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The Bouncy Castle Java CMS and S/MIME APIs for handling the CMS and S/MIME protocols. This jar contains CMS and S/MIME APIs for JDK 1.6. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs. If the S/MIME API is used, the JavaMail API and the Java activation framework will also be needed.
package org.bouncycastle.cms;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.cms.PasswordRecipientInfo;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.InputStream;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
/**
* the RecipientInfo class for a recipient who has been sent a message
* encrypted using a password.
*/
public class PasswordRecipientInformation
extends RecipientInformation
{
private PasswordRecipientInfo _info;
private AlgorithmIdentifier _encAlg;
public PasswordRecipientInformation(
PasswordRecipientInfo info,
AlgorithmIdentifier encAlg,
InputStream data)
{
super(encAlg, AlgorithmIdentifier.getInstance(info.getKeyEncryptionAlgorithm()), data);
this._info = info;
this._encAlg = encAlg;
this._rid = new RecipientId();
}
/**
* decrypt the content and return an input stream.
*/
public CMSTypedStream getContentStream(
Key key,
String prov)
throws CMSException, NoSuchProviderException
{
try
{
AlgorithmIdentifier kekAlg = AlgorithmIdentifier.getInstance(_info.getKeyEncryptionAlgorithm());
ASN1Sequence kekAlgParams = (ASN1Sequence)kekAlg.getParameters();
byte[] encryptedKey = _info.getEncryptedKey().getOctets();
String kekAlgName = DERObjectIdentifier.getInstance(kekAlgParams.getObjectAt(0)).getId();
Cipher keyCipher = Cipher.getInstance(
CMSEnvelopedHelper.INSTANCE.getRFC3211WrapperName(kekAlgName), prov);
IvParameterSpec ivSpec = new IvParameterSpec(ASN1OctetString.getInstance(kekAlgParams.getObjectAt(1)).getOctets());
keyCipher.init(Cipher.UNWRAP_MODE, new SecretKeySpec(((CMSPBEKey)key).getEncoded(kekAlgName), kekAlgName), ivSpec);
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);
}
catch (InvalidAlgorithmParameterException e)
{
throw new CMSException("invalid iv.", e);
}
}
}