crypto: expose KeyObject.isKeyObject(obj) and CryptoKey.isCryptoKey(obj)

closes #38611

Author: panva

doc/api/crypto.md

@@ -1852,6 +1852,16 @@ passing keys as strings or `Buffer`s due to improved security features.
 The receiver obtains a cloned `KeyObject`, and the `KeyObject` does not need to
 be listed in the `transferList` argument.
 
+### Static method: `KeyObject.isKeyObject(obj)`
+<!-- YAML
+added: REPLACEME
+-->
+
+* `obj` {Object}
+* Returns: {boolean}
+
+Returns `true` if `obj` is a `KeyObject`, `false` otherwise.
+
 ### Static method: `KeyObject.from(key)`
 <!-- YAML
 added: v15.0.0

doc/api/webcrypto.md

@@ -366,6 +366,18 @@ An error will be thrown if the given `typedArray` is larger than 65,536 bytes.
 added: v15.0.0
 -->
 
+### Static method: `CryptoKey.isCryptoKey(obj)`
+<!-- YAML
+added: REPLACEME
+-->
+
+* `obj` {Object}
+* Returns: {boolean}
+
+Returns `true` if `obj` is a `CryptoKey`, `false` otherwise. This method
+is specific to Node.js, it is not portable to other implementations of
+[Web Crypto API][].
+
 ### `cryptoKey.algorithm`
 <!-- YAML
 added: v15.0.0

lib/internal/crypto/keys.js

@@ -116,6 +116,10 @@ const {
       });
     }
 
+    static isKeyObject(obj) {
+      return isKeyObject(obj);
+    }
+
     get type() {
       return this[kKeyType];
     }
@@ -639,8 +643,8 @@ function createPrivateKey(key) {
   return new PrivateKeyObject(handle);
 }
 
-function isKeyObject(key) {
-  return key instanceof KeyObject;
+function isKeyObject(obj) {
+  return obj != null && obj[kHandle] !== undefined;
 }
 
 // Our implementation of CryptoKey is a simple wrapper around a KeyObject
@@ -656,6 +660,10 @@ class CryptoKey extends JSTransferable {
     throw new ERR_OPERATION_FAILED('Illegal constructor');
   }
 
+  static isCryptoKey(obj) {
+    return isCryptoKey(obj);
+  }
+
   [kInspect](depth, options) {
     if (depth < 0)
       return this;