KEKRecipientInformation.cs
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using System;
using System.IO;
using Org.BouncyCastle.Asn1.Cms;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Cms
{
/**
* the RecipientInfo class for a recipient who has been sent a message
* encrypted using a secret key known to the other side.
*/
public class KekRecipientInformation
: RecipientInformation
{
private KekRecipientInfo info;
internal KekRecipientInformation(
KekRecipientInfo info,
CmsSecureReadable secureReadable)
: base(info.KeyEncryptionAlgorithm, secureReadable)
{
this.info = info;
this.rid = new RecipientID();
KekIdentifier kekId = info.KekID;
rid.KeyIdentifier = kekId.KeyIdentifier.GetOctets();
}
/**
* decrypt the content and return an input stream.
*/
public override CmsTypedStream GetContentStream(
ICipherParameters key)
{
try
{
byte[] encryptedKey = info.EncryptedKey.GetOctets();
IWrapper keyWrapper = WrapperUtilities.GetWrapper(keyEncAlg.Algorithm.Id);
keyWrapper.Init(false, key);
KeyParameter sKey = ParameterUtilities.CreateKeyParameter(
GetContentAlgorithmName(), keyWrapper.Unwrap(encryptedKey, 0, encryptedKey.Length));
return GetContentFromSessionKey(sKey);
}
catch (SecurityUtilityException e)
{
throw new CmsException("couldn't create cipher.", e);
}
catch (InvalidKeyException e)
{
throw new CmsException("key invalid in message.", e);
}
}
}
}