nomulus/java/google/registry/rde/Ghostryde.java

// Copyright 2017 The Nomulus Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package google.registry.rde;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static google.registry.rde.RydeCompression.openCompressor;
import static google.registry.rde.RydeCompression.openDecompressor;
import static java.nio.charset.StandardCharsets.US_ASCII;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags.AES_128;
import static org.bouncycastle.jce.provider.BouncyCastleProvider.PROVIDER_NAME;
import static org.bouncycastle.openpgp.PGPLiteralData.BINARY;

import com.google.common.io.ByteStreams;
import com.google.common.io.Closer;
import google.registry.util.ImprovedInputStream;
import google.registry.util.ImprovedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.NoSuchAlgorithmException;
import java.security.ProviderException;
import java.security.SecureRandom;
import java.util.Optional;
import java.util.stream.Collectors;
import javax.annotation.CheckReturnValue;
import javax.annotation.Nullable;
import javax.annotation.WillNotClose;
import org.bouncycastle.openpgp.PGPEncryptedDataGenerator;
import org.bouncycastle.openpgp.PGPEncryptedDataList;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPLiteralData;
import org.bouncycastle.openpgp.PGPLiteralDataGenerator;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPPublicKeyEncryptedData;
import org.bouncycastle.openpgp.operator.bc.BcPublicKeyDataDecryptorFactory;
import org.bouncycastle.openpgp.operator.bc.BcPublicKeyKeyEncryptionMethodGenerator;
import org.bouncycastle.openpgp.operator.jcajce.JcePGPDataEncryptorBuilder;
import org.joda.time.DateTime;

/**
 * Utility class for reading and writing data in the ghostryde container format.
 *
 * <p>Whenever we stage sensitive data to cloud storage (like XML RDE deposit data), we
 * <a href="http://youtu.be/YPNJjL9iznY">GHOST RYDE IT</a> first to keep it safe from the prying
 * eyes of anyone with access to the <a href="https://cloud.google.com/console">Google Cloud
 * Console</a>.
 *
 * <p>The encryption is similar to the "regular" RyDE RDE deposit file encryption. The main
 * difference (and the reason we had to create a custom encryption) is that the RDE deposit has a
 * tar file in the encoding. A tar file needs to know its final size in the header, which means we
 * have to create the entire deposit before we can start encoding it.
 *
 * <p>Deposits are big, and there's no reason to hold it all in memory. Instead, save a "staging"
 * version encrypted with Ghostryde instead of "RyDE" (the RDE encryption/encoding), using the
 * "rde-staging" keys. We also remember the actual data size during the staging creation.
 *
 * <p>Then when we want to create the actual deposits, we decrypt the staging version, and using the
 * saved value for the data size we can encrypt with "RyDE" using the receiver key.
 *
 * <p>Here's how you write a file:
 *
 * <pre>   {@code
 * File in = new File("lol.txt");
 * File out = new File("lol.txt.ghostryde");
 * File lengthOut = new File("lol.length.ghostryde");
 * try (OutputStream output = new FileOutputStream(out);
 *     OutputStream lengthOutput = new FileOutputStream(lengthOut);
 *     OutputStream ghostrydeEncoder = Ghostryde.encoder(output, publicKey, lengthOut);
 *     InputStream input = new FileInputStream(in)) &lbrace;
 *   ByteStreams.copy(input, ghostrydeEncoder);
 * &rbrace;}</pre>
 *
 * <p>Here's how you read a file:
 *
 * <pre>   {@code
 * File in = new File("lol.txt.ghostryde");
 * File out = new File("lol.txt");
 * Ghostryde ghost = new Ghostryde(1024);
 * try (InputStream fileInput = new FileInputStream(in);
 *     InputStream ghostrydeDecoder = new Ghostryde.decoder(fileInput, privateKey);
 *     OutputStream fileOutput = new FileOutputStream(out)) &lbrace;
 *   ByteStreams.copy(ghostryderDecoder, fileOutput);
 * &rbrace;}</pre>
 *
 * <h2>Simple API</h2>
 *
 * <p>If you're writing test code or are certain your data can fit in memory, you might find these
 * static methods more convenient:
 *
 * <pre>   {@code
 * byte[] data = "hello kitty".getBytes(UTF_8);
 * byte[] blob = Ghostryde.encode(data, publicKey);
 * byte[] result = Ghostryde.decode(blob, privateKey);
 *
 * }</pre>
 *
 * <h2>GhostRYDE Format</h2>
 *
 * <p>A {@code .ghostryde} file is the exact same thing as a {@code .gpg} file, except the OpenPGP
 * message layers will always be present and in a specific order. You can analyse the layers on the
 * command-line using the {@code gpg --list-packets blah.ghostryde} command.
 *
 * <p>Ghostryde is different from RyDE in the sense that ghostryde is only used for <i>internal</i>
 * storage; whereas RyDE is meant to protect data being stored by a third-party.
 */
public final class Ghostryde {

  /** Size of the buffer used by the intermediate streams. */
  static final int BUFFER_SIZE = 64 * 1024;

  /**
   * Symmetric encryption cipher to use when creating ghostryde files.
   *
   * <p>We're going to use AES-128 just like {@link RydePgpEncryptionOutputStream}, although we
   * aren't forced to use this algorithm by the ICANN RFCs since this is an internal format.
   *
   * @see org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags
   */
  static final int CIPHER = AES_128;

  /**
   * Unlike {@link RydePgpEncryptionOutputStream}, we're going to enable the integrity packet
   * because it makes GnuPG happy. It's also probably necessary to prevent tampering since we
   * don't sign ghostryde files.
   */
  static final boolean USE_INTEGRITY_PACKET = true;

  /**
   * The source of random bits. You are strongly discouraged from changing this value because at
   * Google it's configured to use {@code /dev/&lbrace;,u&rbrace;random} in production and somehow
   * magically go fast and not drain entropy in the testing environment.
   *
   * @see SecureRandom#getInstance(String)
   */
  static final String RANDOM_SOURCE = "NativePRNG";

  /**
   * For backwards compatibility reasons, we wrap the data in a PGP file, which preserves the
   * original filename and modification time. However, these values are never used, so we just
   * set them to a constant value.
   */
  static final String INNER_FILENAME = "file.xml";
  static final DateTime INNER_MODIFICATION_TIME = DateTime.parse("2000-01-01TZ");

  /**
   * Creates a ghostryde file from an in-memory byte array.
   *
   * @throws PGPException
   * @throws IOException
   */
  public static byte[] encode(byte[] data, PGPPublicKey key)
      throws IOException, PGPException {
    checkNotNull(data, "data");
    checkArgument(key.isEncryptionKey(), "not an encryption key");
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    try (OutputStream encoder = encoder(output, key)) {
      encoder.write(data);
    }
    return output.toByteArray();
  }

  /**
   * Deciphers a ghostryde file from an in-memory byte array.
   *
   * @throws PGPException
   * @throws IOException
   */
  public static byte[] decode(byte[] data, PGPPrivateKey key)
      throws IOException, PGPException {
    checkNotNull(data, "data");
    ByteArrayInputStream dataStream = new ByteArrayInputStream(data);
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    try (InputStream ghostrydeDecoder = decoder(dataStream, key)) {
      ByteStreams.copy(ghostrydeDecoder, output);
    }
    return output.toByteArray();
  }

  /** Reads the value of a length stream - see {@link #encoder}. */
  public static long readLength(InputStream lengthStream) throws IOException {
    return Long.parseLong(new String(ByteStreams.toByteArray(lengthStream), UTF_8).trim());
  }

  /**
   * Creates a Ghostryde Encoder.
   *
   * <p>Optionally can also save the total length of the data written to an OutputStream.
   *
   * <p>This is necessary because the RyDE format uses a tar file which requires the total length in
   * the header. We don't want to have to decrypt the entire ghostryde file to determine the length,
   * so we just save it separately.
   *
   * @param output where to write the encrypted data
   * @param encryptionKey the encryption key to use
   * @param lengthOutput if not null - will save the total length of the data written to this
   *     output. See {@link #readLength}.
   */
  public static ImprovedOutputStream encoder(
      OutputStream output, PGPPublicKey encryptionKey, @Nullable OutputStream lengthOutput)
      throws IOException, PGPException {

    // We use a Closer to handle the stream .close, to make sure it's done correctly.
    Closer closer = Closer.create();
    OutputStream encryptionLayer = closer.register(openEncryptor(output, encryptionKey));
    OutputStream kompressor = closer.register(openCompressor(encryptionLayer));
    OutputStream fileLayer =
        closer.register(
            openPgpFileOutputStream(kompressor, INNER_FILENAME, INNER_MODIFICATION_TIME));

    return new ImprovedOutputStream("GhostrydeEncoder", fileLayer) {
      @Override
      public void onClose() throws IOException {
        // Close all the streams we opened
        closer.close();
        // Optionally also output the size of the encoded data - which is needed for the RyDE
        // encoding.
        if (lengthOutput != null) {
          lengthOutput.write(Long.toString(getBytesWritten()).getBytes(US_ASCII));
        }
      }
    };
  }

  /**
   * Creates a Ghostryde Encoder.
   *
   * @param output where to write the encrypted data
   * @param encryptionKey the encryption key to use
   */
  public static ImprovedOutputStream encoder(OutputStream output, PGPPublicKey encryptionKey)
      throws IOException, PGPException {
    return encoder(output, encryptionKey, null);
  }

  /**
   * Creates a Ghostryde decoder.
   *
   * @param input from where to read the encrypted data
   * @param decryptionKey the decryption key to use
   */
  public static ImprovedInputStream decoder(InputStream input, PGPPrivateKey decryptionKey)
      throws IOException, PGPException {

    // We use a Closer to handle the stream .close, to make sure it's done correctly.
    Closer closer = Closer.create();
    InputStream decryptionLayer = closer.register(openDecryptor(input, decryptionKey));
    InputStream decompressor = closer.register(openDecompressor(decryptionLayer));
    InputStream fileLayer = closer.register(openPgpFileInputStream(decompressor));

    return new ImprovedInputStream("GhostryderDecoder", fileLayer) {
      @Override
      public void onClose() throws IOException {
        // Close all the streams we opened
        closer.close();
      }
    };
  }

  private Ghostryde() {}

  /**
   * Opens a new encryptor (Writing Step 1/3)
   *
   * <p>This is the first step in creating a ghostryde file. After this method, you'll want to call
   * {@link #openCompressor}.
   *
   * <p>TODO(b/110465985): merge with the RyDE version.
   *
   * @param os is the upstream {@link OutputStream} to which the result is written.
   * @param publicKey is the public encryption key of the recipient.
   * @throws IOException
   * @throws PGPException
   */
  @CheckReturnValue
  private static ImprovedOutputStream openEncryptor(
      @WillNotClose OutputStream os, PGPPublicKey publicKey) throws IOException, PGPException {
    PGPEncryptedDataGenerator encryptor = new PGPEncryptedDataGenerator(
        new JcePGPDataEncryptorBuilder(CIPHER)
           .setWithIntegrityPacket(USE_INTEGRITY_PACKET)
           .setSecureRandom(getRandom())
           .setProvider(PROVIDER_NAME));
    encryptor.addMethod(new BcPublicKeyKeyEncryptionMethodGenerator(publicKey));
    return new ImprovedOutputStream(
        "GhostrydeEncryptor", encryptor.open(os, new byte[BUFFER_SIZE]));
  }

  /** Does stuff. */
  private static SecureRandom getRandom() {
    SecureRandom random;
    try {
      random = SecureRandom.getInstance(RANDOM_SOURCE);
    } catch (NoSuchAlgorithmException e) {
      throw new ProviderException(e);
    }
    return random;
  }

  /**
   * Opens an {@link OutputStream} to which the actual data should be written (Writing Step 3/3)
   *
   * <p>This is the third and final step in creating a ghostryde file. You'll want to write data to
   * the returned object.
   *
   * <p>TODO(b/110465985): merge with the RyDE version.
   *
   * @param os is the value returned by {@link #openCompressor}.
   * @param name is a filename for your data which gets written in the literal tag.
   * @param modified is a timestamp for your data which gets written to the literal tags.
   * @throws IOException
   */
  @CheckReturnValue
  private static ImprovedOutputStream openPgpFileOutputStream(
      @WillNotClose OutputStream os, String name, DateTime modified) throws IOException {
    return new ImprovedOutputStream(
        "GhostrydePgpFileOutput",
        new PGPLiteralDataGenerator()
            .open(os, BINARY, name, modified.toDate(), new byte[BUFFER_SIZE]));
  }

  /**
   * Opens a new decryptor (Reading Step 1/3)
   *
   * <p>This is the first step in opening a ghostryde file. After this method, you'll want to call
   * {@link #openDecompressor}.
   *
   * <p>Note: If {@link Ghostryde#USE_INTEGRITY_PACKET} is {@code true}, any ghostryde file without
   * an integrity packet will be considered invalid and an exception will be thrown.
   *
   * <p>TODO(b/110465985): merge with the RyDE version.
   *
   * @param input is an {@link InputStream} of the ghostryde file data.
   * @param privateKey is the private encryption key of the recipient (which is us!)
   * @throws IOException
   * @throws PGPException
   */
  @CheckReturnValue
  private static ImprovedInputStream openDecryptor(
      @WillNotClose InputStream input, PGPPrivateKey privateKey) throws IOException, PGPException {
    checkNotNull(privateKey, "privateKey");
    PGPEncryptedDataList ciphertextList =
        PgpUtils.readSinglePgpObject(input, PGPEncryptedDataList.class);
    // Go over all the possible decryption keys, and look for the one that has our key ID.
    Optional<PGPPublicKeyEncryptedData> cyphertext =
        PgpUtils.stream(ciphertextList, PGPPublicKeyEncryptedData.class)
            .filter(ciphertext -> ciphertext.getKeyID() == privateKey.getKeyID())
            .findAny();
    // If we can't find one with our key ID, then we can't decrypt the file!
    if (!cyphertext.isPresent()) {
      String keyIds =
          PgpUtils.stream(ciphertextList, PGPPublicKeyEncryptedData.class)
              .map(ciphertext -> Long.toHexString(ciphertext.getKeyID()))
              .collect(Collectors.joining(","));
      throw new PGPException(
          String.format(
              "Message was encrypted for keyids [%s] but ours is %x",
              keyIds, privateKey.getKeyID()));
    }

    // We want an input stream that also verifies ciphertext wasn't corrupted or tampered with when
    // the stream is closed.
    return new ImprovedInputStream(
        "GhostrydeDecryptor",
        cyphertext.get().getDataStream(new BcPublicKeyDataDecryptorFactory(privateKey))) {
      @Override
      protected void onClose() throws IOException {
        if (USE_INTEGRITY_PACKET) {
          try {
            if (!cyphertext.get().verify()) {
              throw new PGPException("ghostryde integrity check failed: possible tampering D:");
            }
          } catch (PGPException e) {
            throw new IllegalStateException(e);
          }
        }
      }
    };
  }

  /**
   * Opens a new decoder for reading the original contents (Reading Step 3/3)
   *
   * <p>This is the final step in reading a ghostryde file. After calling this method, you should
   * call the read methods on the returned {@link InputStream}.
   *
   * <p>TODO(b/110465985): merge with the RyDE version.
   *
   * @param input is the value returned by {@link #openDecompressor}.
   * @throws IOException
   * @throws PGPException
   */
  @CheckReturnValue
  private static ImprovedInputStream openPgpFileInputStream(@WillNotClose InputStream input)
      throws IOException, PGPException {
    PGPLiteralData literal = PgpUtils.readSinglePgpObject(input, PGPLiteralData.class);
    return new ImprovedInputStream("GhostrydePgpFileInputStream", literal.getDataStream());
  }
}