.NET使用OpenSSL生成的pem密钥文件(增加size为2048的密钥转换)(2)

            Array.Copy(keyData, (keySize1024? 29:33), pemModulus, 0,(keySize1024?  128:256));
            Array.Copy(keyData, (keySize1024? 159:291), pemPublicExponent, 0, 3);
            RSAParameters para = new RSAParameters();
            para.Modulus = pemModulus;
            para.Exponent = pemPublicExponent;
            return para;
        }

        /// <summary>
        /// 将pem格式私钥(1024 or 2048)转换为RSAParameters
        /// </summary>
        /// <param name="pemFileConent">pem私钥内容</param>
        /// <returns>转换得到的RSAParamenters</returns>
        public static RSAParameters ConvertFromPemPrivateKey(string pemFileConent)
        {
            if (string.IsNullOrEmpty(pemFileConent))
            {
                throw new ArgumentNullException("pemFileConent", "This arg cann't be empty.");
            }
            pemFileConent = pemFileConent.Replace("-----BEGIN RSA PRIVATE KEY-----", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("\n", "").Replace("\r","");
            byte[] keyData = Convert.FromBase64String(pemFileConent);

            bool keySize1024 = (keyData.Length == 609 || keyData.Length == 610);
            bool keySize2048 = (keyData.Length == 1190 || keyData.Length == 1192);
          
            if (!(keySize1024 || keySize2048))
            {
                throw new ArgumentException("pem file content is incorrect, Only support the key size is 1024 or 2048");
            }