Method to encrypt data and optionally HMAC it.

Encrypt.cs

public string Encrypt(string Data, string KeyName, Func<string> IntegrityFunction)
{
	if (null != IntegrityFunction)
		Data = AddHMAC(Data, IntegrityFunction);
	var val = System.Text.UnicodeEncoding.Unicode.GetBytes(Data);
	using (var crypter = new System.Security.Cryptography.RijndaelManaged())
	{
		var iv = new byte[crypter.BlockSize / 8].FillWithEntropy();
		KeyInfo key = GetKeyInfo(KeyName, iv, crypter);
		byte[] encrypted;
		crypter.IV = iv;
		crypter.Key = key.KeyBytes;
		crypter.Mode = CipherMode.CBC;
		using (var encrypter = crypter.CreateEncryptor())
		{
			using (var to = new MemoryStream())
			{
				using (var writer = new CryptoStream(to, encrypter, CryptoStreamMode.Write))
				{
					writer.Write(val, 0, val.Length);
					writer.FlushFinalBlock();
					encrypted = to.ToArray();
				}
			}
		}
		return string.Format("{0}\0{1}\0{2}", Convert.ToBase64String(iv), Convert.ToBase64String(encrypted), ComputeHMAC(encrypted,key.SecretBytes));
	}
}