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// Copyright (C) 2011, Kenneth Skovhede
// http://www.hexad.dk, opensource@hexad.dk
//
// 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using System.Collections.Generic;
using System.IO;
using Newtonsoft.Json;
using System.Text;
using Duplicati.Library.Main.Database;
namespace Duplicati.Library.Main
{
public class Utility
{
/// <summary>
/// Implementation of the IMetahash interface
/// </summary>
private class Metahash : IMetahash
{
/// <summary>
/// The base64 encoded hash
/// </summary>
private readonly string m_hash;
/// <summary>
/// The UTF-8 encoded json element with the metadata
/// </summary>
private readonly byte[] m_blob;
/// <summary>
/// The lookup table with elements
/// </summary>
private readonly Dictionary<string, string> m_values;
public Metahash(Dictionary<string, string> values, Options options)
{
m_values = values;
var hasher = System.Security.Cryptography.HashAlgorithm.Create(options.BlockHashAlgorithm);
if (hasher == null)
throw new Exception(string.Format(Strings.Foresthash.InvalidHashAlgorithm, options.BlockHashAlgorithm));
if (!hasher.CanReuseTransform)
throw new Exception(string.Format(Strings.Foresthash.InvalidCryptoSystem, options.BlockHashAlgorithm));
using (var ms = new System.IO.MemoryStream())
using (var w = new StreamWriter(ms, Encoding.UTF8))
{
w.Write(JsonConvert.SerializeObject(values));
w.Flush();
m_blob = ms.ToArray();
ms.Position = 0;
m_hash = Convert.ToBase64String(hasher.ComputeHash(ms));
}
}
public string Hash
{
get { return m_hash; }
}
public long Size
{
get { return m_blob.Length; }
}
public byte[] Blob
{
get { return m_blob; }
}
public Dictionary<string, string> Values
{
get { return m_values; }
}
}
/// <summary>
/// Constructs a container for a given metadata dictionary
/// </summary>
/// <param name="values">The metadata values to wrap</param>
/// <returns>A IMetahash instance</returns>
public static IMetahash WrapMetadata(Dictionary<string, string> values, Options options)
{
return new Metahash(values, options);
}
internal static void VerifyParameters(LocalDatabase db, Options options)
{
var newDict = new Dictionary<string, string>();
newDict.Add("blocksize", options.Blocksize.ToString());
newDict.Add("blockhash", options.BlockHashAlgorithm);
newDict.Add("filehash", options.FileHashAlgorithm);
var opts = db.GetDbOptions();
if (options.NoEncryption)
{
newDict.Add("passphrase", "no-encryption");
}
else
{
string salt;
opts.TryGetValue("passphrase-salt", out salt);
if (string.IsNullOrEmpty(salt))
{
// Not Crypto-class PRNG salts
var buf = new byte[32];
new Random().NextBytes(buf);
//Add version so we can detect and change the algorithm
salt = "v1:" + Library.Utility.Utility.ByteArrayAsHexString(buf);
}
newDict["passphrase-salt"] = salt;
// We avoid storing the passphrase directly,
// instead we salt and rehash repeatedly
newDict.Add("passphrase", Library.Utility.Utility.ByteArrayAsHexString(Library.Utility.Utility.RepeatedHashWithSalt(options.Passphrase, salt, 1200)));
}
var needsUpdate = false;
foreach(var k in newDict)
if (!opts.ContainsKey(k.Key))
needsUpdate = true;
else if (opts[k.Key] != k.Value)
{
if (k.Key == "passphrase")
{
if (!options.AllowPassphraseChange)
{
if (newDict[k.Key] == "no-encryption")
throw new Exception("Unsupported removal of passphrase");
else if (opts[k.Key] == "no-encryption")
throw new Exception("Unsupported addition of passphrase");
else
throw new Exception("Unsupported change of passphrase");
}
}
else
throw new Exception(string.Format("Unsupported change of parameter \"{0}\" from \"{1}\" to \"{2}\"", k.Key, opts[k.Key], k.Value));
}
//Extra sanity check
if (db.GetBlocksLargerThan(options.Blocksize) > 0)
throw new Exception("Unsupported block-size change detected");
if (needsUpdate)
db.SetDbOptions(newDict);
}
}
}
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