AES encryption, sample code

Question

Hi,

How do I go about performing AES encryption on a GUID?

On the clients computer we will store a GUID and their public key, and our internal servers will have the private key and their guid.

Is this all the necessary inputs to generate the AES encryption?

Answer 1

AES is a symmetric encryption algorithm (encrypt and decrypt key is the same). If you are talking about public and private keys, you want an asymmetric encryption algorithm such as RSA.

Answer 2

   public static string
   Encrypt (string originalString)
   {
      if (string.IsNullOrEmpty (originalString))
      {
         throw new ArgumentNullException (
            "originalString",
            "The string which needs to be encrypted can not be null.");
      }

      using (var  cryptoProvider = new RijndaelManaged ())
      using (var  memoryStream = new MemoryStream ())
      using (var  cryptoStream = new CryptoStream (
         memoryStream,
         cryptoProvider.CreateEncryptor (rgbKey, rgbIV),
         CryptoStreamMode.Write))
      using (var  writer = new StreamWriter (cryptoStream))
      {
         writer.Write (originalString);
         writer.Flush ();
         cryptoStream.FlushFinalBlock ();
         writer.Flush ();
         return Convert.ToBase64String (memoryStream.GetBuffer (), 0, (int) memoryStream.Length);
      }
   }

   public static string
   Decrypt (string cryptedString)
   {
      if (string.IsNullOrEmpty (cryptedString))
      {
         throw new ArgumentNullException (
            "cryptedString",
            "The string which needs to be decrypted can not be null.");
      }

      using (var  cryptoProvider = new RijndaelManaged ())
      using (var  memoryStream = new MemoryStream (
              Convert.FromBase64String (cryptedString)))
      using (var  cryptoStream = new CryptoStream (
         memoryStream,
         cryptoProvider.CreateDecryptor (rgbKey, rgbIV),
         CryptoStreamMode.Read))
      using (var  reader = new StreamReader (cryptoStream))
      {
         return reader.ReadToEnd ();
      }
   }

   private static byte []  rgbKey = ASCIIEncoding.ASCII.GetBytes ("Ni=9OE=$i+62eprIuDr@ewOu5I9r34Ro"); // change to your own secure key
   private static byte []  rgbIV = ASCIIEncoding.ASCII.GetBytes ("to$eO_e!maI*o3ut"); // change to your own secure initialization vector

Answer 3

You can encrypt anything that can be represented as a stream of bytes. The only ingredient missing from the "recipe" in your question is the encryption key:

void encrypt(char *plaintext, char *key, char *crypt)
{
  // Encrypt plaintext with the key, returning the result in crypt.

}

Notes:

• Using PKI (public/private keys), each participant typically maintains its own private key in a secure manner and freely distributes its public key. Messages are encrypted using the public key of the recipient and decrypted by each recipient with the private key. From the phrasing of the question, it's not apparent that you're using this model.

• Jesse provides a good example for demonstration purposes. Just remember that you probably do not want to hard-code keys in your production application..