Remarks

The IV is used for most SymmetricAlgorithm.Mode of operation (except CipherMode.ECB). The value can be made public and must be available when decrypting the data.

IMPORTANT: If you reuse the same DES object for multiple encryption using the same key it is CAPITAL that you use a different IV each time.

C# Example

DES des = DES.Create ();
des.Key = new byte[] { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF };
foreach (string file in files) {
	// each file MUST be encrypted with a different IV
	des.GenerateIV ();
	// encrypt the specified file with our DES key
	EncryptFile (file, des);
}
  

Requirements

Namespace: System.Security.Cryptography
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0