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using System;
using System.IO;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Cms;
using Asn1Pkcs = Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;
namespace Org.BouncyCastle.Cms
{
/**
* the KeyTransRecipientInformation class for a recipient who has been sent a secret
* key encrypted using their public key that needs to be used to
* extract the message.
*/
public class KeyTransRecipientInformation
: RecipientInformation
{
private KeyTransRecipientInfo info;
internal KeyTransRecipientInformation(
KeyTransRecipientInfo info,
CmsSecureReadable secureReadable)
: base(info.KeyEncryptionAlgorithm, secureReadable)
{
this.info = info;
this.rid = new RecipientID();
RecipientIdentifier r = info.RecipientIdentifier;
try
{
if (r.IsTagged)
{
Asn1OctetString octs = Asn1OctetString.GetInstance(r.ID);
rid.SubjectKeyIdentifier = octs.GetOctets();
}
else
{
IssuerAndSerialNumber iAnds = IssuerAndSerialNumber.GetInstance(r.ID);
rid.Issuer = iAnds.Name;
rid.SerialNumber = iAnds.SerialNumber.Value;
}
}
catch (IOException)
{
throw new ArgumentException("invalid rid in KeyTransRecipientInformation");
}
}
private string GetExchangeEncryptionAlgorithmName(
DerObjectIdentifier oid)
{
if (Asn1Pkcs.PkcsObjectIdentifiers.RsaEncryption.Equals(oid))
{
return "RSA//PKCS1Padding";
}
return oid.Id;
}
internal KeyParameter UnwrapKey(ICipherParameters key)
{
byte[] encryptedKey = info.EncryptedKey.GetOctets();
string keyExchangeAlgorithm = GetExchangeEncryptionAlgorithmName(keyEncAlg.ObjectID);
try
{
IWrapper keyWrapper = WrapperUtilities.GetWrapper(keyExchangeAlgorithm);
keyWrapper.Init(false, key);
// FIXME Support for MAC algorithm parameters similar to cipher parameters
return ParameterUtilities.CreateKeyParameter(
GetContentAlgorithmName(), keyWrapper.Unwrap(encryptedKey, 0, encryptedKey.Length));
}
catch (SecurityUtilityException e)
{
throw new CmsException("couldn't create cipher.", e);
}
catch (InvalidKeyException e)
{
throw new CmsException("key invalid in message.", e);
}
// catch (IllegalBlockSizeException e)
catch (DataLengthException e)
{
throw new CmsException("illegal blocksize in message.", e);
}
// catch (BadPaddingException e)
catch (InvalidCipherTextException e)
{
throw new CmsException("bad padding in message.", e);
}
}
/**
* decrypt the content and return it as a byte array.
*/
public override CmsTypedStream GetContentStream(
ICipherParameters key)
{
KeyParameter sKey = UnwrapKey(key);
return GetContentFromSessionKey(sKey);
}
}
}
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