crypto: remove rsaPrivate and rename rsaPublic

This commit renames rsaPublic and removes the rsaPrivate function as the
code in these two functions are identical.

Backport-PR-URL: #20706
PR-URL: #20164
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/internal/crypto/cipher.js

@@ -33,7 +33,7 @@ const { StringDecoder } = require('string_decoder');
 const { inherits } = require('util');
 const { deprecate, normalizeEncoding } = require('internal/util');
 
-function rsaPublic(method, defaultPadding) {
+function rsaFunctionFor(method, defaultPadding) {
   return function(options, buffer) {
     const key = options.key || options;
     const padding = options.padding || defaultPadding;
@@ -42,19 +42,10 @@ function rsaPublic(method, defaultPadding) {
   };
 }
 
-function rsaPrivate(method, defaultPadding) {
-  return function(options, buffer) {
-    const key = options.key || options;
-    const passphrase = options.passphrase || null;
-    const padding = options.padding || defaultPadding;
-    return method(toBuf(key), buffer, padding, passphrase);
-  };
-}
-
-const publicEncrypt = rsaPublic(_publicEncrypt, RSA_PKCS1_OAEP_PADDING);
-const publicDecrypt = rsaPublic(_publicDecrypt, RSA_PKCS1_PADDING);
-const privateEncrypt = rsaPrivate(_privateEncrypt, RSA_PKCS1_PADDING);
-const privateDecrypt = rsaPrivate(_privateDecrypt, RSA_PKCS1_OAEP_PADDING);
+const publicEncrypt = rsaFunctionFor(_publicEncrypt, RSA_PKCS1_OAEP_PADDING);
+const publicDecrypt = rsaFunctionFor(_publicDecrypt, RSA_PKCS1_PADDING);
+const privateEncrypt = rsaFunctionFor(_privateEncrypt, RSA_PKCS1_PADDING);
+const privateDecrypt = rsaFunctionFor(_privateDecrypt, RSA_PKCS1_OAEP_PADDING);
 
 function getDecoder(decoder, encoding) {
   encoding = normalizeEncoding(encoding);