feat[auth]: custom hasher & api key validation

Co-authored-by: Ona <no-reply@ona.com>

packages/auth/hasher.ts

@@ -0,0 +1,89 @@
+export interface PassswordHasher {
+	hash(password: string): Promise<string>
+	verify(password: string, hash: string): Promise<boolean>
+}
+
+export class BunSha256Hasher implements PassswordHasher {
+	async hash(password: string): Promise<string> {
+		const hasher = new Bun.CryptoHasher("sha256")
+		hasher.update(password)
+		return hasher.digest("base64url")
+	}
+
+	async verify(password: string, hash: string): Promise<boolean> {
+		const hasher = new Bun.CryptoHasher("sha256")
+		hasher.update(password)
+
+		const passwordHash = hasher.digest()
+		const hashBytes = Buffer.from(hash, "base64url")
+
+		if (passwordHash.byteLength !== hashBytes.byteLength) {
+			return false
+		}
+
+		return crypto.timingSafeEqual(passwordHash, hashBytes)
+	}
+}
+
+export class WebCryptoSha256Hasher implements PassswordHasher {
+	async hash(password: string): Promise<string> {
+		const hash = await crypto.subtle.digest(
+			"SHA-256",
+			new TextEncoder().encode(password),
+		)
+		return this.arrayBufferToBase64url(hash)
+	}
+
+	async verify(password: string, hash: string): Promise<boolean> {
+		const passwordHash = await crypto.subtle.digest(
+			"SHA-256",
+			new TextEncoder().encode(password),
+		)
+		const hashBytes = this.base64urlToArrayBuffer(hash)
+
+		if (passwordHash.byteLength !== hashBytes.byteLength) {
+			return false
+		}
+
+		// Timing-safe comparison
+		const passwordHashBytes = new Uint8Array(passwordHash)
+		let result = 0
+		for (let i = 0; i < passwordHashBytes.length; i++) {
+			result |= passwordHashBytes[i]! ^ hashBytes[i]!
+		}
+		return result === 0
+	}
+
+	private arrayBufferToBase64url(buffer: ArrayBuffer): string {
+		const bytes = new Uint8Array(buffer)
+		let binary = ""
+		for (let i = 0; i < bytes.length; i++) {
+			binary += String.fromCharCode(bytes[i]!)
+		}
+		return btoa(binary).replace(/[+/=]/g, (char) => {
+			switch (char) {
+				case "+": return "-"
+				case "/": return "_"
+				case "=": return ""
+				default: return char
+			}
+		})
+	}
+
+	private base64urlToArrayBuffer(base64url: string): Uint8Array {
+		const base64 = base64url.replace(/-/g, "+").replace(/_/g, "/")
+
+		const padded = base64.padEnd(
+			base64.length + ((4 - (base64.length % 4)) % 4),
+			"=",
+		)
+
+		const binary = atob(padded)
+		const bytes = new Uint8Array(binary.length)
+		for (let i = 0; i < binary.length; i++) {
+			bytes[i] = binary.charCodeAt(i)
+		}
+
+		return bytes
+	}
+}

packages/auth/index.ts

@@ -1,3 +1,7 @@
+import { BunSha256Hasher, type PassswordHasher } from "./hasher"
+
+export { WebCryptoSha256Hasher } from "./hasher"
+
 /**
  * An unhashed api key.
  * Always starts with sk, then the prefix specified at time of generation,
@@ -7,6 +11,11 @@ export type UnhashedApiKey = `sk-${ApiKeyPrefix}-${string}`
 
 export type ApiKeyPrefix = string & { __brand: "ApiKeyPrefix" }
 
+export type ParsedApiKey = {
+	prefix: ApiKeyPrefix
+	unhashedKey: UnhashedApiKey
+}
+
 export type GenerateApiKeyOptions = {
 	/**
 	 * How long the key should be (excluding prefix) in bytes.
@@ -21,6 +30,8 @@ export type GenerateApiKeyOptions = {
 
 	expiresAt?: Date
 	description: string
+
+	hasher?: PassswordHasher
 }
 
 export type GenerateApiKeyResult = {
@@ -30,11 +41,21 @@ export type GenerateApiKeyResult = {
 	description: string
 }
 
+export type VerifyApiKeyOptions = {
+	keyToBeVerified: UnhashedApiKey
+	hashedKey: string
+	hasher?: PassswordHasher
+}
+
+function validatePrefix(prefix: string): prefix is ApiKeyPrefix {
+	return !prefix.includes("-")
+}
+
 export function newPrefix(prefix: string): ApiKeyPrefix | null {
-	if (prefix.includes("-")) {
+	if (!validatePrefix(prefix)) {
 		return null
 	}
-	return prefix as ApiKeyPrefix
+	return prefix
 }
 
 export async function generateApiKey({
@@ -42,6 +63,7 @@ export async function generateApiKey({
 	prefix,
 	expiresAt,
 	description,
+	hasher = new BunSha256Hasher(),
 }: GenerateApiKeyOptions): Promise<GenerateApiKeyResult> {
 	const keyContent = new Uint8Array(keyByteLength)
 	crypto.getRandomValues(keyContent)
@@ -49,11 +71,7 @@ export async function generateApiKey({
 	const base64KeyContent = Buffer.from(keyContent).toString("base64url")
 	const unhashedKey: UnhashedApiKey = `sk-${prefix}-${base64KeyContent}`
 
-	const hashedKey = await Bun.password.hash(unhashedKey, {
+	const hashedKey = await hasher.hash(unhashedKey)
-		algorithm: "argon2id",
-		memoryCost: 4, // memory usage in kibibytes
-		timeCost: 3, // the number of iterations
-	})
 
 	return {
 		unhashedKey,
@@ -62,3 +80,29 @@ export async function generateApiKey({
 		description,
 	}
 }
+
+export function parseApiKey(key: string): ParsedApiKey | null {
+	if (!key.startsWith("sk-")) {
+		return null
+	}
+	const parts = key.split("-")
+	if (parts.length !== 3) {
+		return null
+	}
+	const prefix = parts[1]
+	if (!prefix || !validatePrefix(prefix)) {
+		return null
+	}
+	return {
+		prefix,
+		unhashedKey: key as UnhashedApiKey,
+	}
+}
+
+export async function verifyApiKey({
+	keyToBeVerified,
+	hashedKey,
+	hasher = new BunSha256Hasher(),
+}: VerifyApiKeyOptions): Promise<boolean> {
+	return await hasher.verify(keyToBeVerified, hashedKey)
+}