From 73ad8deb45e97c9a18d303ef6197d14d83137688 Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Sat, 30 Aug 2025 00:32:14 -0700
Subject: [PATCH] Simplify promise chain.

---
 src/lib/crypto/bip44.ts | 54 +++++++++++++++++------------------------
 1 file changed, 22 insertions(+), 32 deletions(-)

diff --git a/src/lib/crypto/bip44.ts b/src/lib/crypto/bip44.ts
index 8042068..deb200c 100644
--- a/src/lib/crypto/bip44.ts
+++ b/src/lib/crypto/bip44.ts
@@ -29,39 +29,25 @@ export class Bip44 {
 		if (!Number.isSafeInteger(account) || account < 0 || account > 0x7fffffff) {
 			throw new RangeError(`Invalid account index 0x${account.toString(16)}`)
 		}
-		if (change != null && (!Number.isSafeInteger(change) || change < 0 || change > 1)) {
+		if (change !== undefined && (!Number.isSafeInteger(change) || change < 0 || change > 1)) {
 			throw new RangeError(`Invalid change index 0x${account.toString(16)}`)
 		}
-		if (address != null && (!Number.isSafeInteger(address) || address < 0 || address > 0x7fffffff)) {
+		if (address !== undefined && (!Number.isSafeInteger(address) || address < 0 || address > 0x7fffffff)) {
 			throw new RangeError(`Invalid address index 0x${account.toString(16)}`)
 		}
-		return this.#slip10(SLIP10_ED25519, seed)
-			.then(masterKey => {
-				return this.#CKDpriv(masterKey, BIP44_PURPOSE + HARDENED_OFFSET)
-					.then(purposeKey => {
-						return this.#CKDpriv(purposeKey, coin + HARDENED_OFFSET)
-							.then(coinKey => {
-								return this.#CKDpriv(coinKey, account + HARDENED_OFFSET)
-									.then(accountKey => {
-										if (change == null) return accountKey.privateKey
-										return this.#CKDpriv(accountKey, change + HARDENED_OFFSET)
-											.then(chainKey => {
-												if (address == null) return chainKey.privateKey
-												return this.#CKDpriv(chainKey, address + HARDENED_OFFSET)
-													.then(addressKey => {
-														return addressKey.privateKey
-													})
-											})
-									})
-							})
-					})
-			})
+		return this.slip10(SLIP10_ED25519, seed)
+			.then(masterKey => this.CKDpriv(masterKey, BIP44_PURPOSE))
+			.then(purposeKey => this.CKDpriv(purposeKey, coin))
+			.then(coinKey => this.CKDpriv(coinKey, account))
+			.then(accountKey => this.CKDpriv(accountKey, change))
+			.then(chainKey => this.CKDpriv(chainKey, address))
+			.then(addressKey => addressKey.privateKey)
 	}
 
-	static #slip10 (curve: string, S: ArrayBuffer): Promise<ExtendedKey> {
+	static slip10 (curve: string, S: ArrayBuffer): Promise<ExtendedKey> {
 		const key = new Uint8Array(new TextEncoder().encode(curve))
 		const data = new Uint8Array(S)
-		return this.#hmac(key, data)
+		return this.hmac(key, data)
 			.then(I => {
 				const IL = I.slice(0, I.byteLength / 2)
 				const IR = I.slice(I.byteLength / 2)
@@ -69,13 +55,17 @@ export class Bip44 {
 			})
 	}
 
-	static #CKDpriv ({ privateKey, chainCode }: ExtendedKey, index: number): Promise<ExtendedKey> {
+	static CKDpriv ({ privateKey, chainCode }: ExtendedKey, index?: number): Promise<ExtendedKey> {
+		if (index === undefined) {
+			return Promise.resolve({ privateKey, chainCode })
+		}
+		index += HARDENED_OFFSET
 		const key = new Uint8Array(chainCode)
 		const data = new Uint8Array(37)
 		data.set([0])
-		data.set(this.#ser256(privateKey), 1)
-		data.set(this.#ser32(index), 33)
-		return this.#hmac(key, data)
+		data.set(this.ser256(privateKey), 1)
+		data.set(this.ser32(index), 33)
+		return this.hmac(key, data)
 			.then(I => {
 				const IL = I.slice(0, I.byteLength / 2)
 				const IR = I.slice(I.byteLength / 2)
@@ -83,17 +73,17 @@ export class Bip44 {
 			})
 	}
 
-	static #ser32 (integer: number): Uint8Array<ArrayBuffer> {
+	static ser32 (integer: number): Uint8Array<ArrayBuffer> {
 		const view = new DataView(new ArrayBuffer(4))
 		view.setUint32(0, integer, false)
 		return new Uint8Array(view.buffer)
 	}
 
-	static #ser256 (integer: ArrayBuffer): Uint8Array<ArrayBuffer> {
+	static ser256 (integer: ArrayBuffer): Uint8Array<ArrayBuffer> {
 		return new Uint8Array(integer)
 	}
 
-	static #hmac (key: Uint8Array<ArrayBuffer>, data: Uint8Array<ArrayBuffer>): Promise<ArrayBuffer> {
+	static hmac (key: Uint8Array<ArrayBuffer>, data: Uint8Array<ArrayBuffer>): Promise<ArrayBuffer> {
 		return crypto.subtle.importKey('raw', key, { name: 'HMAC', hash: 'SHA-512' }, false, ['sign'])
 			.then(pk => {
 				return crypto.subtle.sign('HMAC', pk, data)
-- 
2.47.3