simple AES code, C#

From memory, you pass the string to be encrypted/decrypted and the passphrase as a single string, separated by a comma. I think that was because this was also to be used in a DLL for use with Delphi etc, but anyway, the point is that this was the simple means of setting up and tearing down AES in C#. Apologies for lack of comments, easier to just strip than to have to sanitise too much for the web.


using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;

namespace BlahLib
{
    public interface IBlahLib
    {
        void TestMethod();

        string Encrypt(string original, string key);
        string Decrypt(string encrypted, string key);
        string GetKey(string passphrase);
    }

    [ClassInterface(ClassInterfaceType.None)]
    public class BlahLib : IBlahLib
    {
        public BlahLib()
        {
        }

        public void TestMethod()
        {
            MessageBox.Show("Hello from the BlahLib class");
        }

        public string GetKey(string passphrase)
        {
            RijndaelManaged aesEncryption = new RijndaelManaged();
            aesEncryption.KeySize = 256;
            aesEncryption.BlockSize = 128;
            aesEncryption.Mode = CipherMode.ECB;
            aesEncryption.Padding = PaddingMode.Zeros;
            aesEncryption.GenerateIV();

            string ivStr = Convert.ToBase64String(aesEncryption.IV);
            byte[] keyText = ASCIIEncoding.UTF8.GetBytes(passphrase);
            string keyStr = Convert.ToBase64String(keyText);
            string completeKey = ivStr + "," + keyStr;
            return Convert.ToBase64String(ASCIIEncoding.UTF8.GetBytes(completeKey));
        }

        public string Encrypt(string original, string key)
        {
            RijndaelManaged aesEncryption = new RijndaelManaged();
            aesEncryption.KeySize = 256;
            aesEncryption.BlockSize = 128;
            aesEncryption.Mode = CipherMode.ECB;
            aesEncryption.Padding = PaddingMode.Zeros;
            aesEncryption.IV =
                Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(key)).Split(',')[0]);
            aesEncryption.Key =
                Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(key)).Split(',')[1]);

            byte[] plainText = ASCIIEncoding.UTF8.GetBytes(original);
            ICryptoTransform crypto = aesEncryption.CreateEncryptor();

            byte[] cipherText = crypto.TransformFinalBlock(plainText, 0, plainText.Length);
            return Convert.ToBase64String(cipherText);
        }

        public string Decrypt(string encrypted, string key)
        {
            RijndaelManaged aesEncryption = new RijndaelManaged();
            aesEncryption.KeySize = 256;
            aesEncryption.BlockSize = 128;
            aesEncryption.Mode = CipherMode.ECB;
            aesEncryption.Padding = PaddingMode.Zeros;
            aesEncryption.IV =
                Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(key)).Split(',')[0]);
            aesEncryption.Key =
                Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(key)).Split(',')[1]);

            ICryptoTransform decrypto = aesEncryption.CreateDecryptor();

            byte[] encryptedText = Convert.FromBase64CharArray(encrypted.ToCharArray(), 0, encrypted.Length);
            return ASCIIEncoding.UTF8.GetString(decrypto.TransformFinalBlock(encryptedText, 0, encryptedText.Length));
        }


    }
}