crypto/src/cms/CMSCompressedDataGenerator.cs


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67

using System;
using System.IO;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Cms;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Cms
{
    /**
    * General class for generating a compressed CMS message.
    * <p>
    * A simple example of usage.</p>
    * <p>
    * <pre>
    *      CMSCompressedDataGenerator fact = new CMSCompressedDataGenerator();
    *      CMSCompressedData data = fact.Generate(content, algorithm);
    * </pre>
	* </p>
    */
    public class CmsCompressedDataGenerator
    {
        public static readonly string ZLib = CmsObjectIdentifiers.ZlibCompress.Id;

        public CmsCompressedDataGenerator()
        {
        }

		/**
        * Generate an object that contains an CMS Compressed Data
        */
        public CmsCompressedData Generate(CmsProcessable content, string compressionOid)
        {
            if (ZLib != compressionOid)
                throw new ArgumentException("Unsupported compression algorithm: " + compressionOid,
                    nameof(compressionOid));

            AlgorithmIdentifier comAlgId;
            Asn1OctetString comOcts;

            try
            {
                MemoryStream bOut = new MemoryStream();
                Stream zOut = Utilities.IO.Compression.ZLib.CompressOutput(bOut, -1);

				content.Write(zOut);

                Platform.Dispose(zOut);

                comAlgId = new AlgorithmIdentifier(CmsObjectIdentifiers.ZlibCompress);
				comOcts = new BerOctetString(bOut.ToArray());
            }
            catch (IOException e)
            {
                throw new CmsException("exception encoding data.", e);
            }

            ContentInfo comContent = new ContentInfo(CmsObjectIdentifiers.Data, comOcts);
            ContentInfo contentInfo = new ContentInfo(
                CmsObjectIdentifiers.CompressedData,
                new CompressedData(comAlgId, comContent));

			return new CmsCompressedData(contentInfo);
        }
    }
}