crypto: deprecate _toBuf

PR-URL: https://github.com/nodejs/node/pull/22501
Fixes: https://github.com/nodejs/node/issues/22425
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>

doc/api/deprecations.md

@@ -1031,6 +1031,14 @@ With the current crypto API, having `Cipher.setAuthTag()` and
 when called. They have never been documented and will be removed in a future
 release.
 
+<a id="DEP0114"></a>
+### DEP0114: crypto._toBuf()
+
+Type: Runtime
+
+The `crypto._toBuf()` function was not designed to be used by modules outside
+of Node.js core and will be removed in the future.
+
 [`--pending-deprecation`]: cli.html#cli_pending_deprecation
 [`Buffer.allocUnsafeSlow(size)`]: buffer.html#buffer_class_method_buffer_allocunsafeslow_size
 [`Buffer.from(array)`]: buffer.html#buffer_class_method_buffer_from_array

lib/crypto.js

@@ -137,7 +137,7 @@ function createVerify(algorithm, options) {
 
 module.exports = exports = {
   // Methods
-  _toBuf: toBuf,
+  _toBuf: deprecate(toBuf, 'crypto._toBuf is deprecated.', 'DEP0114'),
   createCipheriv,
   createDecipheriv,
   createDiffieHellman,

test/parallel/test-crypto.js

@@ -25,6 +25,13 @@ const common = require('../common');
 if (!common.hasCrypto)
   common.skip('missing crypto');
 
+common.expectWarning({
+  DeprecationWarning: [
+    ['crypto.createCipher is deprecated.', 'DEP0106'],
+    ['crypto._toBuf is deprecated.', 'DEP0114']
+  ]
+});
+
 const assert = require('assert');
 const crypto = require('crypto');
 const tls = require('tls');
@@ -294,3 +301,8 @@ testEncoding({
 testEncoding({
   defaultEncoding: 'latin1'
 }, assertionHashLatin1);
+
+{
+  // Test that the exported _toBuf function is deprecated.
+  crypto._toBuf(Buffer.alloc(0));
+}