crypto: return cached copies from CryptoKey algorithm and usages getters

Fixes: #59534
PR-URL: #59538
Fixes: #59535
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Yagiz Nizipli <[email protected]>
Reviewed-By: Rafael Gonzaga <[email protected]>

Author: panva

lib/internal/crypto/keys.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const {
+  ArrayFrom,
   ArrayPrototypeSlice,
   ObjectDefineProperties,
   ObjectDefineProperty,
@@ -81,6 +82,8 @@ const kAlgorithm = Symbol('kAlgorithm');
 const kExtractable = Symbol('kExtractable');
 const kKeyType = Symbol('kKeyType');
 const kKeyUsages = Symbol('kKeyUsages');
+const kCachedAlgorithm = Symbol('kCachedAlgorithm');
+const kCachedKeyUsages = Symbol('kCachedKeyUsages');
 
 // Key input contexts.
 const kConsumePublic = 0;
@@ -835,13 +838,19 @@ class CryptoKey {
   get algorithm() {
     if (!(this instanceof CryptoKey))
       throw new ERR_INVALID_THIS('CryptoKey');
-    return this[kAlgorithm];
+    if (!this[kCachedAlgorithm]) {
+      this[kCachedAlgorithm] ??= { ...this[kAlgorithm] };
+      this[kCachedAlgorithm].hash &&= { ...this[kCachedAlgorithm].hash };
+      this[kCachedAlgorithm].publicExponent &&= new Uint8Array(this[kCachedAlgorithm].publicExponent);
+    }
+    return this[kCachedAlgorithm];
   }
 
   get usages() {
     if (!(this instanceof CryptoKey))
       throw new ERR_INVALID_THIS('CryptoKey');
-    return this[kKeyUsages];
+    this[kCachedKeyUsages] ??= ArrayFrom(this[kKeyUsages]);
+    return this[kCachedKeyUsages];
   }
 }
 

test/parallel/test-webcrypto-internal-slots.mjs

@@ -0,0 +1,21 @@
+import * as common from '../common/index.mjs';
+
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+import * as assert from 'node:assert';
+import * as util from 'node:util';
+
+const { subtle } = globalThis.crypto;
+
+const kp = await subtle.generateKey('Ed25519', true, ['sign', 'verify']);
+assert.notStrictEqual(kp.publicKey.algorithm, kp.privateKey.algorithm);
+assert.notStrictEqual(kp.publicKey.usages, kp.privateKey.usages);
+kp.publicKey.algorithm.name = 'ed25519';
+assert.strictEqual(kp.publicKey.algorithm.name, 'ed25519');
+kp.publicKey.usages.push('foo');
+assert.ok(kp.publicKey.usages.includes('foo'));
+assert.ok(util.inspect(kp.publicKey).includes("algorithm: { name: 'Ed25519' }"));
+assert.ok(util.inspect(kp.publicKey).includes("usages: [ 'verify' ]"));
+
+await subtle.sign('Ed25519', kp.privateKey, Buffer.alloc(32));