fixup! pkey/rsa: port RSA#{private,public}_{encrypt,decrypt} to the EVP API

Author: rhenium

lib/openssl/pkey.rb

@@ -83,6 +83,7 @@ class RSA
     # OpenSSL::PKey#sign_raw and OpenSSL::PKey#verify_raw instead.
     def private_encrypt(string, padding = PKCS1_PADDING)
       n or raise OpenSSL::PKey::RSAError, "incomplete RSA"
+      private? or raise OpenSSL::PKey::RSAError, "private key needed."
       begin
         sign_raw(nil, string, {
           "rsa_padding_mode" => translate_padding_mode(padding),
@@ -144,6 +145,7 @@ def public_encrypt(data, padding = PKCS1_PADDING)
     # OpenSSL::PKey#encrypt and OpenSSL::PKey#decrypt instead.
     def private_decrypt(data, padding = PKCS1_PADDING)
       n or raise OpenSSL::PKey::RSAError, "incomplete RSA"
+      private? or raise OpenSSL::PKey::RSAError, "private key needed."
       begin
         decrypt(data, {
           "rsa_padding_mode" => translate_padding_mode(padding),