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using System;
using System.IO;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Cms;
using Org.BouncyCastle.Asn1.X509;
namespace Org.BouncyCastle.Cms
{
/**
* Parsing class for an CMS Enveloped Data object from an input stream.
* <p>
* Note: that because we are in a streaming mode only one recipient can be tried and it is important
* that the methods on the parser are called in the appropriate order.
* </p>
* <p>
* Example of use - assuming the first recipient matches the private key we have.
* <pre>
* CmsEnvelopedDataParser ep = new CmsEnvelopedDataParser(inputStream);
*
* RecipientInformationStore recipients = ep.GetRecipientInfos();
*
* Collection c = recipients.getRecipients();
* Iterator it = c.iterator();
*
* if (it.hasNext())
* {
* RecipientInformation recipient = (RecipientInformation)it.next();
*
* CMSTypedStream recData = recipient.getContentStream(privateKey);
*
* processDataStream(recData.getContentStream());
* }
* </pre>
* Note: this class does not introduce buffering - if you are processing large files you should create
* the parser with:
* <pre>
* CmsEnvelopedDataParser ep = new CmsEnvelopedDataParser(new BufferedInputStream(inputStream, bufSize));
* </pre>
* where bufSize is a suitably large buffer size.
* </p>
*/
public class CmsEnvelopedDataParser
: CmsContentInfoParser
{
internal RecipientInformationStore recipientInfoStore;
internal EnvelopedDataParser envelopedData;
private AlgorithmIdentifier _encAlg;
private Asn1.Cms.AttributeTable _unprotectedAttributes;
private bool _attrNotRead;
public CmsEnvelopedDataParser(
byte[] envelopedData)
: this(new MemoryStream(envelopedData, false))
{
}
public CmsEnvelopedDataParser(
Stream envelopedData)
: base(envelopedData)
{
this._attrNotRead = true;
this.envelopedData = new EnvelopedDataParser(
(Asn1SequenceParser)this.contentInfo.GetContent(Asn1Tags.Sequence));
// TODO Validate version?
//DerInteger version = this.envelopedData.Version;
//
// read the recipients
//
Asn1Set recipientInfos = Asn1Set.GetInstance(this.envelopedData.GetRecipientInfos().ToAsn1Object());
//
// read the encrypted content info
//
EncryptedContentInfoParser encInfo = this.envelopedData.GetEncryptedContentInfo();
this._encAlg = encInfo.ContentEncryptionAlgorithm;
CmsReadable readable = new CmsProcessableInputStream(
((Asn1OctetStringParser)encInfo.GetEncryptedContent(Asn1Tags.OctetString)).GetOctetStream());
CmsSecureReadable secureReadable = new CmsEnvelopedHelper.CmsEnvelopedSecureReadable(
this._encAlg, readable);
//
// build the RecipientInformationStore
//
this.recipientInfoStore = CmsEnvelopedHelper.BuildRecipientInformationStore(
recipientInfos, secureReadable);
}
public AlgorithmIdentifier EncryptionAlgorithmID
{
get { return _encAlg; }
}
/**
* return the object identifier for the content encryption algorithm.
*/
public string EncryptionAlgOid
{
get { return _encAlg.Algorithm.Id; }
}
/**
* return the ASN.1 encoded encryption algorithm parameters, or null if
* there aren't any.
*/
public Asn1Object EncryptionAlgParams => _encAlg.Parameters?.ToAsn1Object();
/**
* return a store of the intended recipients for this message
*/
public RecipientInformationStore GetRecipientInfos()
{
return this.recipientInfoStore;
}
/**
* return a table of the unprotected attributes indexed by
* the OID of the attribute.
* @throws IOException
*/
public Asn1.Cms.AttributeTable GetUnprotectedAttributes()
{
if (_unprotectedAttributes == null && _attrNotRead)
{
Asn1SetParser asn1Set = this.envelopedData.GetUnprotectedAttrs();
_attrNotRead = false;
if (asn1Set != null)
{
_unprotectedAttributes = CmsUtilities.ParseAttributeTable(asn1Set);
}
}
return _unprotectedAttributes;
}
}
}
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