org.bouncycastle.openpgp.PGPPublicKeyEncryptedData 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.PublicKeyEncSessionPacket;
import org.bouncycastle.bcpg.SymmetricEncIntegrityPacket;
import org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags;
import org.bouncycastle.openpgp.operator.PGPDataDecryptor;
import org.bouncycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
import org.bouncycastle.util.io.TeeInputStream;

/**
 * A public key encrypted data object.
 */
public class PGPPublicKeyEncryptedData
    extends PGPEncryptedData
{
    PublicKeyEncSessionPacket        keyData;

    PGPPublicKeyEncryptedData(
        PublicKeyEncSessionPacket    keyData,
        InputStreamPacket            encData)
    {
        super(encData);

        this.keyData = keyData;
    }

    private boolean confirmCheckSum(
        byte[]    sessionInfo)
    {
        int    check = 0;

        for (int i = 1; i != sessionInfo.length - 2; i++)
        {
            check += sessionInfo[i] & 0xff;
        }

        return (sessionInfo[sessionInfo.length - 2] == (byte)(check >> 8))
                    && (sessionInfo[sessionInfo.length - 1] == (byte)(check));
    }

    /**
     * Return the keyID for the key used to encrypt the data.
     *
     * @return long
     */
    public long getKeyID()
    {
        return keyData.getKeyID();
    }

    /**
     * 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(
        PublicKeyDataDecryptorFactory dataDecryptorFactory)
        throws PGPException
    {
        byte[] plain = dataDecryptorFactory.recoverSessionData(keyData.getAlgorithm(), keyData.getEncSessionKey());

        return plain[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 input stream
     * @throws PGPException  if the session data cannot be recovered or the stream cannot be created.
     */
    public InputStream getDataStream(
        PublicKeyDataDecryptorFactory dataDecryptorFactory)
        throws PGPException
    {
        byte[] sessionData = dataDecryptorFactory.recoverSessionData(keyData.getAlgorithm(), keyData.getEncSessionKey());

        if (!confirmCheckSum(sessionData))
        {
            throw new PGPKeyValidationException("key checksum failed");
        }

        if (sessionData[0] != SymmetricKeyAlgorithmTags.NULL)
        {
            try
            {
                boolean      withIntegrityPacket = encData instanceof SymmetricEncIntegrityPacket;
                byte[]       sessionKey = new byte[sessionData.length - 3];

                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.");
                }

                //
                // some versions of PGP appear to produce 0 for the extra
                // bytes rather than repeating the two previous bytes
                //
                /*
                             * Commented out in the light of the oracle attack.
                            if (iv[iv.length - 2] != (byte)v1 && v1 != 0)
                            {
                                throw new PGPDataValidationException("data check failed.");
                            }

                            if (iv[iv.length - 1] != (byte)v2 && v2 != 0)
                            {
                                throw new PGPDataValidationException("data check failed.");
                            }
                            */

                return encStream;
            }
            catch (PGPException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new PGPException("Exception starting decryption", e);
            }
        }
        else
        {
            return encData.getInputStream();
        }
    }
}