From ea4849410133acf7b2d83ec661fc6ec223b4e2e2 Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Sat, 26 Jul 2025 22:10:57 -0700
Subject: [PATCH] Refactor data extraction into separate function.

---
 src/lib/workers/passkey.ts | 46 +++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/src/lib/workers/passkey.ts b/src/lib/workers/passkey.ts
index e98f79d..2082fbe 100644
--- a/src/lib/workers/passkey.ts
+++ b/src/lib/workers/passkey.ts
@@ -14,8 +14,19 @@ export class Passkey extends WorkerInterface {
 		this.listen()
 	}
 
-	static async work (data: NamedData | unknown): Promise<NamedData> {
-		let method, password, salt
+	static async work (data: NamedData | unknown): Promise<NamedData<ArrayBuffer | CryptoKey>> {
+		const { purpose, password, salt } = this.#extractData(data)
+		try {
+			const key = await this.#createAesKey(purpose, password, salt)
+			return { salt, key }
+		} catch (err) {
+			throw new Error('Failed to derive key from password', { cause: err })
+		} finally {
+			password.transfer()
+		}
+	}
+
+	static #extractData (data: unknown) {
 		if (data == null) {
 			throw new TypeError('Worker received no data')
 		}
@@ -26,29 +37,22 @@ export class Passkey extends WorkerInterface {
 		if (!('password' in dataObject) || !(dataObject.password instanceof ArrayBuffer)) {
 			throw new TypeError('Password must be ArrayBuffer')
 		}
-		password = dataObject.password
-		if (!('method' in dataObject)) {
-			throw new TypeError('Method is required')
+		const password: ArrayBuffer = dataObject.password
+		if (!('purpose' in dataObject)) {
+			throw new TypeError('Key purpose is required')
 		}
-		if (dataObject.method !== 'encrypt' && dataObject.method !== 'decrypt') {
-			throw new TypeError('Invalid method')
+		if (dataObject.purpose !== 'encrypt' && dataObject.purpose !== 'decrypt') {
+			throw new TypeError('Invalid key purpose')
 		}
-		method = dataObject.method as typeof dataObject.method
-		if (method === 'decrypt') {
-			if (!('salt' in dataObject) || !(dataObject.salt instanceof ArrayBuffer)) {
-				throw new TypeError('Salt required for decryption key')
-			}
-			salt = dataObject.salt
+		const purpose: 'encrypt' | 'decrypt' = dataObject.purpose
+		if (purpose === 'decrypt' && !('salt' in dataObject)) {
+			throw new TypeError('Salt required for decryption key')
 		}
-		try {
-			salt ??= globalThis.crypto.getRandomValues(new Uint8Array(32)).buffer
-			const key = await this.#createAesKey(method, password, salt)
-			return { salt, key }
-		} catch (err) {
-			throw new Error('Failed to derive key from password', { cause: err })
-		} finally {
-			password.transfer()
+		if (dataObject.salt != null && !(dataObject.salt instanceof ArrayBuffer)) {
+			throw new TypeError('Salt must be ArrayBuffer')
 		}
+		const salt: ArrayBuffer = dataObject.salt ?? globalThis.crypto.getRandomValues(new Uint8Array(32)).buffer
+		return { purpose, password, salt }
 	}
 
 	static async #createAesKey (purpose: 'encrypt' | 'decrypt', password: ArrayBuffer, salt: ArrayBuffer): Promise<CryptoKey> {
-- 
2.47.3