问Bouncycastle解密PKCS8

EN

var bytesToDecrypt = Convert.FromBase64String(base64Input);

            AsymmetricCipherKeyPair keyPair;
            var decryptEngine = new Pkcs1Encoding(new RsaEngine());

            using (var txtreader = new StringReader(privateKey))
            {
                keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();

                decryptEngine.Init(false, keyPair.Private);
            }

            var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
            return decrypted;

-----BEGIN PRIVATE KEY-----
...
-----END PRIVATE KEY-----