crypto: allow promisifying generateKeyPair

PR-URL: #22660 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
nodejs · Sep 21, 2018 · cc82194 · cc82194
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diff --git a/doc/api/crypto.md b/doc/api/crypto.md
@@ -1753,6 +1753,9 @@ buffer containing the data encoded as DER. Note that Node.js itself does not
 accept DER, it is supported for interoperability with other libraries such as
 WebCrypto only.
 
+If this method is invoked as its [`util.promisify()`][]ed version, it returns
+a `Promise` for an `Object` with `publicKey` and `privateKey` properties.
+
 ### crypto.generateKeyPairSync(type, options)
 <!-- YAML
 added: REPLACEME
@@ -2907,6 +2910,7 @@ the `crypto`, `tls`, and `https` modules and are generally specific to OpenSSL.
 [`stream.transform` options]: stream.html#stream_new_stream_transform_options
 [`stream.Writable` options]: stream.html#stream_constructor_new_stream_writable_options
 [`tls.createSecureContext()`]: tls.html#tls_tls_createsecurecontext_options
+[`util.promisify()`]: util.html#util_util_promisify_original
 [`verify.update()`]: #crypto_verify_update_data_inputencoding
 [`verify.verify()`]: #crypto_verify_verify_object_signature_signatureformat
 [AEAD algorithms]: https://en.wikipedia.org/wiki/Authenticated_encryption

diff --git a/lib/internal/crypto/keygen.js b/lib/internal/crypto/keygen.js
@@ -14,6 +14,7 @@ const {
  PK_FORMAT_DER,
  PK_FORMAT_PEM
 } = process.binding('crypto');
+const { customPromisifyArgs } = require('internal/util');
 const { isUint32 } = require('internal/validators');
 const {
  ERR_CRYPTO_INCOMPATIBLE_KEY_OPTIONS,
@@ -43,6 +44,11 @@ function generateKeyPair(type, options, callback) {
  handleError(impl, wrap);
 }
 
+Object.defineProperty(generateKeyPair, customPromisifyArgs, {
+ value: ['publicKey', 'privateKey'],
+ enumerable: false
+});
+
 function generateKeyPairSync(type, options) {
  const impl = check(type, options);
  return handleError(impl);

diff --git a/test/parallel/test-crypto-keygen.js b/test/parallel/test-crypto-keygen.js
@@ -13,6 +13,7 @@ const {
  publicEncrypt,
  privateDecrypt
 } = require('crypto');
+const { promisify } = require('util');
 
 // Asserts that the size of the given key (in chars or bytes) is within 10% of
 // the expected size.
@@ -240,6 +241,34 @@ function convertDERToPEM(label, der) {
  }));
 }
 
+{
+ // Test the util.promisified API with async RSA key generation.
+ promisify(generateKeyPair)('rsa', {
+ publicExponent: 0x10001,
+ modulusLength: 3072,
+ publicKeyEncoding: {
+ type: 'pkcs1',
+ format: 'pem'
+ },
+ privateKeyEncoding: {
+ type: 'pkcs1',
+ format: 'pem'
+ }
+ }).then(common.mustCall((keys) => {
+ const { publicKey, privateKey } = keys;
+ assert.strictEqual(typeof publicKey, 'string');
+ assert(pkcs1PubExp.test(publicKey));
+ assertApproximateSize(publicKey, 600);
+
+ assert.strictEqual(typeof privateKey, 'string');
+ assert(pkcs1PrivExp.test(privateKey));
+ assertApproximateSize(privateKey, 2455);
+
+ testEncryptDecrypt(publicKey, privateKey);
+ testSignVerify(publicKey, privateKey);
+ })).catch(common.mustNotCall());
+}
+
 {
  // Test invalid key types.
  for (const type of [undefined, null, 0]) {