fix(clerk-sdk-node): Properly import key from jwk

packages/sdk-node/src/Clerk.ts

@@ -36,12 +36,10 @@ export type RequireSessionClaimsProp<T> = T & { sessionClaims: JwtPayload };
 
 import { Base } from '@clerk/backend-core';
 import { Crypto, CryptoKey } from '@peculiar/webcrypto';
+import { decodeBase64, toSPKIDer } from './utils/crypto';
 
 const crypto = new Crypto();
 
-const decodeBase64 = (base64: string) =>
-  Buffer.from(base64, 'base64').toString('binary');
-
 const importKey = async (jwk: JsonWebKey, algorithm: Algorithm) => {
   return await crypto.subtle.importKey('jwk', jwk, algorithm, true, ['verify']);
 };
@@ -123,15 +121,12 @@ export default class Clerk extends ClerkBackendAPI {
         cacheMaxAge: jwksCacheMaxAge,
       });
 
-      const encoder = new TextEncoder();
+      const signingKey = await jwksClient.getSigningKey(decoded.header.kid)
+      const pubKey = signingKey.getPublicKey()
 
       return await crypto.subtle.importKey(
-        'raw',
-        encoder.encode(
-          (
-            await jwksClient.getSigningKey(decoded.header.kid)
-          ).getPublicKey() as string
-        ),
+        'spki',
+        toSPKIDer(pubKey),
         {
           name: 'RSASSA-PKCS1-v1_5',
           hash: 'SHA-256',

packages/sdk-node/src/utils/crypto.ts

@@ -0,0 +1,21 @@
+export const decodeBase64 = (base64: string) =>
+  Buffer.from(base64, 'base64').toString('binary');
+
+// toSPKIDer converts a PEM encoded Public Key to DER encoded
+export function toSPKIDer(pem: string): ArrayBuffer {
+  const pemHeader = "-----BEGIN PUBLIC KEY-----";
+  const pemFooter = "-----END PUBLIC KEY-----";
+  const pemContents = pem.substring(pemHeader.length, pem.length - pemFooter.length);
+  const binaryDerString = decodeBase64(pemContents)
+  return str2ab(binaryDerString);
+}
+
+// https://stackoverflow.com/a/11058858
+function str2ab(input: string): ArrayBuffer {
+  const buf = new ArrayBuffer(input.length);
+  const bufView = new Uint8Array(buf);
+  for (let i = 0, strLen = input.length; i < strLen; i++) {
+    bufView[i] = input.charCodeAt(i);
+  }
+  return buf;
+}