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KeyAgreeRecipientInformation.javaAPI DocBouncy Castle Crypto API 1.41 (Java 1.5)4902Wed Oct 01 10:55:30 BST 2008org.bouncycastle.cms

KeyAgreeRecipientInformation

public class KeyAgreeRecipientInformation extends RecipientInformation
the RecipientInfo class for a recipient who has been sent a message encrypted using key agreement.

Fields Summary
private org.bouncycastle.asn1.cms.KeyAgreeRecipientInfo
_info
private org.bouncycastle.asn1.ASN1OctetString
_encryptedKey
Constructors Summary
public KeyAgreeRecipientInformation(org.bouncycastle.asn1.cms.KeyAgreeRecipientInfo info, org.bouncycastle.asn1.x509.AlgorithmIdentifier encAlg, InputStream data)

        super(encAlg, AlgorithmIdentifier.getInstance(info.getKeyEncryptionAlgorithm()), data);

        _info = info;
//        _encAlg = encAlg;

        try
        {
            ASN1Sequence s = _info.getRecipientEncryptedKeys();
            RecipientEncryptedKey id = RecipientEncryptedKey.getInstance(s.getObjectAt(0));

            IssuerAndSerialNumber iAnds = id.getIdentifier().getIssuerAndSerialNumber();

            _rid = new RecipientId();
            _rid.setIssuer(iAnds.getName().getEncoded());
            _rid.setSerialNumber(iAnds.getSerialNumber().getValue());

            _encryptedKey = id.getEncryptedKey();
        }
        catch (IOException e)
        {
            throw new IllegalArgumentException("invalid rid in KeyAgreeRecipientInformation");
        }
Methods Summary
public CMSTypedStreamgetContentStream(java.security.Key key, java.lang.String prov)
decrypt the content and return an input stream.

        return getContentStream(key, CMSUtils.getProvider(prov));
public CMSTypedStreamgetContentStream(java.security.Key key, java.security.Provider prov)

        try
        {
            OriginatorPublicKey origK = _info.getOriginator().getOriginatorKey();
            PrivateKeyInfo privInfo = PrivateKeyInfo.getInstance(ASN1Object.fromByteArray(key.getEncoded()));
            SubjectPublicKeyInfo pubInfo = new SubjectPublicKeyInfo(privInfo.getAlgorithmId(), origK.getPublicKey().getBytes());
            X509EncodedKeySpec pubSpec = new X509EncodedKeySpec(pubInfo.getEncoded());
            KeyFactory fact = KeyFactory.getInstance(_keyEncAlg.getObjectId().getId(), prov);
            KeyAgreement agreement = KeyAgreement.getInstance(_keyEncAlg.getObjectId().getId(), prov);
                            
            agreement.init(key);

            agreement.doPhase(fact.generatePublic(pubSpec), true);

            String wrapAlg = DERObjectIdentifier.getInstance(
                                   ASN1Sequence.getInstance(_keyEncAlg.getParameters()).getObjectAt(0)).getId();

            Key wKey = agreement.generateSecret(wrapAlg);

            Cipher keyCipher = Cipher.getInstance(wrapAlg, prov);

            keyCipher.init(Cipher.UNWRAP_MODE, wKey);

            AlgorithmIdentifier aid = _encAlg;
            String              alg = aid.getObjectId().getId();

            byte[]              encryptedKey = _encryptedKey.getOctets();
            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 (InvalidKeySpecException e)
        {
            throw new CMSException("originator key spec invalid.", e);
        }
        catch (NoSuchPaddingException e)
        {
            throw new CMSException("required padding not supported.", e);
        }
        catch (Exception e)
        {
            throw new CMSException("originator key invalid.", e);
        }