I have been supplied with a file that was encrypted on a Unix Solaris 10/SunOS 5.10 machine using the $encrypt method. I believe this to have been done using an aes algorithm.
I need to decrypt this file using C# on a windows machine. I have been supplied with a 16 byte symmetric key but I am unsure how to proceed.
Several code examples I've found mention an IV, block size, padding, cipher mode etc. Unfortunately, I do not know what these are and my research on the standard Unix encrypt method hasn't returned anything useful. I believe I have been supplied with everything I would need to decrypt this on Unix (although I do not have the means to test) - but need this to work on Windows with C#.
Files will be supplied periodically (with the same key), so I need a solution that will work on an on-going basis.
Any helps would be greatly appreciated.
Thanks.
UPDATE:
Thanks to @Maarten (see comments) I now have a working solution:
RijndaelManaged objAlgorithm = new RijndaelManaged();
//set the mode, padding and block size
objAlgorithm.Padding = PaddingMode.PKCS7;
objAlgorithm.Mode = CipherMode.CBC;
objAlgorithm.KeySize = 128;
objAlgorithm.BlockSize = 128;
byte[] key = File.ReadAllBytes(@"PATH_TO_KEY_FILE");
byte[] inputBytes = File.ReadAllBytes(@"PATH_TO_INPUT");
byte[] format = new byte[4];
byte[] iterations = new byte[4];
byte[] IV = new byte[objAlgorithm.BlockSize / 8];
byte[] salt = new byte[16];
byte[] cipherText = new byte[inputBytes.Length - format.Length - iterations.Length - IV.Length - salt.Length];
// Split the input array
Array.Copy(inputBytes, 0, format, 0, format.Length);
Array.Copy(inputBytes, format.Length, iterations, 0, iterations.Length);
Array.Copy(inputBytes, (format.Length + iterations.Length), IV, 0, IV.Length);
Array.Copy(inputBytes, (format.Length + iterations.Length + IV.Length), salt, 0, salt.Length);
Array.Copy(inputBytes, (format.Length + iterations.Length + IV.Length + salt.Length), cipherText, 0, cipherText.Length);
Byte[] outputBytes = cipherText;
string plaintext = string.Empty;
using (MemoryStream memoryStream = new MemoryStream(outputBytes))
{
using (CryptoStream cryptoStream = new CryptoStream(memoryStream, objAlgorithm.CreateDecryptor(key, IV), CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(cryptoStream))
{
try
{
int iReadBytes = cryptoStream.Read(outputBytes, 0, outputBytes.Length);
//plaintext = Encoding.UTF8.GetString(outputBytes,0,outputBytes.Length);
byte[] finalBytes = new byte[iReadBytes];
Array.Copy(outputBytes, 0, finalBytes, 0, iReadBytes);
File.WriteAllBytes(DirectoryPath + strOriginalFileName.Replace(".out", ".xml"), finalBytes);
}
catch (Exception ex)
{
//Handle Error
}
}
}
}
