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using System;
using System.IO;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Cms;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto.IO;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.Utilities.IO;
namespace Org.BouncyCastle.Cms
{
/**
* General class for generating a compressed CMS message stream.
* <p>
* A simple example of usage.
* </p>
* <pre>
* CMSCompressedDataStreamGenerator gen = new CMSCompressedDataStreamGenerator();
*
* Stream cOut = gen.Open(outputStream, CMSCompressedDataStreamGenerator.ZLIB);
*
* cOut.Write(data);
*
* cOut.Close();
* </pre>
*/
public class CmsCompressedDataStreamGenerator
{
public static readonly string ZLib = CmsObjectIdentifiers.ZlibCompress.Id;
private int _bufferSize;
/**
* base constructor
*/
public CmsCompressedDataStreamGenerator()
{
}
/**
* Set the underlying string size for encapsulated data
*
* @param bufferSize length of octet strings to buffer the data.
*/
public void SetBufferSize(int bufferSize)
{
_bufferSize = bufferSize;
}
public Stream Open(Stream outStream)
{
return Open(outStream, CmsObjectIdentifiers.Data.Id, ZLib);
}
public Stream Open(Stream outStream, string compressionOid)
{
return Open(outStream, CmsObjectIdentifiers.Data.Id, compressionOid);
}
public Stream Open(Stream outStream, string contentOid, string compressionOid)
{
if (ZLib != compressionOid)
throw new ArgumentException("Unsupported compression algorithm: " + compressionOid,
nameof(compressionOid));
BerSequenceGenerator sGen = new BerSequenceGenerator(outStream);
sGen.AddObject(CmsObjectIdentifiers.CompressedData);
//
// Compressed Data
//
BerSequenceGenerator cGen = new BerSequenceGenerator(
sGen.GetRawOutputStream(), 0, true);
// CMSVersion
cGen.AddObject(new DerInteger(0));
// CompressionAlgorithmIdentifier
cGen.AddObject(new AlgorithmIdentifier(CmsObjectIdentifiers.ZlibCompress));
//
// Encapsulated ContentInfo
//
BerSequenceGenerator eiGen = new BerSequenceGenerator(cGen.GetRawOutputStream());
eiGen.AddObject(new DerObjectIdentifier(contentOid));
Stream octetStream = CmsUtilities.CreateBerOctetOutputStream(
eiGen.GetRawOutputStream(), 0, true, _bufferSize);
return new CmsCompressedOutputStream(
Utilities.IO.Compression.ZLib.CompressOutput(octetStream, -1), sGen, cGen, eiGen);
}
private class CmsCompressedOutputStream
: BaseOutputStream
{
private Stream _out;
private BerSequenceGenerator _sGen;
private BerSequenceGenerator _cGen;
private BerSequenceGenerator _eiGen;
internal CmsCompressedOutputStream(
Stream outStream,
BerSequenceGenerator sGen,
BerSequenceGenerator cGen,
BerSequenceGenerator eiGen)
{
_out = outStream;
_sGen = sGen;
_cGen = cGen;
_eiGen = eiGen;
}
public override void Write(byte[] buffer, int offset, int count)
{
_out.Write(buffer, offset, count);
}
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
public override void Write(ReadOnlySpan<byte> buffer)
{
_out.Write(buffer);
}
#endif
public override void WriteByte(byte value)
{
_out.WriteByte(value);
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
Platform.Dispose(_out);
// TODO Parent context(s) should really be be closed explicitly
_eiGen.Close();
_cGen.Close();
_sGen.Close();
}
base.Dispose(disposing);
}
}
}
}
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