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The Bouncy Castle Java APIs for the OpenPGP Protocol. The APIs are designed primarily to be used in conjunction with the BC FIPS provider. The APIs may also be used with other providers although if being used in a FIPS context it is the responsibility of the user to ensure that any other providers used are FIPS certified and used appropriately.

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package org.bouncycastle.openpgp;

import java.io.InputStream;

import org.bouncycastle.bcpg.InputStreamPacket;
import org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags;
import org.bouncycastle.bcpg.SymmetricKeyEncSessionPacket;
import org.bouncycastle.openpgp.operator.PBEDataDecryptorFactory;
import org.bouncycastle.openpgp.operator.SessionKeyDataDecryptorFactory;
import org.bouncycastle.util.Arrays;

/**
 * A password based encryption object.
 * 
 * PBE encrypted data objects can be {@link #getDataStream(PBEDataDecryptorFactory) decrypted }
 * using a {@link PBEDataDecryptorFactory}.
 * 
 */
public class PGPPBEEncryptedData
    extends PGPSymmetricKeyEncryptedData
{
    SymmetricKeyEncSessionPacket keyData;

    /**
     * Construct a PBE encrypted data object.
     *
     * @param keyData the PBE key data packet associated with the encrypted data in the PGP object
     *                stream.
     * @param encData the encrypted data.
     */
    PGPPBEEncryptedData(
        SymmetricKeyEncSessionPacket keyData,
        InputStreamPacket encData)
    {
        super(encData);

        this.keyData = keyData;
    }

    public int getVersion()
    {
        return keyData.getVersion();
    }

    public int getAlgorithm()
    {
        return keyData.getEncAlgorithm();
    }

    /**
     * Return the symmetric key algorithm required to decrypt the data protected by this object.
     *
     * @param dataDecryptorFactory decryptor factory to use to recover the session data.
     * @return the identifier of the {@link SymmetricKeyAlgorithmTags encryption algorithm} used to
     * encrypt this object.
     * @throws PGPException if the session data cannot be recovered.
     */
    public int getSymmetricAlgorithm(
        PBEDataDecryptorFactory dataDecryptorFactory)
        throws PGPException
    {
        byte[] key = dataDecryptorFactory.makeKeyFromPassPhrase(keyData.getEncAlgorithm(), keyData.getS2K());
        byte[] sessionData = dataDecryptorFactory.recoverSessionData(keyData.getEncAlgorithm(), key, keyData.getSecKeyData());

        return sessionData[0];
    }

    /**
     * Return the symmetric session key required to decrypt the data protected by this object.
     *
     * @param dataDecryptorFactory decryptor factory used to recover the session data.
     * @return session key
     * @throws PGPException if the session data cannot be recovered
     */
    public PGPSessionKey getSessionKey(PBEDataDecryptorFactory dataDecryptorFactory)
        throws PGPException
    {
        byte[] key = dataDecryptorFactory.makeKeyFromPassPhrase(keyData.getEncAlgorithm(), keyData.getS2K());
        byte[] sessionData = dataDecryptorFactory.recoverSessionData(keyData.getEncAlgorithm(), key, keyData.getSecKeyData());

        return new PGPSessionKey(sessionData[0] & 0xff, Arrays.copyOfRange(sessionData, 1, sessionData.length));
    }

    /**
     * Open an input stream which will provide the decrypted data protected by this object.
     *
     * @param dataDecryptorFactory decryptor factory to use to recover the session data and provide
     *                             the stream.
     * @return the resulting decrypted input stream, probably containing a sequence of PGP data
     * objects.
     * @throws PGPException if the session data cannot be recovered or the stream cannot be created.
     */
    public InputStream getDataStream(
        PBEDataDecryptorFactory dataDecryptorFactory)
        throws PGPException
    {
        try
        {
            PGPSessionKey sessionKey = getSessionKey(dataDecryptorFactory);

            encStream = createDecryptionStream(dataDecryptorFactory, sessionKey);

            return encStream;
        }
        catch (PGPException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new PGPException("Exception creating cipher", e);
        }
    }

    /**
     * @deprecated will be removed in 1.74, use PGPEncryptedDataList.extractSessionKeyEncryptedData() and then apply the dataDecryptorFactory.
     */
    public InputStream getDataStream(
        SessionKeyDataDecryptorFactory dataDecryptorFactory)
        throws PGPException
    {
        try
        {
            PGPSessionKey sessionKey = dataDecryptorFactory.getSessionKey();

            encStream = createDecryptionStream(dataDecryptorFactory, sessionKey);

            return encStream;
        }
        catch (PGPException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new PGPException("Exception creating cipher", e);
        }
    }
}