120 lines
3.9 KiB
C#
120 lines
3.9 KiB
C#
/*
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*
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* (c) Copyright Ascensio System Limited 2010-2020
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*
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* This program is freeware. You can redistribute it and/or modify it under the terms of the GNU
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* General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html).
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* In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that
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* Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
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*
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* THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
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* FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
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*
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* You can contact Ascensio System SIA by email at sales@onlyoffice.com
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*
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* The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display
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* Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
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*
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* Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains
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* relevant author attributions when distributing the software. If the display of the logo in its graphic
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* form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE"
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* in every copy of the program you distribute.
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* Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
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*
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*/
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using System;
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using System.IO;
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using System.Security.Cryptography;
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namespace ASC.Data.Encryption
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{
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internal sealed class StreamWrapper : Stream
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{
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private readonly Stream stream;
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private readonly CryptoStream cryptoStream;
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private readonly SymmetricAlgorithm symmetricAlgorithm;
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private readonly ICryptoTransform cryptoTransform;
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private readonly long fileSize;
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private readonly long metadataLength;
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public StreamWrapper(Stream fileStream, Metadata metadata)
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{
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stream = fileStream;
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symmetricAlgorithm = metadata.GetCryptographyAlgorithm();
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cryptoTransform = symmetricAlgorithm.CreateDecryptor();
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cryptoStream = new CryptoStreamWrapper(stream, cryptoTransform, CryptoStreamMode.Read);
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fileSize = metadata.GetFileSize();
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metadataLength = metadata.GetMetadataLength();
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}
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public override bool CanRead
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{
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get { return stream.CanRead; }
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}
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public override bool CanSeek
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{
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get { return false; }
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}
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public override bool CanWrite
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{
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get { return false; }
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}
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public override long Length
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{
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get { return fileSize; }
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}
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public override long Position
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{
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get
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{
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return stream.Position - metadataLength;
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}
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set
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{
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if (value < 0 || value > fileSize)
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throw new ArgumentOutOfRangeException();
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stream.Position = value + metadataLength;
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}
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}
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public override void Flush()
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{
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}
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public override int Read(byte[] buffer, int offset, int count)
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{
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return cryptoStream.Read(buffer, offset, count);
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}
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public override long Seek(long offset, SeekOrigin origin)
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{
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throw new NotSupportedException();
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}
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public override void SetLength(long value)
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{
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throw new NotSupportedException();
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}
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public override void Write(byte[] buffer, int offset, int count)
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{
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throw new NotSupportedException();
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}
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public override void Close()
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{
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cryptoStream.Dispose();
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stream.Dispose();
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symmetricAlgorithm.Dispose();
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cryptoTransform.Dispose();
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}
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}
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}
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