org.bouncycastle.openpgp.PGPPBEEncryptedData Maven / Gradle / Ivy

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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.EOFException;
import java.io.InputStream;

import org.bouncycastle.bcpg.BCPGInputStream;
import org.bouncycastle.bcpg.InputStreamPacket;
import org.bouncycastle.bcpg.SymmetricEncIntegrityPacket;
import org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags;
import org.bouncycastle.bcpg.SymmetricKeyEncSessionPacket;
import org.bouncycastle.openpgp.operator.PBEDataDecryptorFactory;
import org.bouncycastle.openpgp.operator.PGPDataDecryptor;
import org.bouncycastle.util.io.TeeInputStream;

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

    /**
     * Construct a PBE encryped 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;
    }

    /**
     * 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];
    }

    /**
     * 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
        {
            int          keyAlgorithm = keyData.getEncAlgorithm();
            byte[]       key = dataDecryptorFactory.makeKeyFromPassPhrase(keyAlgorithm, keyData.getS2K());
            boolean      withIntegrityPacket = encData instanceof SymmetricEncIntegrityPacket;

            byte[]       sessionData = dataDecryptorFactory.recoverSessionData(keyData.getEncAlgorithm(), key, keyData.getSecKeyData());
            byte[]       sessionKey = new byte[sessionData.length - 1];

            System.arraycopy(sessionData, 1, sessionKey, 0, sessionKey.length);

            PGPDataDecryptor dataDecryptor = dataDecryptorFactory.createDataDecryptor(withIntegrityPacket, sessionData[0] & 0xff, sessionKey);

            encStream = new BCPGInputStream(dataDecryptor.getInputStream(encData.getInputStream()));

            if (withIntegrityPacket)
            {
                truncStream = new TruncatedStream(encStream);

                integrityCalculator = dataDecryptor.getIntegrityCalculator();

                encStream = new TeeInputStream(truncStream, integrityCalculator.getOutputStream());
            }

            byte[] iv = new byte[dataDecryptor.getBlockSize()];
            for (int i = 0; i != iv.length; i++)
            {
                int    ch = encStream.read();

                if (ch < 0)
                {
                    throw new EOFException("unexpected end of stream.");
                }

                iv[i] = (byte)ch;
            }

            int    v1 = encStream.read();
            int    v2 = encStream.read();

            if (v1 < 0 || v2 < 0)
            {
                throw new EOFException("unexpected end of stream.");
            }


            // Note: the oracle attack on "quick check" bytes is not deemed
            // a security risk for PBE (see PGPPublicKeyEncryptedData)

            boolean repeatCheckPassed = iv[iv.length - 2] == (byte) v1
                    && iv[iv.length - 1] == (byte) v2;

            // Note: some versions of PGP appear to produce 0 for the extra
            // bytes rather than repeating the two previous bytes
            boolean zeroesCheckPassed = v1 == 0 && v2 == 0;

            if (!repeatCheckPassed && !zeroesCheckPassed)
            {
                throw new PGPDataValidationException("data check failed.");
            }

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