mirror of
https://github.com/moparisthebest/keepass2android
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127 lines
3.3 KiB
C#
127 lines
3.3 KiB
C#
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/*
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KeePass Password Safe - The Open-Source Password Manager
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Copyright (C) 2003-2016 Dominik Reichl <dominik.reichl@t-online.de>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Security.Cryptography;
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using System.Text;
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using KeePassLib.Utility;
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namespace KeePassLib.Cryptography
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{
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public static class CryptoUtil
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{
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public static byte[] HashSha256(byte[] pbData)
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{
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if(pbData == null) throw new ArgumentNullException("pbData");
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return HashSha256(pbData, 0, pbData.Length);
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}
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public static byte[] HashSha256(byte[] pbData, int iOffset, int cbCount)
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{
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if(pbData == null) throw new ArgumentNullException("pbData");
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#if DEBUG
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byte[] pbCopy = new byte[pbData.Length];
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Array.Copy(pbData, pbCopy, pbData.Length);
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#endif
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byte[] pbHash;
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using(SHA256Managed h = new SHA256Managed())
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{
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pbHash = h.ComputeHash(pbData, iOffset, cbCount);
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}
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#if DEBUG
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// Ensure the data has not been modified
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Debug.Assert(MemUtil.ArraysEqual(pbData, pbCopy));
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Debug.Assert((pbHash != null) && (pbHash.Length == 32));
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byte[] pbZero = new byte[32];
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Debug.Assert(!MemUtil.ArraysEqual(pbHash, pbZero));
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#endif
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return pbHash;
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}
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/// <summary>
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/// Create a cryptographic key of length <paramref name="cbOut" />
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/// (in bytes) from <paramref name="pbIn" />.
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/// </summary>
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public static byte[] ResizeKey(byte[] pbIn, int iInOffset,
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int cbIn, int cbOut)
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{
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if(pbIn == null) throw new ArgumentNullException("pbIn");
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if(cbOut < 0) throw new ArgumentOutOfRangeException("cbOut");
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if(cbOut == 0) return MemUtil.EmptyByteArray;
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byte[] pbHash;
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if(cbOut <= 32) pbHash = HashSha256(pbIn, iInOffset, cbIn);
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else
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{
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using(SHA512Managed h = new SHA512Managed())
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{
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pbHash = h.ComputeHash(pbIn, iInOffset, cbIn);
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}
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}
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if(cbOut == pbHash.Length) return pbHash;
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byte[] pbRet = new byte[cbOut];
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if(cbOut < pbHash.Length)
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Array.Copy(pbHash, pbRet, cbOut);
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else
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{
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int iPos = 0;
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ulong r = 0;
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while(iPos < cbOut)
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{
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Debug.Assert(pbHash.Length == 64);
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using(HMACSHA256 h = new HMACSHA256(pbHash))
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{
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byte[] pbR = MemUtil.UInt64ToBytes(r);
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byte[] pbPart = h.ComputeHash(pbR);
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int cbCopy = Math.Min(cbOut - iPos, pbPart.Length);
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Debug.Assert(cbCopy > 0);
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Array.Copy(pbPart, 0, pbRet, iPos, cbCopy);
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iPos += cbCopy;
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++r;
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MemUtil.ZeroByteArray(pbPart);
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}
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}
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Debug.Assert(iPos == cbOut);
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}
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#if DEBUG
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byte[] pbZero = new byte[pbHash.Length];
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Debug.Assert(!MemUtil.ArraysEqual(pbHash, pbZero));
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#endif
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MemUtil.ZeroByteArray(pbHash);
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return pbRet;
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}
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}
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}
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