AW.Pay.Core.RSAFromPkcs8.ConvertFromPrivateKey C# (CSharp) Метод

        private static RSAParameters ConvertFromPrivateKey(string pemFileConent)
        {
            byte[] keyData = Convert.FromBase64String(pemFileConent);
            if (keyData.Length < 609)
            {
                throw new ArgumentException("pem file content is incorrect.");
            }

            int index = 11;
            byte[] pemModulus = new byte[128];
            Array.Copy(keyData, index, pemModulus, 0, 128);

            index += 128;
            index += 2;//141
            byte[] pemPublicExponent = new byte[3];
            Array.Copy(keyData, index, pemPublicExponent, 0, 3);

            index += 3;
            index += 4;//148
            byte[] pemPrivateExponent = new byte[128];
            Array.Copy(keyData, index, pemPrivateExponent, 0, 128);

            index += 128;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//279
            byte[] pemPrime1 = new byte[64];
            Array.Copy(keyData, index, pemPrime1, 0, 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//346
            byte[] pemPrime2 = new byte[64];
            Array.Copy(keyData, index, pemPrime2, 0, 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//412/413
            byte[] pemExponent1 = new byte[64];
            Array.Copy(keyData, index, pemExponent1, 0, 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//479/480
            byte[] pemExponent2 = new byte[64];
            Array.Copy(keyData, index, pemExponent2, 0, 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//545/546
            byte[] pemCoefficient = new byte[64];
            Array.Copy(keyData, index, pemCoefficient, 0, 64);

            RSAParameters para = new RSAParameters();
            para.Modulus = pemModulus;
            para.Exponent = pemPublicExponent;
            para.D = pemPrivateExponent;
            para.P = pemPrime1;
            para.Q = pemPrime2;
            para.DP = pemExponent1;
            para.DQ = pemExponent2;
            para.InverseQ = pemCoefficient;
            return para;
        }
        #endregion