Assorted WebCrypto API fixes

- Accept `Ed25519` algorithm (supported as of cloudflare/workerd#500)
- Return `Ed25519` as the algorithm for `NODE-ED25519` keys
- Mark `X448` and `Ed448` algorithms as unsupported

This passes Miniflare's test suite on Node 16.13.0 and 20.1.0.

It also passes `panva/jose`'s `workerd` tap tests on Node 16.17.0 and
20.1.0. Some of those tests fail on 16.13.0 as support for the
`X25519` algorithm was only added in 16.17.0. See
https://nodejs.org/api/webcrypto.html#web-crypto-api for details.

packages/core/src/standards/crypto.ts

@@ -70,6 +70,20 @@ const usesModernEd25519 = (async () => {
 async function ensureValidNodeAlgorithm(
   algorithm: webcrypto.AlgorithmIdentifier | webcrypto.EcKeyAlgorithm
 ): Promise<webcrypto.AlgorithmIdentifier | webcrypto.EcKeyAlgorithm> {
+  // "X448" and "Ed448" are not supported by Workers
+  if (
+    typeof algorithm === "object" &&
+    (algorithm.name === "X448" || algorithm.name === "Ed448")
+  ) {
+    throw new DOMException("Unrecognized name.", "NotSupportedError");
+  }
+  if (
+    typeof algorithm === "object" &&
+    algorithm.name === "Ed25519" &&
+    !(await usesModernEd25519)
+  ) {
+    return { name: "NODE-ED25519", namedCurve: "NODE-ED25519" };
+  }
   if (
     typeof algorithm === "object" &&
     algorithm.name === "NODE-ED25519" &&
@@ -83,19 +97,19 @@ async function ensureValidNodeAlgorithm(
 }
 
 function ensureValidWorkerKey(key: webcrypto.CryptoKey): webcrypto.CryptoKey {
-  // Users' workers will expect to see the `NODE-ED25519` algorithm, even if
-  // we're using "Ed25519" internally (https://github.com/panva/jose/issues/446)
-  if (key.algorithm.name === "Ed25519") key.algorithm.name = "NODE-ED25519";
+  // Users' workers will expect to see the `Ed25519` algorithm, even if we're
+  // using on an old Node version and using "Ed25519" internally
+  if (key.algorithm.name === "NODE-ED25519") key.algorithm.name = "Ed25519";
   return key;
 }
 
 async function ensureValidNodeKey(
   key: webcrypto.CryptoKey
 ): Promise<webcrypto.CryptoKey> {
-  if (key.algorithm.name === "NODE-ED25519" && (await usesModernEd25519)) {
+  if (key.algorithm.name === "Ed25519" && !(await usesModernEd25519)) {
     return new Proxy(key, {
       get(target, property, receiver) {
-        if (property === "algorithm") return { name: "Ed25519" };
+        if (property === "algorithm") return { name: "NODE-ED25519" };
         return Reflect.get(target, property, receiver);
       },
     });

packages/core/test/standards/crypto.spec.ts

@@ -100,8 +100,8 @@ test("crypto: generateKey/exportKey: supports NODE-ED25519 algorithm", async (t)
     true,
     ["sign", "verify"]
   );
-  t.is(keyPair.publicKey.algorithm.name, "NODE-ED25519");
-  t.is(keyPair.privateKey.algorithm.name, "NODE-ED25519");
+  t.is(keyPair.publicKey.algorithm.name, "Ed25519");
+  t.is(keyPair.privateKey.algorithm.name, "Ed25519");
   const exported = await crypto.subtle.exportKey("raw", keyPair.publicKey);
   t.is(exported.byteLength, 32);
 });
@@ -126,7 +126,7 @@ test("crypto: importKey/exportKey: supports NODE-ED25519 public keys", async (t)
     true,
     ["verify"]
   );
-  t.is(publicKey.algorithm.name, "NODE-ED25519");
+  t.is(publicKey.algorithm.name, "Ed25519");
   const exported = await crypto.subtle.exportKey("raw", publicKey);
   t.is(Buffer.from(exported).toString("hex"), keyData);
 });