AES256 decrypt : org.tukaani.xz.CorruptedInputException: Compressed data is corrupt exception

[Rajarshi]

I'm a beginner to compression. I am trying to unpack a password protected AES 256 encoded 7z file but getting below error. It is working find without password protected 7z file.

Am I missing anything?

Error
org.tukaani.xz.CorruptedInputException: Compressed data is corrupt
at org.tukaani.xz.rangecoder.RangeDecoderFromStream.<init>(Unknown Source)
at org.tukaani.xz.LZMAInputStream.initialize(Unknown Source)
at org.tukaani.xz.LZMAInputStream.initialize(Unknown Source)
at org.tukaani.xz.LZMAInputStream.<init>(Unknown Source)
at org.apache.commons.compress.archivers.sevenz.LZMADecoder.decode(LZMADecoder.java:43)
at org.apache.commons.compress.archivers.sevenz.Coders.addDecoder(Coders.java:76)
at org.apache.commons.compress.archivers.sevenz.SevenZFile.buildDecoderStack(SevenZFile.java:933)
at org.apache.commons.compress.archivers.sevenz.SevenZFile.buildDecodingStream(SevenZFile.java:909)
at org.apache.commons.compress.archivers.sevenz.SevenZFile.getNextEntry(SevenZFile.java:222)
at com.concept.utilities.zip.DecryptionUtil.SevenZFile(DecryptionUtil.java:50)
at com.concept.utilities.zip.DecryptionUtil.main(DecryptionUtil.java:107)

There is the code I have written
public void SevenZFile(String directory, String encryptCompressFileName, String password) {

    SevenZFile sevenZFile = null;
    SevenZArchiveEntry entry = null;

    try {

        File file = new File(directory+encryptCompressFileName);
        byte[] inputData = new byte[(int) file.length()];
        FileInputStream fis = new FileInputStream(file);
        fis.read(inputData);
        fis.close();

        // SeekableInMemoryByteChannel inMemoryByteChannel = new SeekableInMemoryByteChannel(inputData);
        if(null != password){
            byte[] pass = password.getBytes("UTF16");
            sevenZFile = new SevenZFile(file, pass);
        }else{
            sevenZFile = new SevenZFile(file);
        }

        // Go through all entries
        while (null != (entry = sevenZFile.getNextEntry())) {

            // Maybe filter by name. Name can contain a path.
            String processingFileName = entry.getName();
            if (entry.isDirectory()) {
                System.out.println(String.format("Found directory entry %s", processingFileName));

            } else {

                // If this is a file, we read the file content into a ByteArrayOutputStream ...
                System.out.println(String.format("Unpacking start %s ...", processingFileName));
                ByteArrayOutputStream contentBytes = new ByteArrayOutputStream();

                // ... using a small buffer byte array.
                byte[] buffer = new byte[2048];
                int bytesRead;

                while ((bytesRead = sevenZFile.read(buffer)) != -1) {
                    contentBytes.write(buffer, 0, bytesRead);
                }

                if (processingFileName.endsWith("xls")) {
                    // Writing into xls
                    Workbook wb = new HSSFWorkbook();
                    //String safeName = WorkbookUtil.createSafeSheetName(processingFileName);
                    //Sheet sheet = wb.createSheet(safeName);
                    FileOutputStream fileOut = new FileOutputStream(directory+processingFileName);
                    fileOut.write(contentBytes.toByteArray());
                    fileOut.flush();
                    wb.write(fileOut);
                    fileOut.close();
                    wb.close();
                }else{ //regular file
                    System.out.println(contentBytes.toString("UTF-8"));
                }
                System.out.println(String.format("Unpacking finish %s ...", processingFileName));   
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            sevenZFile.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

[Lasse Collin]

You are using Apache Commons Compress which uses XZ for Java which is the thing I maintain. I'm not very familiar with Commons Compress APIs.

Looking at your code, password.getBytes("UTF16") looks suspicious. Instead of "UTF16" or "UTF-16" (which uses byte-order mark for autodetection and defaults to big endian), you probably want "UTF-16LE". The .7z format is little endian and encodes strings in UTF-16LE.

See:
https://docs.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html
https://commons.apache.org/proper/commons-compress/apidocs/org/apache/commons/compress/archivers/sevenz/SevenZFile.html#SevenZFile-java.nio.channels.SeekableByteChannel-byte:A-