package org.bouncycastle.cms;
import java.io.InputStream;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import org.bouncycastle.asn1.cms.KEKIdentifier;
import org.bouncycastle.asn1.cms.KEKRecipientInfo;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
/**
* 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
extends RecipientInformation
{
private KEKRecipientInfo _info;
private AlgorithmIdentifier _encAlg;
public KEKRecipientInformation(
KEKRecipientInfo info,
AlgorithmIdentifier encAlg,
InputStream data)
{
super(encAlg, AlgorithmIdentifier.getInstance(info.getKeyEncryptionAlgorithm()), data);
this._info = info;
this._encAlg = encAlg;
this._rid = new RecipientId();
KEKIdentifier kekId = info.getKekid();
_rid.setKeyIdentifier(kekId.getKeyIdentifier().getOctets());
}
/**
* decrypt the content and return an input stream.
*/
public CMSTypedStream getContentStream(
Key key,
String prov)
throws CMSException, NoSuchProviderException
{
try
{
byte[] encryptedKey = _info.getEncryptedKey().getOctets();
Cipher keyCipher = Cipher.getInstance(_keyEncAlg.getObjectId().getId(), prov);
keyCipher.init(Cipher.UNWRAP_MODE, key);
AlgorithmIdentifier aid = _encAlg;
String alg = aid.getObjectId().getId();
Key sKey = keyCipher.unwrap(
encryptedKey, alg, Cipher.SECRET_KEY);
return getContentFromSessionKey(sKey, prov);
}
catch (NoSuchAlgorithmException e)
{
throw new CMSException("can't find algorithm.", e);
}
catch (InvalidKeyException e)
{
throw new CMSException("key invalid in message.", e);
}
catch (NoSuchPaddingException e)
{
throw new CMSException("required padding not supported.", e);
}
}
}