GZipOutputStream problem!

Question

Hello,
I am running into a weird problem which is intermittent.
I am trying to generate an encrypted URL from an input string.
I am using URLEncoding, MD5Checksum, zipping (for compression) and using BlowFish for encryption. The input string is a variable length string though in this case, the problem is showing up in a string of fixed length.
The compression method uses GZipOutputStream with ByteArrayOutPutStream as the underlying stream to compress data.
This compressed data is then used as the input to BlowFish for getting the encrypted result which is then Base64 and URL encoded.
The problem is that if the encryption program is called in a loop with the same payload string as input, the encryption program sometimes generates an invalid URL. Following is the zip utility.
private static byte[] zipIt ( String parameterString )
        byte[] zipped;
        try {
            ByteArrayOutputStream catcher = new ByteArrayOutputStream();
            GZIPOutputStream gzipOut = new GZIPOutputStream( catcher );
            byte[] bytesToZip = parameterString.getBytes();
            gzipOut.write( bytesToZip, 0, bytesToZip.length );
            gzipOut.close();
            return catcher.toByteArray();
        catch ( Exception ioe ) {
            ioe.printStackTrace();
            return "error".getBytes();
    }The length of the compressed string generated by this method is different (for the most part it is the same) on certain iterations.
Is there an issue with the GZipOutputStream or the ByteArrayOutputStream? By the way, I tried this using both JDK 1.3.3 and 1.5.03.
Thanks in advance,
coderiyer

Answer 1

Thanks for the response. For Base64, an open source class is being used. This http://iharder.sourceforge.net/current/java/base64/ is the link to this class. Version 1.3.6 is being used. What I don't understand is even if I don't remove the URLDecode on the decryption side after removing URLencode on the encryption end, it still works. Following is the legacy code for encryption/decryption. By the way, to answer your earlier question, the client is having problems in using the encrypted URL when it gets decrypted but it has been found that the encryption was incorrect in the first place.
Thanks for your help again.
coderiyer
public static String encryptPayload (String payload, String authKey) {
try {
// Steps for creating an encrypted URL:
// 1 - Calculate the checksum
// 2 - Concatenate the checksum and payload
// 3 - URL Encode
// 4 - Compress the string using zipIt (GZIP)
// 5 - Encrypt using Blowfish and SunJCE
// 6 - Base 64 encode
// 7 - URL encode
// 8 - Return the complete string
BlowFishUtil bfUtil = new BlowFishUtil();
logger.debug("---------------------------------------");
logger.debug("encryptPayload payload");
logger.debug(payload);
logger.debug("authKey");
logger.debug(authKey);
logger.debug("---------------------------------------");
String sCheckSum = getMD5Checksum(payload);
String encodeBuffer = sCheckSum + payload;
logger.debug("---------------------------------------");
logger.debug("sCheckSum");
logger.debug(sCheckSum);
logger.debug("---------------------------------------");
encodeBuffer = URLEncoder.encode(encodeBuffer);
logger.debug("---------------------------------------");
logger.debug("URLEncoder.encode");
logger.debug(encodeBuffer);
logger.debug("---------------------------------------");
byte[] aryEncodeBuf = zipIt(encodeBuffer);
logger.debug("---------------------------------------");
logger.debug("zipIt");
logger.debug(new String(aryEncodeBuf));
logger.debug("---------------------------------------");
aryEncodeBuf = bfUtil.encryptSecretKey(authKey.getBytes(),aryEncodeBuf);
logger.debug("---------------------------------------");
logger.debug("encryptSecretKey");
logger.debug(new String(aryEncodeBuf));
logger.debug("---------------------------------------");
encodeBuffer = Base64.encodeBytes(aryEncodeBuf);
logger.debug("---------------------------------------");
logger.debug("Base64.encodeBytes");
logger.debug(encodeBuffer);
logger.debug("---------------------------------------");
encodeBuffer = URLEncoder.encode(encodeBuffer);
logger.debug("---------------------------------------");
logger.debug("URLEncoder.encode");
logger.debug(encodeBuffer);
logger.debug("---------------------------------------");
return encodeBuffer;
catch (Exception e) {
logger.debug("[PDFWebApiDelegate:encryptPayload] - Exception : " + e );
return null;
public static String decryptPayload (String payload, String authKey) {
try {
// Steps for decrypted a URL:
// 1 - URL decode
// 2 - Base 64 encode
// 3 - Decrypt using Blowfish and SunJCE
// 4 - Decompress the string using unzipIt (GZIP)
// 5 - Strip off the checksum, calculate the checksum from the payload
// and verify they match
// 6 - Return the decrypted payload
String decodeBuffer = "";
BlowFishUtil bfUtil = new BlowFishUtil();
logger.debug("---------------------------------------");
logger.debug("decryptPayload payload");
logger.debug(payload);
logger.debug("authKey");
logger.debug(authKey);
logger.debug("---------------------------------------");
decodeBuffer = URLDecoder.decode(payload);
logger.debug("---------------------------------------");
logger.debug("URLDecoder.decode");
logger.debug(decodeBuffer);
logger.debug("---------------------------------------");
decodeBuffer = Base64.decodeToString(decodeBuffer);
logger.debug("---------------------------------------");
logger.debug("Base64.decodeToString");
logger.debug(decodeBuffer);
logger.debug("---------------------------------------");
byte[] aryDecodeBuf = bfUtil.decryptSecretKey(authKey.getBytes(), decodeBuffer.getBytes());
logger.debug("---------------------------------------");
logger.debug("decryptSecretKey");
logger.debug(new String(aryDecodeBuf));
logger.debug("---------------------------------------");
aryDecodeBuf = unzipIt(aryDecodeBuf);
logger.debug("---------------------------------------");
logger.debug("unzipIt");
logger.debug(new String(aryDecodeBuf));
logger.debug("---------------------------------------");
String sBuf = new String(aryDecodeBuf);
logger.debug("---------------------------------------");
logger.debug("new String(aryDecodeBuf)");
logger.debug(sBuf);
logger.debug("---------------------------------------");
sBuf = URLDecoder.decode(sBuf);
logger.debug("---------------------------------------");
logger.debug("URLDecoder.decode");
logger.debug(sBuf);
logger.debug("---------------------------------------");
int iPos = sBuf.indexOf("st=");
logger.debug("---------------------------------------");
logger.debug("iPos of st=");
logger.debug(String.valueOf(iPos));
logger.debug("---------------------------------------");
if (iPos>=0) {
String sURLCheckSum = sBuf.substring(0,iPos);
sBuf = sBuf.substring(iPos,sBuf.length());
String sCheckSum = getMD5Checksum(sBuf);
if (!sCheckSum.equals(sURLCheckSum)) {
logger.debug("[PDFWebApiDelegate:decryptPayload] ERROR: Checksums do not match.");
logger.debug("---------------------------------------");
logger.debug("urlchecksum");
logger.debug(sURLCheckSum);
logger.debug("calcedchecksum");
logger.debug(sCheckSum);
logger.debug("sBuf");
logger.debug(sBuf);
logger.debug("---------------------------------------");
return new String(sBuf);
catch (Exception e) {
logger.debug("[PDFWebApiDelegate:decryptPayload] - Exception : " + e );
return null;
* Creates an MD5 checksum for the passed <code>String</code>
* @param mess The message for which we are determining the check sum.
* @return String The checksum string
private static String getMD5Checksum( String mess ){
String hexHashCode = "";
String hashCode = "";
try {
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] message = mess.getBytes("UTF-8");
md.update( message );
byte[] hash = md.digest();
for ( int i=0; i < hash.length; i++ ){
int x = hash[i] & 0xFF;
if (x < 0x10) {
hexHashCode += "0";
hexHashCode += (Integer.toHexString(x));
hashCode += hash[i]+" _ ";
catch (Exception e) {
e.printStackTrace();
return "error";
return hexHashCode;
private static byte[] zipIt ( String parameterString )
byte[] zipped;
try {
ByteArrayOutputStream catcher = new ByteArrayOutputStream();
GZIPOutputStream gzipOut = new GZIPOutputStream( catcher );
byte[] bytesToZip = parameterString.getBytes();
gzipOut.write( bytesToZip, 0, bytesToZip.length );
gzipOut.close();
return catcher.toByteArray();
catch ( Exception ioe ) {
ioe.printStackTrace();
return "error".getBytes();
private static byte[] unzipIt ( byte[] buffer ) {
ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
ByteArrayInputStream inBuffer = new ByteArrayInputStream(buffer);
try {
GZIPInputStream gzip = new GZIPInputStream(inBuffer);
byte[] tmpBuffer = new byte[256];
int n;
while ((n = gzip.read(tmpBuffer)) >= 0) {
outBuffer.write(tmpBuffer, 0, n);
return outBuffer.toByteArray();
catch (Exception e) {
logger.debug("[PDFWebApiDelegate:unzipIt] - Exception : "+e);
return null;
}