/// <summary>
/// This will decrypt the payload from a downloaded and decompressed notification
/// </summary>
/// <param name="xmlProcessingFolder">The path to folder that contains the decompressed notification files</param>
/// <param name="decryptionKey">The key file used to decrypt the AES key</param>
/// <param name="decryptionPass">The password to the key file above</param>
/// <param name="isECB">Determines the cipher mode, CBC or ECB</param>
/// <returns>the file path to the decrypted payload file</returns>
public static string DecryptNotification(string xmlProcessingFolder, string decryptionKey, string decryptionPass, bool isECB)
{
// select encrypted key file
string encryptedKeyFile = "";
string encryptedPayloadFile = "";
string metadataFile = "";
string[] keyFiles = Directory.GetFiles(xmlProcessingFolder, "*_Key", SearchOption.TopDirectoryOnly);
string[] payloadFiles = Directory.GetFiles(xmlProcessingFolder, "*_Payload", SearchOption.TopDirectoryOnly);
string[] metadataFiles = Directory.GetFiles(xmlProcessingFolder, "*_Metadata*", SearchOption.TopDirectoryOnly);
if (keyFiles.Length == 0)
{
// key file validation
throw new Exception("There was no file found containing the encrypted AES key!");
}
if (payloadFiles.Length == 0)
{
// key file validation
throw new Exception("There was no file found containing the encrypted Payload!");
}
if (metadataFiles.Length == 0)
{
// key file validation
throw new Exception("There was no file found containing the Metadata!");
}
encryptedKeyFile = keyFiles[0];
encryptedPayloadFile = payloadFiles[0];
metadataFile = metadataFiles[0];
//Check the metadata and see what we have
string metadataContentType = XmlManager.CheckMetadataType(metadataFile);
byte[] encryptedAesKey = null;
byte[] decryptedAesKey = null;
byte[] aesVector = null;
string decryptedPayload = "";
// load encrypted AES key
encryptedAesKey = File.ReadAllBytes(encryptedKeyFile);
// decrypt AES key & generate default (empty) initialization vector
decryptedAesKey = AesManager.DecryptAesKey(encryptedAesKey, decryptionKey, decryptionPass);
aesVector = AesManager.GenerateRandomKey(16, true);
if (isECB != true)
{
aesVector = decryptedAesKey.Skip(32).Take(16).ToArray();
decryptedAesKey = decryptedAesKey.Take(32).ToArray();
}
// decrypt encrypted ZIP file using decrypted AES key
string decryptedFileName = encryptedPayloadFile.Replace("_Payload", "_Payload_decrypted.zip");
AesManager.DecryptFile(encryptedPayloadFile, decryptedFileName, decryptedAesKey, aesVector, isECB);
//Deflate the decrypted zip archive
ZipManager.ExtractArchive(decryptedFileName, xmlProcessingFolder, true);
decryptedPayload = decryptedFileName.Replace("_Payload_decrypted.zip", "_Payload.xml");
//If the metadata is something other than XML, read the wrapper and rebuild the non-XML file
if (metadataContentType != "XML")
{
//Some non-XML files may not have _Payload in the file name, if not remove it
if (!File.Exists(decryptedPayload))
{
decryptedPayload = decryptedPayload.Replace("_Payload.xml", ".xml");
}
//This will give us the base64 encoded data from the XML file
string encodedData = XmlManager.ExtractXMLImageData(decryptedPayload);
//We will convert the base64 data back to bytes
byte[] binaryData;
string decodedPayload = decryptedPayload.Replace(".xml", "." + metadataContentType);
binaryData = System.Convert.FromBase64String(encodedData);
//We can write the bytes back to rebuild the file
FileStream decodedFile;
decodedFile = new FileStream(decodedPayload, System.IO.FileMode.Create, System.IO.FileAccess.Write);
decodedFile.Write(binaryData, 0, binaryData.Length);
decodedFile.Close();
}
return(decryptedPayload);
}
private void btnDecryptZip_Click(object sender, EventArgs e)
{
if (string.IsNullOrWhiteSpace(txtNotificationZip.Text) || string.IsNullOrWhiteSpace(txtReceiverCert.Text))
{
// files validation
MessageBox.Show("Either the ZIP file or certificate was not specified!", Text, MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
string zipFolder = "";
try
{
//Deflate the zip archive
zipFolder = ZipManager.ExtractArchive(txtNotificationZip.Text, txtNotificationFolder.Text);
}
catch (Exception ex)
{
ex.DisplayException(Text);
return;
}
// select encrypted key file
string encryptedKeyFile = "";
string encryptedPayloadFile = "";
string metadataFile = "";
string[] keyFiles = Directory.GetFiles(zipFolder, "*_Key", SearchOption.TopDirectoryOnly);
string[] payloadFiles = Directory.GetFiles(zipFolder, "*_Payload", SearchOption.TopDirectoryOnly);
string[] metadataFiles = Directory.GetFiles(zipFolder, "*_Metadata*", SearchOption.TopDirectoryOnly);
if (keyFiles.Length == 0)
{
// key file validation
MessageBox.Show("There was no file found containing the encrypted AES key!", Text, MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
if (payloadFiles.Length == 0)
{
// key file validation
MessageBox.Show("There was no file found containing the encrypted Payload!", Text, MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
encryptedKeyFile = keyFiles[0];
encryptedPayloadFile = payloadFiles[0];
metadataFile = metadataFiles[0];
//Check the metadata and see what we have
string metadataContentType = XmlManager.CheckMetadataType(metadataFile);
byte[] encryptedAesKey = null;
byte[] decryptedAesKey = null;
byte[] aesVector = null;
try
{
// load encrypted AES key
encryptedAesKey = File.ReadAllBytes(encryptedKeyFile);
// decrypt AES key & generate default (empty) initialization vector
decryptedAesKey = AesManager.DecryptAesKey(encryptedAesKey, txtReceiverCert.Text, txtRecKeyPassword.Text);
aesVector = AesManager.GenerateRandomKey(16, true);
if (radECB.Checked != true)
{
aesVector = decryptedAesKey.Skip(32).Take(16).ToArray();
decryptedAesKey = decryptedAesKey.Take(32).ToArray();
}
// decrypt encrypted ZIP file using decrypted AES key
string decryptedFileName = encryptedPayloadFile.Replace("_Payload", "_Payload_decrypted.zip");
AesManager.DecryptFile(encryptedPayloadFile, decryptedFileName, decryptedAesKey, aesVector, radECB.Checked);
//Deflate the decrypted zip archive
ZipManager.ExtractArchive(decryptedFileName, decryptedFileName, false);
string decryptedPayload = decryptedFileName.Replace("_Payload_decrypted.zip", "_Payload.xml");
//If the metadata is something other than XML, read the wrapper and rebuild the non-XML file
if (metadataContentType != "XML")
{
//Some non-XML files may not have _Payload in the file name, if not remove it
if (!File.Exists(decryptedPayload))
{
decryptedPayload = decryptedPayload.Replace("_Payload.xml", ".xml");
}
//This will give us the base64 encoded data from the XML file
string encodedData = XmlManager.ExtractXMLImageData(decryptedPayload);
//We will convert the base64 data back to bytes
byte[] binaryData;
string decodedPayload = decryptedPayload.Replace(".xml", "." + metadataContentType);
binaryData = System.Convert.FromBase64String(encodedData);
//We can write the bytes back to rebuild the file
FileStream decodedFile;
decodedFile = new FileStream(decodedPayload, System.IO.FileMode.Create, System.IO.FileAccess.Write);
decodedFile.Write(binaryData, 0, binaryData.Length);
decodedFile.Close();
}
// success
MessageBox.Show("Notification decryption process is complete!", Text, MessageBoxButtons.OK, MessageBoxIcon.Information);
}
catch (Exception ex)
{
ex.DisplayException(Text);
}
finally
{
if (encryptedAesKey != null)
{
encryptedAesKey = null;
}
if (decryptedAesKey != null)
{
decryptedAesKey = null;
}
if (aesVector != null)
{
aesVector = null;
}
}
}