keepass2android/src/KeePassLib2Android/Security/ProtectedBinary.cs

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/*
KeePass Password Safe - The Open-Source Password Manager
Copyright (C) 2003-2012 Dominik Reichl <dominik.reichl@t-online.de>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
using System;
using System.Security.Cryptography;
using System.Diagnostics;
using KeePassLib.Cryptography;
using KeePassLib.Utility;
#if KeePassLibSD
using KeePassLibSD;
#endif
namespace KeePassLib.Security
{
/// <summary>
/// Represents a protected binary, i.e. a byte array that is encrypted
/// in memory. A <c>ProtectedBinary</c> object is immutable and
/// thread-safe.
/// </summary>
public sealed class ProtectedBinary : IEquatable<ProtectedBinary>
{
private const int PmBlockSize = 16;
// In-memory protection is supported only on Windows 2000 SP3 and
// higher.
private static bool m_bProtectionSupported;
private byte[] m_pbData; // Never null
// The real length of the data. This value can be different than
// m_pbData.Length, as the length of m_pbData always is a multiple
// of PmBlockSize (required for fast in-memory protection).
private uint m_uDataLen;
private bool m_bProtected;
private object m_objSync = new object();
/// <summary>
/// A flag specifying whether the <c>ProtectedBinary</c> object has
/// turned on in-memory protection or not.
/// </summary>
public bool IsProtected
{
get { return m_bProtected; }
}
/// <summary>
/// Length of the stored data.
/// </summary>
public uint Length
{
get { return m_uDataLen; }
}
static ProtectedBinary()
{
try // Test whether ProtectedMemory is supported
{
byte[] pbDummy = new byte[PmBlockSize * 2];
ProtectedMemory.Protect(pbDummy, MemoryProtectionScope.SameProcess);
m_bProtectionSupported = true;
}
catch(Exception) // Windows 98 / ME
{
m_bProtectionSupported = false;
}
}
/// <summary>
/// Construct a new, empty protected binary data object. Protection
/// is disabled.
/// </summary>
public ProtectedBinary()
{
Init(false, new byte[0]);
}
/// <summary>
/// Construct a new protected binary data object.
/// </summary>
/// <param name="bEnableProtection">If this paremeter is <c>true</c>,
/// the data will be encrypted in memory. If it is <c>false</c>, the
/// data is stored in plain-text in the process memory.</param>
/// <param name="pbData">Value of the protected object.
/// The input parameter is not modified and
/// <c>ProtectedBinary</c> doesn't take ownership of the data,
/// i.e. the caller is responsible for clearing it.</param>
public ProtectedBinary(bool bEnableProtection, byte[] pbData)
{
Init(bEnableProtection, pbData);
}
/// <summary>
/// Construct a new protected binary data object. Copy the data from
/// a <c>XorredBuffer</c> object.
/// </summary>
/// <param name="bEnableProtection">Enable protection or not.</param>
/// <param name="xbProtected"><c>XorredBuffer</c> object used to
/// initialize the <c>ProtectedBinary</c> object.</param>
/// <exception cref="System.ArgumentNullException">Thrown if the input
/// parameter is <c>null</c>.</exception>
public ProtectedBinary(bool bEnableProtection, XorredBuffer xbProtected)
{
Debug.Assert(xbProtected != null); if(xbProtected == null) throw new ArgumentNullException("xbProtected");
byte[] pb = xbProtected.ReadPlainText();
Init(bEnableProtection, pb);
MemUtil.ZeroByteArray(pb);
}
private void Init(bool bEnableProtection, byte[] pbData)
{
if(pbData == null) throw new ArgumentNullException("pbData");
m_bProtected = bEnableProtection;
m_uDataLen = (uint)pbData.Length;
int nBlocks = (int)m_uDataLen / PmBlockSize;
if((nBlocks * PmBlockSize) < (int)m_uDataLen) ++nBlocks;
Debug.Assert((nBlocks * PmBlockSize) >= (int)m_uDataLen);
m_pbData = new byte[nBlocks * PmBlockSize];
Array.Copy(pbData, m_pbData, (int)m_uDataLen);
// Data size must be > 0, otherwise 'Protect' throws
if(m_bProtected && m_bProtectionSupported && (m_uDataLen > 0))
ProtectedMemory.Protect(m_pbData, MemoryProtectionScope.SameProcess);
}
/// <summary>
/// Get a copy of the protected data as a byte array.
/// Please note that the returned byte array is not protected and
/// can therefore been read by any other application.
/// Make sure that your clear it properly after usage.
/// </summary>
/// <returns>Unprotected byte array. This is always a copy of the internal
/// protected data and can therefore be cleared safely.</returns>
public byte[] ReadData()
{
if(m_uDataLen == 0) return new byte[0];
byte[] pbReturn = new byte[m_uDataLen];
if(m_bProtected && m_bProtectionSupported)
{
lock(m_objSync)
{
ProtectedMemory.Unprotect(m_pbData, MemoryProtectionScope.SameProcess);
Array.Copy(m_pbData, pbReturn, (int)m_uDataLen);
ProtectedMemory.Protect(m_pbData, MemoryProtectionScope.SameProcess);
}
}
else Array.Copy(m_pbData, pbReturn, (int)m_uDataLen);
return pbReturn;
}
/// <summary>
/// Read the protected data and return it protected with a sequence
/// of bytes generated by a random stream.
/// </summary>
/// <param name="crsRandomSource">Random number source.</param>
/// <returns>Protected data.</returns>
/// <exception cref="System.ArgumentNullException">Thrown if the input
/// parameter is <c>null</c>.</exception>
public byte[] ReadXorredData(CryptoRandomStream crsRandomSource)
{
Debug.Assert(crsRandomSource != null);
if(crsRandomSource == null) throw new ArgumentNullException("crsRandomSource");
byte[] pbData = ReadData();
uint uLen = (uint)pbData.Length;
byte[] randomPad = crsRandomSource.GetRandomBytes(uLen);
Debug.Assert(randomPad.Length == uLen);
for(uint i = 0; i < uLen; ++i)
pbData[i] ^= randomPad[i];
return pbData;
}
public override int GetHashCode()
{
int h = (m_bProtected ? 0x7B11D289 : 0);
byte[] pb = ReadData();
unchecked
{
for(int i = 0; i < pb.Length; ++i)
h = (h << 3) + h + (int)pb[i];
}
MemUtil.ZeroByteArray(pb);
return h;
}
public override bool Equals(object obj)
{
return Equals(obj as ProtectedBinary);
}
public bool Equals(ProtectedBinary other)
{
if(other == null) return false; // No assert
if(m_bProtected != other.m_bProtected) return false;
if(m_uDataLen != other.m_uDataLen) return false;
byte[] pbL = ReadData();
byte[] pbR = other.ReadData();
bool bEq = MemUtil.ArraysEqual(pbL, pbR);
MemUtil.ZeroByteArray(pbL);
MemUtil.ZeroByteArray(pbR);
#if DEBUG
if(bEq) { Debug.Assert(GetHashCode() == other.GetHashCode()); }
#endif
return bEq;
}
}
}