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#region Disclaimer / License
// Copyright (C) 2015, The Duplicati Team
// http://www.duplicati.com, info@duplicati.com
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
#endregion
using System;
using System.Collections.Generic;
using System.Text;
using Duplicati.Library.Interface;
using System.IO;
using System.Security.Cryptography;
namespace Duplicati.Library.Encryption
{
/// <summary>
/// Implements AES encryption
/// </summary>
public class AESEncryption : EncryptionBase
{
/// <summary>
/// The commandline option supplied if an explicit thread level should be set (--aes-set-threadlevel)
/// </summary>
private const string COMMANDLINE_SET_THREADLEVEL = "aes-set-threadlevel";
/// <summary>
/// The default thread level
/// </summary>
private static readonly string DEFAULT_THREAD_LEVEL = Math.Min(4, Environment.ProcessorCount).ToString();
/// <summary>
/// The key used to encrypt the data
/// </summary>
private string m_key;
/// <summary>
/// The cached value for size overhead
/// </summary>
private static long m_cachedsizeoverhead = -1;
/// <summary>
/// The thread level to pass to SharpAESCrypt. 0 for default.
/// </summary>
private static int m_usethreadlevel = 0;
/// <summary>
/// Default constructor, used to read file extension and supported commands
/// </summary>
public AESEncryption()
{
}
/// <summary>
/// Constructs a new AES encryption/decyption instance
/// </summary>
/// <param name="key">The key used for encryption. The key gets stretched through SHA hashing to fit the key size requirements</param>
public AESEncryption(string passphrase, Dictionary<string, string> options)
{
if(string.IsNullOrEmpty(passphrase))
throw new ArgumentException(Strings.AESEncryption.EmptyKeyError, nameof(passphrase));
m_key = passphrase;
string strTL;
options.TryGetValue(COMMANDLINE_SET_THREADLEVEL, out strTL);
if (string.IsNullOrWhiteSpace(strTL))
strTL = DEFAULT_THREAD_LEVEL;
int useTL;
if (int.TryParse(strTL, out useTL))
{
// finally set thread level in a range of 0 (default) to 4
m_usethreadlevel = Math.Max(0, (Math.Min(4, useTL)));
}
}
#region IEncryption Members
/// <summary>
/// The extension that the encryption implementation adds to the filename
/// </summary>
/// <value>The filename extension.</value>
public override string FilenameExtension { get { return "aes"; } }
/// <summary>
/// A localized description of the encryption module
/// </summary>
/// <value>The description.</value>
public override string Description { get { return string.Format(Strings.AESEncryption.Description_v2); } }
/// <summary>
/// A localized string describing the encryption module with a friendly name
/// </summary>
/// <value>The display name.</value>
public override string DisplayName { get { return Strings.AESEncryption.DisplayName; } }
/// <summary>
/// Dispose the specified disposing.
/// </summary>
/// <param name="disposing">If set to <c>true</c> disposing.</param>
protected override void Dispose(bool disposing) { m_key = null; }
/// <summary>
/// Returns the size in bytes of the overhead that will be added to a file of the given size when encrypted
/// </summary>
/// <param name="filesize">The size of the file to encrypt</param>
/// <returns>The size of the overhead in bytes</returns>
public override long SizeOverhead(long filesize)
{
if (m_cachedsizeoverhead != -1)
return m_cachedsizeoverhead;
//If we use 1, we trigger the blocksize.
//As the AES algorithm does not alter the size,
// the results are the same as for the real size,
// but a single byte encryption is much faster.
return m_cachedsizeoverhead = base.SizeOverhead(1);
}
/// <summary>
/// Encrypts the stream
/// </summary>
/// <param name="input">The target stream</param>
/// <returns>An encrypted stream that can be written to</returns>
public override Stream Encrypt(Stream input)
{
var cryptoStream = new SharpAESCrypt.SharpAESCrypt(m_key, input, SharpAESCrypt.OperationMode.Encrypt);
if (m_usethreadlevel != 0) cryptoStream.MaxCryptoThreads = m_usethreadlevel;
return cryptoStream;
}
/// <summary>
/// Decrypts the stream to the output stream
/// </summary>
/// <param name="input">The encrypted stream</param>
/// <returns>The unencrypted stream</returns>
public override Stream Decrypt(Stream input)
{
var cryptoStream = new SharpAESCrypt.SharpAESCrypt(m_key, input, SharpAESCrypt.OperationMode.Decrypt);
if (m_usethreadlevel != 0) cryptoStream.MaxCryptoThreads = m_usethreadlevel;
return cryptoStream;
}
/// <summary>
/// Gets a list of supported commandline arguments
/// </summary>
/// <value>The supported commands.</value>
public override IList<ICommandLineArgument> SupportedCommands
{
get
{
return new List<ICommandLineArgument>(new ICommandLineArgument[] {
new CommandLineArgument(
COMMANDLINE_SET_THREADLEVEL,
CommandLineArgument.ArgumentType.Enumeration,
Strings.AESEncryption.AessetthreadlevelShort,
Strings.AESEncryption.AessetthreadlevelLong,
DEFAULT_THREAD_LEVEL,
null,
new string[] {"0", "1", "2", "3", "4"}
),
});
}
}
#endregion
}
}
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