/**
 * Builds a PGPSignatureGenerator for the specified key and content.
 */
protected PGPSignatureGenerator buildSigner(Key key, FileMetadata meta)
        throws PGPException {
    Subkey subkey = key.getSigning();

    log.info("using signing key {}", subkey);

    PGPContentSignerBuilder builder = buildSignerBuilder(
        subkey.getPublicKey().getAlgorithm(),
        signingAlgorithm.ordinal()
    );

    PGPSignatureGenerator generator = new PGPSignatureGenerator(builder);
    generator.init(meta.getSignatureType(), subkey.getPrivateKey());

    String uid = key.getSigningUid();
    if (!Util.isEmpty(uid)) {
        log.debug("using signing uid {}", uid);

        PGPSignatureSubpacketGenerator signer =
            new PGPSignatureSubpacketGenerator();
        signer.setSignerUserID(false, uid);
        generator.setHashedSubpackets(signer.generate());
    }

    return generator;
}
 

public static byte[] signAndEncrypt( final byte[] message, final PGPSecretKey secretKey, final String secretPwd,
                                     final PGPPublicKey publicKey, final boolean armored ) throws PGPException
{
    try
    {
        final ByteArrayOutputStream out = new ByteArrayOutputStream();
        final PGPEncryptedDataGenerator encryptedDataGenerator = new PGPEncryptedDataGenerator(
                new JcePGPDataEncryptorBuilder( SymmetricKeyAlgorithmTags.AES_256 ).setWithIntegrityPacket( true )
                                                                                   .setSecureRandom(
                                                                                           new SecureRandom() )
                                                                                   .setProvider( provider ) );

        encryptedDataGenerator.addMethod(
                new JcePublicKeyKeyEncryptionMethodGenerator( publicKey ).setSecureRandom( new SecureRandom() )
                                                                         .setProvider( provider ) );

        final OutputStream theOut = armored ? new ArmoredOutputStream( out ) : out;
        final OutputStream encryptedOut = encryptedDataGenerator.open( theOut, new byte[4096] );

        final PGPCompressedDataGenerator compressedDataGenerator =
                new PGPCompressedDataGenerator( CompressionAlgorithmTags.ZIP );
        final OutputStream compressedOut = compressedDataGenerator.open( encryptedOut, new byte[4096] );
        final PGPPrivateKey privateKey = secretKey.extractPrivateKey(
                new JcePBESecretKeyDecryptorBuilder().setProvider( provider ).build( secretPwd.toCharArray() ) );
        final PGPSignatureGenerator signatureGenerator = new PGPSignatureGenerator(
                new JcaPGPContentSignerBuilder( secretKey.getPublicKey().getAlgorithm(), HashAlgorithmTags.SHA1 )
                        .setProvider( provider ) );
        signatureGenerator.init( PGPSignature.BINARY_DOCUMENT, privateKey );
        final Iterator<?> it = secretKey.getPublicKey().getUserIDs();
        if ( it.hasNext() )
        {
            final PGPSignatureSubpacketGenerator spGen = new PGPSignatureSubpacketGenerator();
            spGen.setSignerUserID( false, ( String ) it.next() );
            signatureGenerator.setHashedSubpackets( spGen.generate() );
        }
        signatureGenerator.generateOnePassVersion( false ).encode( compressedOut );
        final PGPLiteralDataGenerator literalDataGenerator = new PGPLiteralDataGenerator();
        final OutputStream literalOut = literalDataGenerator
                .open( compressedOut, PGPLiteralData.BINARY, "filename", new Date(), new byte[4096] );
        final InputStream in = new ByteArrayInputStream( message );
        final byte[] buf = new byte[4096];
        for ( int len; ( len = in.read( buf ) ) > 0; )
        {
            literalOut.write( buf, 0, len );
            signatureGenerator.update( buf, 0, len );
        }
        in.close();
        literalDataGenerator.close();
        signatureGenerator.generate().encode( compressedOut );
        compressedDataGenerator.close();
        encryptedDataGenerator.close();
        theOut.close();
        return out.toByteArray();
    }
    catch ( Exception e )
    {
        throw new PGPException( "Error in signAndEncrypt", e );
    }
}
 

public byte[] signInline(String input) throws IOException, PGPException {
  PGPSecretKey signKey = readSecretKey();
  PGPPrivateKey privKey = signKey.extractPrivateKey(
      new JcePBESecretKeyDecryptorBuilder().setProvider("BC").build(config.passphrase.toCharArray()));
  PGPSignatureGenerator sigGenerator = new PGPSignatureGenerator(
      new JcaPGPContentSignerBuilder(signKey.getPublicKey().getAlgorithm(), PGPUtil.SHA256).setProvider("BC"));
  sigGenerator.init(PGPSignature.CANONICAL_TEXT_DOCUMENT, privKey);

  @SuppressWarnings("unchecked")
  Iterator<String> userIds = signKey.getUserIDs();
  if (userIds.hasNext()) {
    PGPSignatureSubpacketGenerator sigSubpacketGenerator = new PGPSignatureSubpacketGenerator();
    sigSubpacketGenerator.setSignerUserID(false, userIds.next());
    sigGenerator.setHashedSubpackets(sigSubpacketGenerator.generate());
  }

  String[] lines = input.split("\r?\n");
  ByteArrayOutputStream buffer = new ByteArrayOutputStream();
  try (ArmoredOutputStream aOut = new ArmoredOutputStream(buffer)) {
    aOut.beginClearText(PGPUtil.SHA256);

    boolean firstLine = true;
    for (String line : lines) {
      String sigLine = (firstLine ? "" : "\r\n") + line.replaceAll("\\s*$", "");
      sigGenerator.update(sigLine.getBytes(Charsets.UTF_8));
      aOut.write((line + "\n").getBytes(Charsets.UTF_8));
      firstLine = false;
    }
    aOut.endClearText();

    BCPGOutputStream bOut = new BCPGOutputStream(aOut);
    sigGenerator.generate().encode(bOut);
  }
  return buffer.toByteArray();
}
 

public byte[] signInline(final String input) throws IOException {
  ByteArrayOutputStream buffer = new ByteArrayOutputStream();
  try {
    PGPSecretKey signKey = readSecretKey();
    PGPPrivateKey privKey = signKey.extractPrivateKey(
        new JcePBESecretKeyDecryptorBuilder().setProvider("BC").build(config.passphrase.toCharArray()));
    PGPSignatureGenerator sigGenerator = new PGPSignatureGenerator(
        new JcaPGPContentSignerBuilder(signKey.getPublicKey().getAlgorithm(), PGPUtil.SHA256).setProvider("BC"));
    sigGenerator.init(PGPSignature.CANONICAL_TEXT_DOCUMENT, privKey);

    Iterator<String> userIds = signKey.getUserIDs();
    if (userIds.hasNext()) {
      PGPSignatureSubpacketGenerator sigSubpacketGenerator = new PGPSignatureSubpacketGenerator();
      sigSubpacketGenerator.setSignerUserID(false, userIds.next());
      sigGenerator.setHashedSubpackets(sigSubpacketGenerator.generate());
    }

    String[] lines = input.split("\r?\n");
    try (ArmoredOutputStream aOut = new ArmoredOutputStream(buffer)) {
      aOut.beginClearText(PGPUtil.SHA256);

      boolean firstLine = true;
      for (String line : lines) {
        String sigLine = (firstLine ? "" : "\r\n") + line.replaceAll("\\s*$", "");
        sigGenerator.update(sigLine.getBytes(Charsets.UTF_8));
        aOut.write((line + "\n").getBytes(Charsets.UTF_8));
        firstLine = false;
      }
      aOut.endClearText();

      BCPGOutputStream bOut = new BCPGOutputStream(aOut);
      sigGenerator.generate().encode(bOut);
    }
  }
  catch (PGPException ex) {
    throw new RuntimeException(ex);
  }
  return buffer.toByteArray();
}
 

private static PGPKeyRingGenerator generateKeyRingGenerator( String id, char[] pass, int s2kcount, int keySize,
                                                             KeyPair keyPair ) throws PGPException
{
    // This object generates individual key-pairs.
    RSAKeyPairGenerator kpg = new RSAKeyPairGenerator();

    // Boilerplate RSA parameters, no need to change anything
    // except for the RSA key-size (2048). You can use whatever
    // key-size makes sense for you -- 4096, etc.
    kpg.init( new RSAKeyGenerationParameters( BigInteger.valueOf( 0x10001 ), new SecureRandom(), keySize, 12 ) );

    // First create the master (signing) key with the generator.
    PGPKeyPair rsakp_sign = new BcPGPKeyPair( PGPPublicKey.RSA_GENERAL, kpg.generateKeyPair(), new Date() );
    // Then an encryption subkey.
    PGPKeyPair rsakp_enc = new BcPGPKeyPair( PGPPublicKey.RSA_GENERAL, kpg.generateKeyPair(), new Date() );

    keyPair.setPrimaryKeyId( Long.toHexString( rsakp_sign.getKeyID() ) );
    keyPair.setPrimaryKeyFingerprint( BytesToHex( rsakp_sign.getPublicKey().getFingerprint() ) );
    keyPair.setSubKeyId( Long.toHexString( rsakp_enc.getKeyID() ) );
    keyPair.setSubKeyFingerprint( BytesToHex( rsakp_enc.getPublicKey().getFingerprint() ) );

    // Add a self-signature on the id
    PGPSignatureSubpacketGenerator signhashgen = new PGPSignatureSubpacketGenerator();

    // Add signed metadata on the signature.
    // 1) Declare its purpose
    signhashgen.setKeyFlags( false, KeyFlags.SIGN_DATA | KeyFlags.CERTIFY_OTHER );
    // 2) Set preferences for secondary crypto algorithms to use
    //    when sending messages to this key.
    signhashgen.setPreferredSymmetricAlgorithms( false, new int[] {
            SymmetricKeyAlgorithmTags.AES_256, SymmetricKeyAlgorithmTags.AES_192, SymmetricKeyAlgorithmTags.AES_128,
            SymmetricKeyAlgorithmTags.CAST5, SymmetricKeyAlgorithmTags.TRIPLE_DES
    } );
    signhashgen.setPreferredHashAlgorithms( false, new int[] {
            HashAlgorithmTags.SHA256, HashAlgorithmTags.SHA1, HashAlgorithmTags.SHA384, HashAlgorithmTags.SHA512,
            HashAlgorithmTags.SHA224,
    } );
    signhashgen.setPreferredCompressionAlgorithms( false, new int[] {
            CompressionAlgorithmTags.ZLIB, CompressionAlgorithmTags.BZIP2, CompressionAlgorithmTags.ZIP
    } );
    // 3) Request senders add additional checksums to the
    //    message (useful when verifying unsigned messages.)
    signhashgen.setFeature( false, Features.FEATURE_MODIFICATION_DETECTION );

    // Create a signature on the encryption subkey.
    PGPSignatureSubpacketGenerator enchashgen = new PGPSignatureSubpacketGenerator();
    // Add metadata to declare its purpose
    enchashgen.setKeyFlags( false, KeyFlags.ENCRYPT_COMMS | KeyFlags.ENCRYPT_STORAGE );

    // Objects used to encrypt the secret key.
    PGPDigestCalculator sha1Calc = new BcPGPDigestCalculatorProvider().get( HashAlgorithmTags.SHA1 );

    // bcpg 1.48 exposes this API that includes s2kcount. Earlier
    // versions use a default of 0x60.
    PBESecretKeyEncryptor pske =
            ( new BcPBESecretKeyEncryptorBuilder( PGPEncryptedData.CAST5, sha1Calc, s2kcount ) ).build( pass );
    // Finally, create the keyring itself. The constructor
    // takes parameters that allow it to generate the self
    // signature.
    PGPKeyRingGenerator keyRingGen =
            new PGPKeyRingGenerator( PGPSignature.POSITIVE_CERTIFICATION, rsakp_sign, id, sha1Calc,
                    signhashgen.generate(), null,
                    new BcPGPContentSignerBuilder( rsakp_sign.getPublicKey().getAlgorithm(),
                            HashAlgorithmTags.SHA1 ), pske );

    // Add our encryption subkey, together with its signature.
    keyRingGen.addSubKey( rsakp_enc, enchashgen.generate(), null );
    return keyRingGen;
}
 

public static byte[] sign( byte[] message, PGPSecretKey secretKey, String secretPwd, boolean armor )
        throws PGPException
{
    try
    {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        OutputStream theOut = armor ? new ArmoredOutputStream( out ) : out;

        PGPPrivateKey pgpPrivKey = secretKey.extractPrivateKey(
                new JcePBESecretKeyDecryptorBuilder().setProvider( provider ).build( secretPwd.toCharArray() ) );
        PGPSignatureGenerator sGen = new PGPSignatureGenerator(
                new JcaPGPContentSignerBuilder( secretKey.getPublicKey().getAlgorithm(), PGPUtil.SHA1 )
                        .setProvider( provider ) );

        sGen.init( PGPSignature.BINARY_DOCUMENT, pgpPrivKey );

        Iterator it = secretKey.getPublicKey().getUserIDs();
        if ( it.hasNext() )
        {
            PGPSignatureSubpacketGenerator spGen = new PGPSignatureSubpacketGenerator();

            spGen.setSignerUserID( false, ( String ) it.next() );
            sGen.setHashedSubpackets( spGen.generate() );
        }

        PGPCompressedDataGenerator cGen = new PGPCompressedDataGenerator( PGPCompressedData.ZLIB );

        BCPGOutputStream bOut = new BCPGOutputStream( cGen.open( theOut ) );

        sGen.generateOnePassVersion( false ).encode( bOut );

        PGPLiteralDataGenerator lGen = new PGPLiteralDataGenerator();
        OutputStream lOut =
                lGen.open( bOut, PGPLiteralData.BINARY, "filename", new Date(), new byte[4096] );         //
        InputStream fIn = new ByteArrayInputStream( message );
        int ch;

        while ( ( ch = fIn.read() ) >= 0 )
        {
            lOut.write( ch );
            sGen.update( ( byte ) ch );
        }

        lGen.close();

        sGen.generate().encode( bOut );

        cGen.close();

        theOut.close();

        return out.toByteArray();
    }
    catch ( Exception e )
    {
        throw new PGPException( "Error in sign", e );
    }
}
 

public static byte[] clearSign( byte[] message, PGPSecretKey pgpSecKey, char[] pass, String digestName )
        throws IOException, PGPException, SignatureException
{
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int digest;

    if ( "SHA256".equals( digestName ) )
    {
        digest = PGPUtil.SHA256;
    }
    else if ( "SHA384".equals( digestName ) )
    {
        digest = PGPUtil.SHA384;
    }
    else if ( "SHA512".equals( digestName ) )
    {
        digest = PGPUtil.SHA512;
    }
    else if ( "MD5".equals( digestName ) )
    {
        digest = PGPUtil.MD5;
    }
    else if ( "RIPEMD160".equals( digestName ) )
    {
        digest = PGPUtil.RIPEMD160;
    }
    else
    {
        digest = PGPUtil.SHA1;
    }

    PGPPrivateKey pgpPrivKey =
            pgpSecKey.extractPrivateKey( new JcePBESecretKeyDecryptorBuilder().setProvider( "BC" ).build( pass ) );
    PGPSignatureGenerator sGen = new PGPSignatureGenerator(
            new JcaPGPContentSignerBuilder( pgpSecKey.getPublicKey().getAlgorithm(), digest ).setProvider( "BC" ) );
    PGPSignatureSubpacketGenerator spGen = new PGPSignatureSubpacketGenerator();

    sGen.init( PGPSignature.CANONICAL_TEXT_DOCUMENT, pgpPrivKey );

    Iterator it = pgpSecKey.getPublicKey().getUserIDs();
    if ( it.hasNext() )
    {
        spGen.setSignerUserID( false, ( String ) it.next() );
        sGen.setHashedSubpackets( spGen.generate() );
    }

    InputStream fIn = new ByteArrayInputStream( message );
    ArmoredOutputStream aOut = new ArmoredOutputStream( out );

    aOut.beginClearText( digest );

    //
    // note the last \n/\r/\r\n in the file is ignored
    //
    ByteArrayOutputStream lineOut = new ByteArrayOutputStream();
    int lookAhead = readInputLine( lineOut, fIn );

    processLine( aOut, sGen, lineOut.toByteArray() );

    if ( lookAhead != -1 )
    {
        do
        {
            lookAhead = readInputLine( lineOut, lookAhead, fIn );

            sGen.update( ( byte ) '\r' );
            sGen.update( ( byte ) '\n' );

            processLine( aOut, sGen, lineOut.toByteArray() );
        }
        while ( lookAhead != -1 );
    }

    fIn.close();

    aOut.endClearText();

    BCPGOutputStream bOut = new BCPGOutputStream( aOut );

    sGen.generate().encode( bOut );

    aOut.close();

    return out.toByteArray();
}
 

/**
 * Encrypt, sign and write input stream data to output stream.
 * Input and output stream are closed.
 */
private static void encryptAndSign(
        InputStream plainInput, OutputStream encryptedOutput,
        PersonalKey myKey, List<PGPUtils.PGPCoderKey> receiverKeys)
        throws IOException, PGPException {

    // setup data encryptor & generator
    BcPGPDataEncryptorBuilder encryptor = new BcPGPDataEncryptorBuilder(PGPEncryptedData.AES_192);
    encryptor.setWithIntegrityPacket(true);
    encryptor.setSecureRandom(new SecureRandom());

    // add public key recipients
    PGPEncryptedDataGenerator encGen = new PGPEncryptedDataGenerator(encryptor);
    receiverKeys.forEach(key ->
        encGen.addMethod(new BcPublicKeyKeyEncryptionMethodGenerator(key.encryptKey)));

    OutputStream encryptedOut = encGen.open(encryptedOutput, new byte[BUFFER_SIZE]);

    // setup compressed data generator
    PGPCompressedDataGenerator compGen = new PGPCompressedDataGenerator(PGPCompressedData.ZIP);
    OutputStream compressedOut = compGen.open(encryptedOut, new byte[BUFFER_SIZE]);

    // setup signature generator
    int algo = myKey.getSigningAlgorithm();
    PGPSignatureGenerator sigGen = new PGPSignatureGenerator(
            new BcPGPContentSignerBuilder(algo, HashAlgorithmTags.SHA256));
    sigGen.init(PGPSignature.BINARY_DOCUMENT, myKey.getPrivateSigningKey());

    PGPSignatureSubpacketGenerator spGen = new PGPSignatureSubpacketGenerator();
    spGen.setSignerUserID(false, myKey.getUserId());
    sigGen.setUnhashedSubpackets(spGen.generate());

    sigGen.generateOnePassVersion(false).encode(compressedOut);

    // Initialize literal data generator
    PGPLiteralDataGenerator literalGen = new PGPLiteralDataGenerator();
    OutputStream literalOut = literalGen.open(
        compressedOut,
        PGPLiteralData.BINARY,
        "",
        new Date(),
        new byte[BUFFER_SIZE]);

    // read the "in" stream, compress, encrypt and write to the "out" stream
    // this must be done if clear data is bigger than the buffer size
    // but there are other ways to optimize...
    byte[] buf = new byte[BUFFER_SIZE];
    int len;
    while ((len = plainInput.read(buf)) > 0) {
        literalOut.write(buf, 0, len);
        sigGen.update(buf, 0, len);
    }

    literalGen.close();

    // generate the signature, compress, encrypt and write to the "out" stream
    sigGen.generate().encode(compressedOut);
    compGen.close();
    encGen.close();
}
 

/**
 * Add user ID to signature file.
 *
 * <p>This adds information about the identity of the signer to the signature file. It's not
 * required, but I'm guessing it could be a lifesaver if somewhere down the road, people lose
 * track of the public keys and need to figure out how to verify a couple blobs. This would at
 * least tell them which key to download from the MIT keyserver.
 *
 * <p>But the main reason why I'm using this is because I copied it from the code of another
 * googler who was also uncertain about the precise reason why it's needed.
 */
private static void addUserInfoToSignature(PGPPublicKey publicKey, PGPSignatureGenerator signer) {
  Iterator<String> uidIter = publicKey.getUserIDs();
  if (uidIter.hasNext()) {
    PGPSignatureSubpacketGenerator spg = new PGPSignatureSubpacketGenerator();
    spg.setSignerUserID(false, uidIter.next());
    signer.setHashedSubpackets(spg.generate());
  }
}
 

/**
 * Add user ID to signature file.
 *
 * <p>This adds information about the identity of the signer to the signature file. It's not
 * required, but I'm guessing it could be a lifesaver if somewhere down the road, people lose
 * track of the public keys and need to figure out how to verify a couple blobs. This would at
 * least tell them which key to download from the MIT keyserver.
 *
 * <p>But the main reason why I'm using this is because I copied it from the code of another
 * Googler who was also uncertain about the precise reason why it's needed.
 */
private void addUserInfoToSignature(PGPPublicKey publicKey, PGPSignatureGenerator signer) {
  Iterator<String> uidIter = publicKey.getUserIDs();
  if (uidIter.hasNext()) {
    PGPSignatureSubpacketGenerator spg = new PGPSignatureSubpacketGenerator();
    spg.setSignerUserID(false, uidIter.next());
    signer.setHashedSubpackets(spg.generate());
  }
}