/// <summary>
/// 通过一个pem文件创建RSA，pem为公钥或私钥，出错抛异常
/// </summary>
public RSA(string pem, bool noop)
{
_init();
rsa = RSA_PEM.FromPEM(pem);
}
/// <summary>
/// 导出PEM PKCS#8格式密钥对，如果convertToPublic含私钥的RSA将只返回公钥，仅含公钥的RSA不受影响
/// </summary>
public string ToPEM_PKCS8(bool convertToPublic = false)
{
return(RSA_PEM.ToPEM(rsa, convertToPublic, true));
}