• 

  Guy Swartwout May 15, 2015 18:36

  I had trouble in .NET until I used openssl from one of our Linux boxes to create my key pair. Then I used OpenSSLKey (http://www.jensign.com/opensslkey/) to read the private key. Here's a little sample console app that decrypts an XML file downloaded from iFormBuilder.

  using JavaScience;
  using System;
  using System.IO;
  using System.Security.Cryptography;
  using System.Xml;

  namespace Keys
  {
  class Program
  {
  static void Main(string[] args)
  {
  string fileWithEncryptedFields = @"C:\Temp\keys\dataXML.php.xml";
  string decryptedFile = @"C:\Temp\keys\fixed.xml";
  string[] encryptedFieldNames = new string[] { "encrypted" };

          decryptData(fileWithEncryptedFields, decryptedFile, encryptedFieldNames);
      }
  
      static private void decryptData(string fileWithEncryptedFields, string decryptedFile, string[] encryptedFieldNames)
      {
          string privateKeyFile = @"D:\Transfer\keys\private_key.pem";
  
          RSACryptoServiceProvider rsa = GetRSACryptoServiceProvider(privateKeyFile);
  
          XmlDocument xDoc = new XmlDocument();
          xDoc.Load(fileWithEncryptedFields);
  
          foreach (string encryptedFieldName in encryptedFieldNames)
          {
              XmlNodeList encryptedNodes = xDoc.GetElementsByTagName(encryptedFieldName);
  
              foreach (XmlNode encryptedNode in encryptedNodes)
              {
  
                  byte[] encryptedBytes = Convert.FromBase64String(encryptedNode.InnerText);
                  byte[] decryptedBytes = rsa.Decrypt(encryptedBytes, true);
                  encryptedNode.InnerText = System.Text.Encoding.Default.GetString(decryptedBytes);
              }
          }
  
          xDoc.Save(decryptedFile);
      }
  
      static private RSACryptoServiceProvider GetRSACryptoServiceProvider(string privateKeyFile)
      {
          FileInfo fi = new FileInfo(privateKeyFile);
  
          string overall = "";
          using (StreamReader sr = fi.OpenText())
          {
              overall = sr.ReadToEnd();
              sr.Close();
          }
          using (StreamReader sr = fi.OpenText())
          {
              string rsaPrivKeyString = "";
  
              string tmp = sr.ReadLine().Trim();
              while (!sr.EndOfStream && (tmp.StartsWith("-") || tmp.EndsWith("-")))
                  tmp = sr.ReadLine().Trim();
  
              while (!sr.EndOfStream && !tmp.StartsWith("-") && !tmp.EndsWith("-"))
              {
                  rsaPrivKeyString += tmp;
                  tmp = sr.ReadLine().Trim();
              }
  
              sr.Close();
  
              byte[] data = Convert.FromBase64String(rsaPrivKeyString);
  
              RSACryptoServiceProvider rsa = opensslkey.DecodeRSAPrivateKey(data);
  
              return rsa;
          }
      }
  }
  

  }

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