crypto: add KeyObject.asymmetricKeySize

Expose the size of asymetric keys of crypto key object from the
crypto module added in v11.6.0.

PR-URL: nodejs#26387
Refs: nodejs#24234
Reviewed-By: Ben Noordhuis <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

Author: paroga

doc/api/crypto.md

@@ -1121,6 +1121,15 @@ exposes different functions.
 Most applications should consider using the new `KeyObject` API instead of
 passing keys as strings or `Buffer`s due to improved security features.
 
+### keyObject.asymmetricKeySize
+<!-- YAML
+added: REPLACEME
+-->
+* {number}
+
+For asymmetric keys, this property represents the size of the embedded key in
+bytes. This property is `undefined` for symmetric keys.
+
 ### keyObject.asymmetricKeyType
 <!-- YAML
 added: v11.6.0

lib/internal/crypto/keys.js

@@ -73,9 +73,15 @@ class SecretKeyObject extends KeyObject {
   }
 }
 
+const kAsymmetricKeySize = Symbol('kAsymmetricKeySize');
 const kAsymmetricKeyType = Symbol('kAsymmetricKeyType');
 
 class AsymmetricKeyObject extends KeyObject {
+  get asymmetricKeySize() {
+    return this[kAsymmetricKeySize] ||
+           (this[kAsymmetricKeySize] = this[kHandle].getAsymmetricKeySize());
+  }
+
   get asymmetricKeyType() {
     return this[kAsymmetricKeyType] ||
            (this[kAsymmetricKeyType] = this[kHandle].getAsymmetricKeyType());

src/node_crypto.cc

@@ -3330,6 +3330,8 @@ Local<Function> KeyObject::Initialize(Environment* env, Local<Object> target) {
   t->InstanceTemplate()->SetInternalFieldCount(1);
 
   env->SetProtoMethod(t, "init", Init);
+  env->SetProtoMethodNoSideEffect(t, "getAsymmetricKeySize",
+                                  GetAsymmetricKeySize);
   env->SetProtoMethodNoSideEffect(t, "getSymmetricKeySize",
                                   GetSymmetricKeySize);
   env->SetProtoMethodNoSideEffect(t, "getAsymmetricKeyType",
@@ -3375,6 +3377,11 @@ const char* KeyObject::GetSymmetricKey() const {
   return this->symmetric_key_.get();
 }
 
+size_t KeyObject::GetAsymmetricKeySize() const {
+  CHECK_NE(key_type_, kKeyTypeSecret);
+  return EVP_PKEY_size(this->asymmetric_key_.get());
+}
+
 size_t KeyObject::GetSymmetricKeySize() const {
   CHECK_EQ(key_type_, kKeyTypeSecret);
   return this->symmetric_key_len_;
@@ -3474,6 +3481,12 @@ void KeyObject::GetAsymmetricKeyType(const FunctionCallbackInfo<Value>& args) {
   args.GetReturnValue().Set(key->GetAsymmetricKeyType());
 }
 
+void KeyObject::GetAsymmetricKeySize(const FunctionCallbackInfo<Value>& args) {
+  KeyObject* key;
+  ASSIGN_OR_RETURN_UNWRAP(&key, args.Holder());
+  args.GetReturnValue().Set(static_cast<uint32_t>(key->GetAsymmetricKeySize()));
+}
+
 void KeyObject::GetSymmetricKeySize(const FunctionCallbackInfo<Value>& args) {
   KeyObject* key;
   ASSIGN_OR_RETURN_UNWRAP(&key, args.Holder());

src/node_crypto.h

@@ -456,6 +456,7 @@ class KeyObject : public BaseObject {
   // only be used to implement cryptograohic operations requiring the key.
   ManagedEVPPKey GetAsymmetricKey() const;
   const char* GetSymmetricKey() const;
+  size_t GetAsymmetricKeySize() const;
   size_t GetSymmetricKeySize() const;
 
  protected:
@@ -470,6 +471,9 @@ class KeyObject : public BaseObject {
       const v8::FunctionCallbackInfo<v8::Value>& args);
   v8::Local<v8::String> GetAsymmetricKeyType() const;
 
+  static void GetAsymmetricKeySize(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
+
   static void GetSymmetricKeySize(
       const v8::FunctionCallbackInfo<v8::Value>& args);
 

test/parallel/test-crypto-key-objects.js

@@ -38,6 +38,7 @@ const privatePem = fixtures.readSync('test_rsa_privkey.pem', 'ascii');
   const key = createSecretKey(keybuf);
   assert.strictEqual(key.type, 'secret');
   assert.strictEqual(key.symmetricKeySize, 32);
+  assert.strictEqual(key.asymmetricKeySize, undefined);
   assert.strictEqual(key.asymmetricKeyType, undefined);
 
   const exportedKey = key.export();
@@ -91,11 +92,13 @@ const privatePem = fixtures.readSync('test_rsa_privkey.pem', 'ascii');
   const publicKey = createPublicKey(publicPem);
   assert.strictEqual(publicKey.type, 'public');
   assert.strictEqual(publicKey.asymmetricKeyType, 'rsa');
+  assert.strictEqual(publicKey.asymmetricKeySize, 128);
   assert.strictEqual(publicKey.symmetricKeySize, undefined);
 
   const privateKey = createPrivateKey(privatePem);
   assert.strictEqual(privateKey.type, 'private');
   assert.strictEqual(privateKey.asymmetricKeyType, 'rsa');
+  assert.strictEqual(privateKey.asymmetricKeySize, 128);
   assert.strictEqual(privateKey.symmetricKeySize, undefined);
 
   // It should be possible to derive a public key from a private key.

test/parallel/test-crypto-keygen.js

@@ -108,10 +108,12 @@ const sec1EncExp = (cipher) => getRegExpForPEM('EC PRIVATE KEY', cipher);
   assert.strictEqual(typeof publicKey, 'object');
   assert.strictEqual(publicKey.type, 'public');
   assert.strictEqual(publicKey.asymmetricKeyType, 'rsa');
+  assert.strictEqual(publicKey.asymmetricKeySize, 64);
 
   assert.strictEqual(typeof privateKey, 'object');
   assert.strictEqual(privateKey.type, 'private');
   assert.strictEqual(privateKey.asymmetricKeyType, 'rsa');
+  assert.strictEqual(publicKey.asymmetricKeySize, 64);
 }
 
 {
@@ -453,6 +455,7 @@ const sec1EncExp = (cipher) => getRegExpForPEM('EC PRIVATE KEY', cipher);
     assert.strictEqual(typeof publicKey, 'object');
     assert.strictEqual(publicKey.type, 'public');
     assert.strictEqual(publicKey.asymmetricKeyType, 'rsa');
+    assert.strictEqual(publicKey.asymmetricKeySize, 128);
 
     // The private key should still be a string.
     assert.strictEqual(typeof privateKey, 'string');
@@ -477,6 +480,7 @@ const sec1EncExp = (cipher) => getRegExpForPEM('EC PRIVATE KEY', cipher);
     assert.strictEqual(typeof privateKey, 'object');
     assert.strictEqual(privateKey.type, 'private');
     assert.strictEqual(privateKey.asymmetricKeyType, 'rsa');
+    assert.strictEqual(privateKey.asymmetricKeySize, 128);
 
     testEncryptDecrypt(publicKey, privateKey);
     testSignVerify(publicKey, privateKey);