Zip byte array with password

Question

I have pdf file in byte[] array. I want to compress it and encrypt with password. I don't want to create any temp files. But libraries like zip4j, winzipaes doesn't support it. They accept only File objects.

EDIT: code for simple zip:

public static byte[] zipBytes(String filename, byte[] input) throws IOException {

ByteArrayOutputStream baos = new ByteArrayOutputStream();

ZipOutputStream zos = new ZipOutputStream(baos);

ZipEntry entry = new ZipEntry(filename);

entry.setSize(input.length);

zos.putNextEntry(entry);

zos.write(input);

zos.closeEntry();

zos.close();

return baos.toByteArray();}

How add encryption and password?

Answer 1

A little late but hope this little snippet helps someone else. This is for zip4j on Java 7

private byte[] compressFileByZip(byte[] fileBytes, String filenameInZip, String zipFilePassword) throws ZipException {

  // Zip into a ByteArrayOutputStream
  ByteArrayOutputStream baos = new ByteArrayOutputStream();
  try(ZipOutputStream zos = new ZipOutputStream(baos)) {

    ZipParameters zipParameters = new ZipParameters();
    zipParameters.setCompressionMethod(Zip4jConstants.COMP_DEFLATE);
    zipParameters.setCompressionLevel(Zip4jConstants.DEFLATE_LEVEL_NORMAL);
    zipParameters.setSourceExternalStream(true);
    zipParameters.setFileNameInZip(filenameInZip);

    // Set the encryption method to AES Zip Encryption
    zipParameters.setEncryptFiles(true);
    zipParameters.setEncryptionMethod(Zip4jConstants.ENC_METHOD_AES);
    zipParameters.setAesKeyStrength(Zip4jConstants.AES_STRENGTH_256);
    zipParameters.setPassword(zipFilePassword);

    // Zip, flush and clean up
    zos.putNextEntry(null, zipParameters);
    zos.write(fileBytes);
    zos.flush();
    zos.closeEntry();
    zos.close();
    zos.finish();

  } catch(IOException ioe) {
    ioe.printStackTrace();
    LOG.error("Error writing compressed file", ioe);
  }

  // Extract zipped file as byte array
  byte[] byteCompressedFile = baos.toByteArray();

  LOG.info("Zipped successfully");

  return byteCompressedFile;

}

The section on encryption is optional.