CODEWITHSUNDEEP
javacompressionqr-code
Rakesh Kumar
Rakesh Kumar

Reputation: 157

Decompressing byte array in java

While decompressing adhaar qr code sample data steps follow as given https://uidai.gov.in/images/resource/User_manulal_QR_Code_15032019.pdf, I got java.util.zip.DataFormatException: incorrect header check error while decompressing the byte array

// getting aadhaar sample qr code data from

// https://uidai.gov.in/images/resource/User_manulal_QR_Code_15032019.pdf

String s ="taking  here Aadhaar sample qr code data";
BigInteger bi = new BigInteger(s, 10); 

byte[] array = bi.toByteArray();    
Inflater decompresser = new Inflater(true);
decompresser.setInput(array);
ByteArrayOutputStream outputStream = new 
ByteArrayOutputStream(array.length);
byte[] buffer = new byte[1024];  
while (!decompresser.finished()) {  
    int count = decompresser.inflate(buffer);  
    outputStream.write(buffer, 0, count);  
}  
outputStream.close();  
byte[] output = outputStream.toByteArray(); 
String st = new String(output, 0, 255, "ISO-8859-1");
System.out.println("==========="+st);

Upvotes: 3

Views: 4550

Answers (2)

Atul Salgaonkar
Atul Salgaonkar

Reputation: 256

This is the project which decoded the data Correctly: https://github.com/dimagi/AadharUID

It supports secure, xml and uid_number type

Upvotes: 2

ABHISHEK KUMAR
ABHISHEK KUMAR

Reputation: 154

The problem is that you are using Inflater class of java which uses Zlib compression algorithm. However in UIDAI secure QR code, GZip compression algorithm is being used. So the decompression logic has to be modified as following:-

ByteArrayOutputStream os = new ByteArrayOutputStream();
        try {
            ByteArrayInputStream in = new ByteArrayInputStream(data);
            GZIPInputStream gis = new GZIPInputStream(in);
            byte[] buffer = new byte[1024];
            int len;
            while((len = gis.read(buffer)) != -1){                                        os.write(buffer, 0, len);
            }
            os.close();
            gis.close();
        }
        catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        byte[] output = os.toByteArray();

Upvotes: 5

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