111 lines
3.0 KiB
C#
111 lines
3.0 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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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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.Storage.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, IMetadata 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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