XCI-Explorer/XTSSharp/Xts.cs

using System;
using System.Security.Cryptography;

namespace XTSSharp
{
	public class Xts
	{
		private readonly SymmetricAlgorithm _key1;

		private readonly SymmetricAlgorithm _key2;

		protected Xts(Func<SymmetricAlgorithm> create, byte[] key1, byte[] key2)
		{
			if (create == null)
			{
				throw new ArgumentNullException("create");
			}
			if (key1 == null)
			{
				throw new ArgumentNullException("key1");
			}
			if (key2 == null)
			{
				throw new ArgumentNullException("key2");
			}
			_key1 = create();
			_key2 = create();
			if (key1.Length != key2.Length)
			{
				throw new ArgumentException("Key lengths don't match");
			}
			_key1.KeySize = key1.Length * 8;
			_key2.KeySize = key2.Length * 8;
			_key1.Key = key1;
			_key2.Key = key2;
			_key1.Mode = CipherMode.ECB;
			_key2.Mode = CipherMode.ECB;
			_key1.Padding = PaddingMode.None;
			_key2.Padding = PaddingMode.None;
			_key1.BlockSize = 128;
			_key2.BlockSize = 128;
		}

		public XtsCryptoTransform CreateEncryptor()
		{
			return new XtsCryptoTransform(_key1.CreateEncryptor(), _key2.CreateEncryptor(), false);
		}

		public XtsCryptoTransform CreateDecryptor()
		{
			return new XtsCryptoTransform(_key1.CreateDecryptor(), _key2.CreateEncryptor(), true);
		}

		protected static byte[] VerifyKey(int expectedSize, byte[] key)
		{
			if (key == null)
			{
				throw new ArgumentNullException("key");
			}
			if (key.Length * 8 != expectedSize)
			{
				throw new ArgumentException($"Expected key length of {expectedSize} bits, got {key.Length * 8}");
			}
			return key;
		}
	}
}