Try to gracefully support existing public keys

1 files changed, 33 insertions, 1 deletions

diff --git a/packages/server/src/helpers/convertPublicKeyToPEM.ts b/packages/server/src/helpers/convertPublicKeyToPEM.ts
index a7e04bd..ced4ad7 100644
--- a/packages/server/src/helpers/convertPublicKeyToPEM.ts
+++ b/packages/server/src/helpers/convertPublicKeyToPEM.ts
@@ -3,9 +3,41 @@ import jwkToPem from 'jwk-to-pem';
 import base64url from 'base64url';
 
 import { COSEKEYS, COSEKTY, COSECRV } from './convertCOSEtoPKCS';
+import convertX509CertToPEM from './convertX509CertToPEM';
 
 export default function convertPublicKeyToPEM(publicKey: string): string {
-  const struct = cbor.decodeFirstSync(base64url.toBuffer(publicKey));
+  const publicKeyBuffer = base64url.toBuffer(publicKey);
+  console.log(publicKeyBuffer.toString('hex'));
+
+  let struct;
+  try {
+    struct = cbor.decodeAllSync(publicKeyBuffer)[0];
+  } catch (err) {
+    console.warn('Caught error when trying to decode public key, might be an old public key');
+    /**
+     * Catching an error here means we're probably converting an "old" EC2 public key that was
+     * saved before we started returning the full credentialPublicKey from an attestation.
+     *
+     * We're playing things a little fast and loose by naively converting it to PEM format in a way
+     * that is consistent with how it used to be constructed.
+     *
+     * BTW this is in here to try and prevent better RSA support from breaking existing deployments.
+     * It is strongly recommended that this be deprecated in a future release...
+     */
+    let oldPubKeyPEM = convertX509CertToPEM(
+      Buffer.concat([
+        // Assumes EC keyType with P-256 algorithm
+        Buffer.from('3059301306072a8648ce3d020106082a8648ce3d030107034200', 'hex'),
+        publicKeyBuffer,
+      ]),
+    );
+
+    // Replace "-----BEGIN CERTIFICATE-----" with "-----BEGIN PUBLIC KEY-----" (so we can reuse
+    // the method)
+    oldPubKeyPEM = oldPubKeyPEM.replace(/CERTIFICATE/gi, 'PUBLIC KEY');
+
+    return oldPubKeyPEM;
+  }
 
   const kty = struct.get(COSEKEYS.kty);