: number = this.BIP44_COIN_NANO): Promise<ArrayBuffer> {
+	static async ckd (seed: ArrayBuffer, coin: number, account: number, chain?: number, address?: number): Promise<ArrayBuffer> {
 		if (seed.byteLength < 16 || seed.byteLength > 64) {
 			throw new RangeError(`Invalid seed length`)
 		}
-		if (!Number.isSafeInteger(index) || index < 0 || index > 0x7fffffff) {
-			throw new RangeError(`Invalid child key index 0x${index.toString(16)}`)
+		if (!Number.isSafeInteger(account) || account < 0 || account > 0x7fffffff) {
+			throw new RangeError(`Invalid child key index 0x${account.toString(16)}`)
 		}
-		const masterKey = await this.slip10(this.SLIP10_ED25519, seed)
-		const purposeKey = await this.CKDpriv(masterKey, this.BIP44_PURPOSE + this.HARDENED_OFFSET)
-		const coinKey = await this.CKDpriv(purposeKey, coin + this.HARDENED_OFFSET)
-		const accountKey = await this.CKDpriv(coinKey, index + this.HARDENED_OFFSET)
-		return accountKey.privateKey.buffer
+		const masterKey = await this.slip10(SLIP10_ED25519, seed)
+		const purposeKey = await this.CKDpriv(masterKey, BIP44_PURPOSE + HARDENED_OFFSET)
+		const coinKey = await this.CKDpriv(purposeKey, coin + HARDENED_OFFSET)
+		const accountKey = await this.CKDpriv(coinKey, account + HARDENED_OFFSET)
+		if (chain == null) return accountKey.privateKey.buffer
+		const chainKey = await this.CKDpriv(accountKey, chain)
+		if (address == null) return chainKey.privateKey.buffer
+		const addressKey = await this.CKDpriv(chainKey, address)
+		return addressKey.privateKey.buffer
 	}
 
 	static async slip10 (curve: string, S: ArrayBuffer): Promise<ExtendedKey> {
diff --git a/src/lib/safe.ts b/src/lib/safe.ts
index 9838fc9..81e7516 100644
--- a/src/lib/safe.ts
+++ b/src/lib/safe.ts
@@ -145,7 +145,7 @@ export class Safe {
 				throw new Error('Invalid wallet account index')
 			}
 			const prv = this.#type === 'BIP-44'
-				? await Bip44Ckd.ckd(this.#seed, index)
+				? await Bip44Ckd.ckd(this.#seed, BIP44_COIN_NANO, index)
 				: await Blake2bCkd.ckd(this.#seed, index)
 			const pub = await NanoNaCl.convert(new Uint8Array(prv))
 			return { index, publicKey: pub.buffer }
@@ -233,7 +233,7 @@ export class Safe {
 			if (data == null) {
 				throw new Error('Data to sign not found')
 			}
-			const prv = await Bip44Ckd.ckd(this.#seed, index)
+			const prv = await Bip44Ckd.ckd(this.#seed, BIP44_COIN_NANO, index)
 			const sig = await NanoNaCl.detached(new Uint8Array(data), new Uint8Array(prv))
 			return { signature: sig.buffer }
 		} catch (err) {