/// <summary>
 /// 加密 用的是PEM格式的密钥
 /// </summary>
 /// <param name="plaintext">要加密的数据</param>
 /// <param name="publicPEMKey">PEM格式的公钥</param>
 /// <returns></returns>
 public static string Encrypt_PEMKey(string plaintext, string publicPEMKey)
 {
     using (RSACryptoServiceProvider RSA = RSA_PEM.FromPEM(publicPEMKey))
     {
         return(Encrypt(plaintext, RSA));
     }
 }
 /// <summary>
 /// 解密 用的是PEM格式的密钥
 /// </summary>
 /// <param name="ciphertext">密文</param>
 /// <param name="privatePEMKey">密钥</param>
 /// <returns></returns>
 public static string Decrypt_PEMKey(string ciphertext, string privatePEMKey)
 {
     //using (var RSA = new RSACryptoServiceProvider())
     using (var RSA = RSA_PEM.FromPEM(privatePEMKey))
     {
         return(Decrypt(ciphertext, RSA));
     }
 }