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convert binary data to gzip file and decompress to a string c#

I am trying to decode binary data that represents a gzip file, I need to decompress the gzip so I can get the nbt (minecraft notation thing) string that is in the gzip, but I keep getting the following error at GZipStream.Read:
The archive entry was compressed using an unsupported compression method.
Does anyone have any idea on how to do this?
This is my code:
public static string Decompress(string input)
{
byte[] compressed = Convert.FromBase64String(input); //This is the binary data
byte[] decompressed = Decompress(compressed);
return Encoding.UTF8.GetString(decompressed);
}
private static byte[] Decompress(byte[] input)
{
using (var source = new MemoryStream(input))
{
byte[] lengthBytes = new byte[4];
source.Read(lengthBytes, 0, 4);
var length = BitConverter.ToInt32(lengthBytes, 0);
using (var decompressionStream = new GZipStream(source,
CompressionMode.Decompress))
{
var result = new byte[length];
decompressionStream.Read(result, 0, length); //Error
return result;
}
}
}

This should do it for you:
public static string Decompress(string value)
{
byte[] buffer = Convert.FromBase64String(value);
byte[] decompressed;
using (var inputStream = new MemoryStream(buffer))
{
using var outputStream = new MemoryStream();
using (var gzip = new GZipStream(inputStream, CompressionMode.Decompress, leaveOpen: true))
{
gzip.CopyTo(outputStream);
}
decompressed = outputStream.ToArray();
}
return Encoding.UTF8.GetString(decompressed);
}

Base64 to ZIP Base64 without writing to disk [duplicate]

I am newbie in .net. I am doing compression and decompression string in C#. There is a XML and I am converting in string and after that I am doing compression and decompression.There is no compilation error in my code except when I decompression my code and return my string, its returning only half of the XML.
Below is my code, please correct me where I am wrong.
Code:
class Program
{
public static string Zip(string value)
{
//Transform string into byte[]
byte[] byteArray = new byte[value.Length];
int indexBA = 0;
foreach (char item in value.ToCharArray())
{
byteArray[indexBA++] = (byte)item;
}
//Prepare for compress
System.IO.MemoryStream ms = new System.IO.MemoryStream();
System.IO.Compression.GZipStream sw = new System.IO.Compression.GZipStream(ms, System.IO.Compression.CompressionMode.Compress);
//Compress
sw.Write(byteArray, 0, byteArray.Length);
//Close, DO NOT FLUSH cause bytes will go missing...
sw.Close();
//Transform byte[] zip data to string
byteArray = ms.ToArray();
System.Text.StringBuilder sB = new System.Text.StringBuilder(byteArray.Length);
foreach (byte item in byteArray)
{
sB.Append((char)item);
}
ms.Close();
sw.Dispose();
ms.Dispose();
return sB.ToString();
}
public static string UnZip(string value)
{
//Transform string into byte[]
byte[] byteArray = new byte[value.Length];
int indexBA = 0;
foreach (char item in value.ToCharArray())
{
byteArray[indexBA++] = (byte)item;
}
//Prepare for decompress
System.IO.MemoryStream ms = new System.IO.MemoryStream(byteArray);
System.IO.Compression.GZipStream sr = new System.IO.Compression.GZipStream(ms,
System.IO.Compression.CompressionMode.Decompress);
//Reset variable to collect uncompressed result
byteArray = new byte[byteArray.Length];
//Decompress
int rByte = sr.Read(byteArray, 0, byteArray.Length);
//Transform byte[] unzip data to string
System.Text.StringBuilder sB = new System.Text.StringBuilder(rByte);
//Read the number of bytes GZipStream red and do not a for each bytes in
//resultByteArray;
for (int i = 0; i < rByte; i++)
{
sB.Append((char)byteArray[i]);
}
sr.Close();
ms.Close();
sr.Dispose();
ms.Dispose();
return sB.ToString();
}
static void Main(string[] args)
{
XDocument doc = XDocument.Load(#"D:\RSP.xml");
string val = doc.ToString(SaveOptions.DisableFormatting);
val = Zip(val);
val = UnZip(val);
}
}
My XML size is 63KB.

The code to compress/decompress a string
public static void CopyTo(Stream src, Stream dest) {
byte[] bytes = new byte[4096];
int cnt;
while ((cnt = src.Read(bytes, 0, bytes.Length)) != 0) {
dest.Write(bytes, 0, cnt);
}
}
public static byte[] Zip(string str) {
var bytes = Encoding.UTF8.GetBytes(str);
using (var msi = new MemoryStream(bytes))
using (var mso = new MemoryStream()) {
using (var gs = new GZipStream(mso, CompressionMode.Compress)) {
//msi.CopyTo(gs);
CopyTo(msi, gs);
}
return mso.ToArray();
}
}
public static string Unzip(byte[] bytes) {
using (var msi = new MemoryStream(bytes))
using (var mso = new MemoryStream()) {
using (var gs = new GZipStream(msi, CompressionMode.Decompress)) {
//gs.CopyTo(mso);
CopyTo(gs, mso);
}
return Encoding.UTF8.GetString(mso.ToArray());
}
}
static void Main(string[] args) {
byte[] r1 = Zip("StringStringStringStringStringStringStringStringStringStringStringStringStringString");
string r2 = Unzip(r1);
}
Remember that Zip returns a byte[], while Unzip returns a string. If you want a string from Zip you can Base64 encode it (for example by using Convert.ToBase64String(r1)) (the result of Zip is VERY binary! It isn't something you can print to the screen or write directly in an XML)
The version suggested is for .NET 2.0, for .NET 4.0 use the MemoryStream.CopyTo.
IMPORTANT: The compressed contents cannot be written to the output stream until the GZipStream knows that it has all of the input (i.e., to effectively compress it needs all of the data). You need to make sure that you Dispose() of the GZipStream before inspecting the output stream (e.g., mso.ToArray()). This is done with the using() { } block above. Note that the GZipStream is the innermost block and the contents are accessed outside of it. The same goes for decompressing: Dispose() of the GZipStream before attempting to access the data.

according to
this snippet
i use this code and it's working fine:
using System;
using System.IO;
using System.IO.Compression;
using System.Text;
namespace CompressString
{
internal static class StringCompressor
{
/// <summary>
/// Compresses the string.
/// </summary>
/// <param name="text">The text.</param>
/// <returns></returns>
public static string CompressString(string text)
{
byte[] buffer = Encoding.UTF8.GetBytes(text);
var memoryStream = new MemoryStream();
using (var gZipStream = new GZipStream(memoryStream, CompressionMode.Compress, true))
{
gZipStream.Write(buffer, 0, buffer.Length);
}
memoryStream.Position = 0;
var compressedData = new byte[memoryStream.Length];
memoryStream.Read(compressedData, 0, compressedData.Length);
var gZipBuffer = new byte[compressedData.Length + 4];
Buffer.BlockCopy(compressedData, 0, gZipBuffer, 4, compressedData.Length);
Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gZipBuffer, 0, 4);
return Convert.ToBase64String(gZipBuffer);
}
/// <summary>
/// Decompresses the string.
/// </summary>
/// <param name="compressedText">The compressed text.</param>
/// <returns></returns>
public static string DecompressString(string compressedText)
{
byte[] gZipBuffer = Convert.FromBase64String(compressedText);
using (var memoryStream = new MemoryStream())
{
int dataLength = BitConverter.ToInt32(gZipBuffer, 0);
memoryStream.Write(gZipBuffer, 4, gZipBuffer.Length - 4);
var buffer = new byte[dataLength];
memoryStream.Position = 0;
using (var gZipStream = new GZipStream(memoryStream, CompressionMode.Decompress))
{
gZipStream.Read(buffer, 0, buffer.Length);
}
return Encoding.UTF8.GetString(buffer);
}
}
}
}

With the advent of .NET 4.0 (and higher) with the Stream.CopyTo() methods, I thought I would post an updated approach.
I also think the below version is useful as a clear example of a self-contained class for compressing regular strings to Base64 encoded strings, and vice versa:
public static class StringCompression
{
/// <summary>
/// Compresses a string and returns a deflate compressed, Base64 encoded string.
/// </summary>
/// <param name="uncompressedString">String to compress</param>
public static string Compress(string uncompressedString)
{
byte[] compressedBytes;
using (var uncompressedStream = new MemoryStream(Encoding.UTF8.GetBytes(uncompressedString)))
{
using (var compressedStream = new MemoryStream())
{
// setting the leaveOpen parameter to true to ensure that compressedStream will not be closed when compressorStream is disposed
// this allows compressorStream to close and flush its buffers to compressedStream and guarantees that compressedStream.ToArray() can be called afterward
// although MSDN documentation states that ToArray() can be called on a closed MemoryStream, I don't want to rely on that very odd behavior should it ever change
using (var compressorStream = new DeflateStream(compressedStream, CompressionLevel.Fastest, true))
{
uncompressedStream.CopyTo(compressorStream);
}
// call compressedStream.ToArray() after the enclosing DeflateStream has closed and flushed its buffer to compressedStream
compressedBytes = compressedStream.ToArray();
}
}
return Convert.ToBase64String(compressedBytes);
}
/// <summary>
/// Decompresses a deflate compressed, Base64 encoded string and returns an uncompressed string.
/// </summary>
/// <param name="compressedString">String to decompress.</param>
public static string Decompress(string compressedString)
{
byte[] decompressedBytes;
var compressedStream = new MemoryStream(Convert.FromBase64String(compressedString));
using (var decompressorStream = new DeflateStream(compressedStream, CompressionMode.Decompress))
{
using (var decompressedStream = new MemoryStream())
{
decompressorStream.CopyTo(decompressedStream);
decompressedBytes = decompressedStream.ToArray();
}
}
return Encoding.UTF8.GetString(decompressedBytes);
}
}
Here’s another approach using the extension methods technique to extend the String class to add string compression and decompression. You can drop the class below into an existing project and then use thusly:
var uncompressedString = "Hello World!";
var compressedString = uncompressedString.Compress();
and
var decompressedString = compressedString.Decompress();
To wit:
public static class Extensions
{
/// <summary>
/// Compresses a string and returns a deflate compressed, Base64 encoded string.
/// </summary>
/// <param name="uncompressedString">String to compress</param>
public static string Compress(this string uncompressedString)
{
byte[] compressedBytes;
using (var uncompressedStream = new MemoryStream(Encoding.UTF8.GetBytes(uncompressedString)))
{
using (var compressedStream = new MemoryStream())
{
// setting the leaveOpen parameter to true to ensure that compressedStream will not be closed when compressorStream is disposed
// this allows compressorStream to close and flush its buffers to compressedStream and guarantees that compressedStream.ToArray() can be called afterward
// although MSDN documentation states that ToArray() can be called on a closed MemoryStream, I don't want to rely on that very odd behavior should it ever change
using (var compressorStream = new DeflateStream(compressedStream, CompressionLevel.Fastest, true))
{
uncompressedStream.CopyTo(compressorStream);
}
// call compressedStream.ToArray() after the enclosing DeflateStream has closed and flushed its buffer to compressedStream
compressedBytes = compressedStream.ToArray();
}
}
return Convert.ToBase64String(compressedBytes);
}
/// <summary>
/// Decompresses a deflate compressed, Base64 encoded string and returns an uncompressed string.
/// </summary>
/// <param name="compressedString">String to decompress.</param>
public static string Decompress(this string compressedString)
{
byte[] decompressedBytes;
var compressedStream = new MemoryStream(Convert.FromBase64String(compressedString));
using (var decompressorStream = new DeflateStream(compressedStream, CompressionMode.Decompress))
{
using (var decompressedStream = new MemoryStream())
{
decompressorStream.CopyTo(decompressedStream);
decompressedBytes = decompressedStream.ToArray();
}
}
return Encoding.UTF8.GetString(decompressedBytes);
}
}

I like #fubo's answer the best but I think this is much more elegant.
This method is more compatible because it doesn't manually store the length up front.
Also I've exposed extensions to support compression for string to string, byte[] to byte[], and Stream to Stream.
public static class ZipExtensions
{
public static string CompressToBase64(this string data)
{
return Convert.ToBase64String(Encoding.UTF8.GetBytes(data).Compress());
}
public static string DecompressFromBase64(this string data)
{
return Encoding.UTF8.GetString(Convert.FromBase64String(data).Decompress());
}
public static byte[] Compress(this byte[] data)
{
using (var sourceStream = new MemoryStream(data))
using (var destinationStream = new MemoryStream())
{
sourceStream.CompressTo(destinationStream);
return destinationStream.ToArray();
}
}
public static byte[] Decompress(this byte[] data)
{
using (var sourceStream = new MemoryStream(data))
using (var destinationStream = new MemoryStream())
{
sourceStream.DecompressTo(destinationStream);
return destinationStream.ToArray();
}
}
public static void CompressTo(this Stream stream, Stream outputStream)
{
using (var gZipStream = new GZipStream(outputStream, CompressionMode.Compress))
{
stream.CopyTo(gZipStream);
gZipStream.Flush();
}
}
public static void DecompressTo(this Stream stream, Stream outputStream)
{
using (var gZipStream = new GZipStream(stream, CompressionMode.Decompress))
{
gZipStream.CopyTo(outputStream);
}
}
}

This is an updated version for .NET 4.5 and newer using async/await and IEnumerables:
public static class CompressionExtensions
{
public static async Task<IEnumerable<byte>> Zip(this object obj)
{
byte[] bytes = obj.Serialize();
using (MemoryStream msi = new MemoryStream(bytes))
using (MemoryStream mso = new MemoryStream())
{
using (var gs = new GZipStream(mso, CompressionMode.Compress))
await msi.CopyToAsync(gs);
return mso.ToArray().AsEnumerable();
}
}
public static async Task<object> Unzip(this byte[] bytes)
{
using (MemoryStream msi = new MemoryStream(bytes))
using (MemoryStream mso = new MemoryStream())
{
using (var gs = new GZipStream(msi, CompressionMode.Decompress))
{
// Sync example:
//gs.CopyTo(mso);
// Async way (take care of using async keyword on the method definition)
await gs.CopyToAsync(mso);
}
return mso.ToArray().Deserialize();
}
}
}
public static class SerializerExtensions
{
public static byte[] Serialize<T>(this T objectToWrite)
{
using (MemoryStream stream = new MemoryStream())
{
BinaryFormatter binaryFormatter = new BinaryFormatter();
binaryFormatter.Serialize(stream, objectToWrite);
return stream.GetBuffer();
}
}
public static async Task<T> _Deserialize<T>(this byte[] arr)
{
using (MemoryStream stream = new MemoryStream())
{
BinaryFormatter binaryFormatter = new BinaryFormatter();
await stream.WriteAsync(arr, 0, arr.Length);
stream.Position = 0;
return (T)binaryFormatter.Deserialize(stream);
}
}
public static async Task<object> Deserialize(this byte[] arr)
{
object obj = await arr._Deserialize<object>();
return obj;
}
}
With this you can serialize everything BinaryFormatter supports, instead only of strings.
Edit:
In case, you need take care of Encoding, you could just use Convert.ToBase64String(byte[])...
Take a look at this answer if you need an example!

For those who still getting The magic number in GZip header is not correct. Make sure you are passing in a GZip stream. ERROR
and if your string was zipped using php you'll need to do something like:
public static string decodeDecompress(string originalReceivedSrc) {
byte[] bytes = Convert.FromBase64String(originalReceivedSrc);
using (var mem = new MemoryStream()) {
//the trick is here
mem.Write(new byte[] { 0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00 }, 0, 8);
mem.Write(bytes, 0, bytes.Length);
mem.Position = 0;
using (var gzip = new GZipStream(mem, CompressionMode.Decompress))
using (var reader = new StreamReader(gzip)) {
return reader.ReadToEnd();
}
}
}

We can reduce code complexity by using StreamReader and StreamWriter rather than manually converting strings to byte arrays. Three streams is all you need:
public static byte[] Zip(string uncompressed)
{
byte[] ret;
using (var outputMemory = new MemoryStream())
{
using (var gz = new GZipStream(outputMemory, CompressionLevel.Optimal))
{
using (var sw = new StreamWriter(gz, Encoding.UTF8))
{
sw.Write(uncompressed);
}
}
ret = outputMemory.ToArray();
}
return ret;
}
public static string Unzip(byte[] compressed)
{
string ret = null;
using (var inputMemory = new MemoryStream(compressed))
{
using (var gz = new GZipStream(inputMemory, CompressionMode.Decompress))
{
using (var sr = new StreamReader(gz, Encoding.UTF8))
{
ret = sr.ReadToEnd();
}
}
}
return ret;
}

For .net6 cross platform Compression/Decompression string with C# using SharpZipLib library. Test for ubuntu(18.0.x) and windows.
#region helper
private byte[] Zip(string text)
{
if (text == null)
return null;
byte[] ret;
using (var outputMemory = new MemoryStream())
{
using (var gz = new GZipStream(outputMemory, CompressionLevel.Optimal))
{
using (var sw = new StreamWriter(gz, Encoding.UTF8))
{
sw.Write(text);
}
}
ret = outputMemory.ToArray();
}
return ret;
}
private string Unzip(byte[] bytes)
{
string ret = null;
using (var inputMemory = new MemoryStream(bytes))
{
using (var gz = new GZipStream(inputMemory, CompressionMode.Decompress))
{
using (var sr = new StreamReader(gz, Encoding.UTF8))
{
ret = sr.ReadToEnd();
}
}
}
return ret;
}
#endregion

Method that return a string with an specifc extension

Im a long time trying to solve one problem. I have one method that Serialize a string, follows the code:
XmlRetorno()
var algumasDef = new XmlWriterSettings {
Indent = true,
OmitXmlDeclaration = true
};
var nameSpace = new XmlSerializerNamespaces();
nameSpace.Add(string.Empty, "urn:sngpc-schema");
var meuXml = new XmlSerializer(GetType(), "urn:sngpc-schema");
using (var minhaString = new StringWriterWithEncoding(Encoding.GetEncoding("iso-8859-1"))) {
using (var escreve = XmlWriter.Create(minhaString, algumasDef)) {
meuXml.Serialize(escreve, this, nameSpace);
}
return minhaString.ToString();
}
Then, my next step is to compact that string to a zip file, my method to zip.
CompactXml()
string ziparEssaString = msg.XmlRetorno();
byte[] byteArray = new byte[ziparEssaString.Length];
int indexBA = 0;
foreach (char item in ziparEssaString.ToArray()) {
byteArray[indexBA++] = (byte)item;
}
//prepare to compress
using (MemoryStream ms = new MemoryStream()) {
using (GZipStream sw = new GZipStream(ms, CompressionMode.Compress)) {
sw.Write(byteArray, 0, byteArray.Length);
}
//transform bytes[] zip to string
byteArray = ms.ToArray();
StringBuilder sB = new StringBuilder(byteArray.Length);
foreach (byte item in byteArray) {
sB.Append((char)item);
}
return sB.ToString();
}
I need to compress a string that is formatted .xml and when I unpack I need the extension to be .xml too, my webservice return an error. Please, i need one light.

Decompress string in java from compressed string in C#

I was searching for the correct solution to decompress the string in java coming from c# code.I tried myself with lot of techniques in java like(gzip,inflatter etc.).but didn't get the solution.i got some error while trying to decompress the string in java from compressed string from c# code.
My C# code to compress the string is,
public static string CompressString(string text)
{
byte[] byteArray = Encoding.GetEncoding(1252).GetBytes(text);// Encoding.ASCII.GetBytes(text);
using (var ms = new MemoryStream())
{
// Compress the text
using (var ds = new DeflateStream(ms, CompressionMode.Compress))
{
ds.Write(byteArray, 0, byteArray.Length);
}
return Convert.ToBase64String(ms.ToArray());
}
}
And decompress the string in java using,
private static void compressAndDecompress(){
try {
// Encode a String into bytes
String string = "xxxxxxSAMPLECOMPRESSEDSTRINGxxxxxxxxxx";
// // Compress the bytes
byte[] decoded = Base64.decodeBase64(string.getBytes());
byte[] output = new byte[4096];
// Decompress the bytes
Inflater decompresser = new Inflater();
decompresser.setInput(decoded);
int resultLength = decompresser.inflate(output);
decompresser.end();
// Decode the bytes into a String
String outputString = new String(output, 0, resultLength, "UTF-8");
System.out.println(outputString);
} catch(java.io.UnsupportedEncodingException ex) {
ex.printStackTrace();
} catch (java.util.zip.DataFormatException ex) {
ex.printStackTrace();
}
}
I get this exception when running the above code:
java.util.zip.DataFormatException: incorrect header check
Kindly give me the sample code in java to decompress the string java.Thanks

My C# code to compress is
private string Compress(string text)
{
byte[] buffer = Encoding.UTF8.GetBytes(text);
MemoryStream ms = new MemoryStream();
using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress, true))
{
zip.Write(buffer, 0, buffer.Length);
}
ms.Position = 0;
MemoryStream outStream = new MemoryStream();
byte[] compressed = new byte[ms.Length];
ms.Read(compressed, 0, compressed.Length);
byte[] gzBuffer = new byte[compressed.Length + 4];
System.Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length);
System.Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4);
return Convert.ToBase64String(gzBuffer);
}
Java code to decompress the text is
private String Decompress(String compressedText)
{
byte[] compressed = compressedText.getBytes("UTF8");
compressed = org.apache.commons.codec.binary.Base64.decodeBase64(compressed);
byte[] buffer=new byte[compressed.length-4];
buffer = copyForDecompression(compressed,buffer, 4, 0);
final int BUFFER_SIZE = 32;
ByteArrayInputStream is = new ByteArrayInputStream(buffer);
GZIPInputStream gis = new GZIPInputStream(is, BUFFER_SIZE);
StringBuilder string = new StringBuilder();
byte[] data = new byte[BUFFER_SIZE];
int bytesRead;
while ((bytesRead = gis.read(data)) != -1)
{
string.append(new String(data, 0, bytesRead));
}
gis.close();
is.close();
return string.toString();
}
private byte[] copyForDecompression(byte[] b1,byte[] b2,int srcoffset,int dstoffset)
{
for(int i=0;i<b2.length && i<b1.length;i++)
{
b2[i]=b1[i+4];
}
return b2;
}
This code works perfectly fine for me.

Had exactly the same issue. Could solve it via
byte[] compressed = Base64Utils.decodeFromString("mybase64encodedandwithc#zippedcrap");
Inflater decompresser = new Inflater(true);
decompresser.setInput(compressed);
byte[] result = new byte[4096];
decompresser.inflate(result);
decompresser.end();
System.out.printf(new String(result));
The magic happens with the boolen parameter on instantiating the Inflator
BW Hubert

For beloved googlers,
As #dbw mentioned,
according to post How to decompress stream deflated with java.util.zip.Deflater in .NET?,
java.util.zip.deflater equivalent in c# the default deflater used in C#
is not having any java equivalent that's why users prefer Gzip, Ziplib
or some other zip techniques.
a relatively simple method would be using GZip.
And for the accepted answer, one problem is that in this method you should append the data size to the compressed string yourself, and more importantly as per my own experience in our production app, It is buggy when the string reaches ~2000 chars!
the bug is in the System.io.Compression.GZipStream
any way using SharpZipLib in c# the problem goes away and everything would be as simple as following snippets:
JAVA:
import android.util.Base64;
import com.google.android.gms.common.util.IOUtils;
import org.jetbrains.annotations.Nullable;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
public class CompressionHelper {
#Nullable
public static String compress(#Nullable String data) {
if(data == null || data.length() == 0)
return null;
try {
// Create an output stream, and a gzip stream to wrap over.
ByteArrayOutputStream bos = new ByteArrayOutputStream(data.length());
GZIPOutputStream gzip = new GZIPOutputStream(bos);
// Compress the input string
gzip.write(data.getBytes());
gzip.close();
byte[] compressed;
// Convert to base64
compressed = Base64.encode(bos.toByteArray(),Base64.NO_WRAP);
bos.close();
// return the newly created string
return new String(compressed);
} catch(IOException e) {
return null;
}
}
#Nullable
public static String decompress(#Nullable String compressedText) {
if(compressedText == null || compressedText.length() == 0)
return null;
try {
// get the bytes for the compressed string
byte[] compressed = compressedText.getBytes("UTF-8");
// convert the bytes from base64 to normal string
compressed = Base64.decode(compressed, Base64.NO_WRAP);
ByteArrayInputStream bis = new ByteArrayInputStream(compressed);
GZIPInputStream gis = new GZIPInputStream(bis);
byte[] bytes = IOUtils.toByteArray(gis);
return new String(bytes, "UTF-8");
}catch (IOException e){
e.printStackTrace();
}
return null;
}
}
and c#:
using ICSharpCode.SharpZipLib.GZip; //PM> Install-Package SharpZipLib
using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace GeneralTools
{
public static class CompressionTools
{
public static string CompressString(string text)
{
if (string.IsNullOrEmpty(text))
return null;
byte[] buffer = Encoding.UTF8.GetBytes(text);
using (var compressedStream = new MemoryStream())
{
GZip.Compress(new MemoryStream(buffer), compressedStream, false);
byte[] compressedData = compressedStream.ToArray();
return Convert.ToBase64String(compressedData);
}
}
public static string DecompressString(string compressedText)
{
if (string.IsNullOrEmpty(compressedText))
return null;
byte[] gZipBuffer = Convert.FromBase64String(compressedText);
using (var memoryStream = new MemoryStream())
{
using (var compressedStream = new MemoryStream(gZipBuffer))
{
var decompressedStream = new MemoryStream();
GZip.Decompress(compressedStream, decompressedStream, false);
return Encoding.UTF8.GetString(decompressedStream.ToArray()).Trim();
}
}
}
}
}
you may also find the codes here

If anyone still interested, here's my full solution with outputstream to handle unknown string size. Using C# DeflateStream and Java Inflater (based on Hubert Ströbitzer answer).
C# Compression:
string CompressString(string raw)
{
byte[] uncompressedData = Encoding.UTF8.GetBytes(raw);
MemoryStream output = new MemoryStream();
using (DeflateStream dStream = new DeflateStream(output, CompressionLevel.Optimal))
{
dStream.Write(uncompressedData, 0, uncompressedData.Length);
}
string compressedString = Convert.ToBase64String(output.ToArray());
return compressedString;
}
Java decompress:
String decompressString(String compressedString) {
byte[] compressed = Base64Utils.decodeFromString(compressedString);
Inflater inflater = new Inflater(true);
inflater.setInput(compressed);
//Using output stream to handle unknown size of decompressed string
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
try {
while(!inflater.finished()){
int count = inflater.inflate(buffer);
outputStream.write(buffer, 0, count);
}
inflater.end();
outputStream.close();
} catch (DataFormatException e) {
//Handle DataFormatException
} catch (IOException e) {
//Handle IOException
}
return outputStream.toString();
}

BinaryFormatter & CryptoStream problem when deserializing

I'm getting a bit desperate here. I'm trying to write an encrypted file with a serialized object to disk and later retrieve the file, decrypt it and deserialize the object back.
UPDATE:
I refactored the code to this:
using (Stream innerStream = File.Create(this.GetFullFileNameForUser(securityContext.User, applicationName)))
{
using (Stream cryptoStream = new CryptoStream(innerStream, GetCryptoProvider().CreateEncryptor(), CryptoStreamMode.Write))
{
// 3. write to the cryptoStream
//BinaryFormatter bf = new BinaryFormatter();
//bf.Serialize(cryptoStream, securityContext);
XmlSerializer xs = new XmlSerializer(typeof(SecurityContextDTO));
xs.Serialize(cryptoStream, securityContext);
}
}
using (Stream innerStream = File.Open(this.GetFullFileNameForUser(user, applicationName), FileMode.Open))
{
using (Stream cryptoStream = new CryptoStream(innerStream, GetCryptoProvider().CreateDecryptor(), CryptoStreamMode.Read))
{
//BinaryFormatter bf = new BinaryFormatter();
//return (SecurityContextDTO)bf.Deserialize(cryptoStream);
XmlSerializer xs = new XmlSerializer(typeof(SecurityContextDTO));
//CryptographicException here
return (SecurityContextDTO)xs.Deserialize(cryptoStream);
}
}
Now I'm getting a cryptographic exception on deserialize: Bad Data
ORIGINAL:
I'm doing this:
public void StoreToFile(SecurityContextDTO securityContext, string applicationName)
{
if (securityContext.LoginResult.IsOfflineMode == false)
{
Stream stream = null;
CryptoStream crStream = null;
try
{
TripleDESCryptoServiceProvider cryptic = GetCryptoProvider();
stream = File.Open(this.GetFullFileNameForUser(securityContext.User, applicationName), FileMode.Create);
crStream = new CryptoStream(stream,
cryptic.CreateEncryptor(), CryptoStreamMode.Write);
BinaryFormatter bFormatter = new BinaryFormatter();
bFormatter.Serialize(crStream, securityContext);
}
catch(Exception)
{
throw;
}
finally
{
if (crStream != null)
crStream.Close();
}
}
}
public SecurityContextDTO RetrieveFromFile(UserDTO user,string applicationName)
{
SecurityContextDTO objectToSerialize;
Stream stream = null;
CryptoStream crStream=null;
try
{
stream = File.Open(this.GetFullFileNameForUser(user, applicationName), FileMode.Open);
crStream= new CryptoStream(stream,
GetCryptoProvider().CreateDecryptor(), CryptoStreamMode.Read);
BinaryFormatter bFormatter = new BinaryFormatter();
//Exception here
objectToSerialize = (SecurityContextDTO)bFormatter.Deserialize(crStream);
}
catch (Exception)
{
objectToSerialize = null;
}
finally
{
if (crStream!=null)
crStream.Close();
}
return objectToSerialize;
}
private static TripleDESCryptoServiceProvider GetCryptoProvider()
{
TripleDESCryptoServiceProvider cryptic = new TripleDESCryptoServiceProvider();
try
{
cryptic.Key = ASCIIEncoding.ASCII.GetBytes(CrypKey);
Rfc2898DeriveBytes db = new Rfc2898DeriveBytes("sdddsdsd", 8);
cryptic.IV = db.GetBytes(8);
}
catch (Exception)
{
throw;
}
finally
{
cryptic.Dispose();
}
return cryptic;
}
Encrypting and writing works fine, the file appears on the disk and the content is there (encrypted of course). But when I call the retrieve method I always get a SerializationException
Binary stream '30' does not contain a valid BinaryHeader. Possible causes are invalid stream or object version change between serialization and deserialization.
When I leave the cryptographic methods out everything works fine.

So,
You realize that in this code
private static TripleDESCryptoServiceProvider GetCryptoProvider()
{
TripleDESCryptoServiceProvider cryptic = new TripleDESCryptoServiceProvider();
try
{
cryptic.Key = ASCIIEncoding.ASCII.GetBytes(CrypKey);
Rfc2898DeriveBytes db = new Rfc2898DeriveBytes("sdddsdsd", 8);
cryptic.IV = db.GetBytes(8);
}
catch (Exception)
{
throw;
}
finally
{
cryptic.Dispose(); // <------- Don't do this until you are done decrypting.
}
return cryptic;
}
you will ALWAYS dispose of the provider meaning you are always using a random key and iv

You are close. However, the stream you pass into the creation of CryptoStream is always, always, always the buffer that will hold your end result. It is not the stream that holds the data you want to encrypt or decrypt. I put the emphasis in there because I remember learning this for the first time and I did exactly what you were doing. So here:
// this is for encryption
var memStreamEncryptedData = new MemoryStream();
var encryptStream = new CryptoStream(memStreamEncryptedData,
transform, CryptoStreamMode.Write);
// this is for decryption
var memStreamDecryptedData = new MemoryStream();
var decryptStream = new CryptoStream(memStreamDecryptedData,
transform, CryptoStreamMode.Write);
Notice in both cases, CryptoStream is being initialized with a blank output stream. Your stream does not enter into the picture until later. So, during a write, you will do the following:
encryptStream.Write(dataToBeEncrypted);
encryptStream.FlushFinalBlock();
encryptStream.Close();
// memStreamEncryptedData now safely holds your encrypted data
And during the read, you will:
decryptStream.Write(dataToBeDecrypted);
encryptStream.FlushFinalBlock();
encryptStream.Close();
// memStreamDecryptedData now safely holds your decrypted data
So, to save you some trouble, here's a nice simple Symmetric method that will perform both encryption and decryption. The only difference between this and yours is that I am working directly on byte arrays, but perhaps that augmentation can be an exercise:
public static byte[] Symmetric(bool encrypt, byte[] plaintext, string ikey)
{
if (plaintext.Length == 0) return plaintext;
// setting up the services can be very expensive, so I'll cache them
// into a static dictionary.
SymmetricSetup setup;
if (!_dictSymmetricSetup.TryGetValue(ikey, out setup))
{
setup = new SymmetricSetup();
setup.des = new DESCryptoServiceProvider { Mode = CipherMode.CBC,
Padding = PaddingMode.Zeros };
setup.hash = Hash(Encoding.ASCII.GetBytes(ikey));
setup.key = setup.hash.ForceLength(8, 0);
setup.IV = Encoding.ASCII.GetBytes("init vec");
setup.des.Key = setup.key;
setup.des.IV = setup.IV;
setup.encrypt = setup.des.CreateEncryptor(setup.des.Key, setup.des.IV);
setup.decrypt = setup.des.CreateDecryptor(setup.des.Key, setup.des.IV);
_dictSymmetricSetup[ikey] = setup;
}
var transform = encrypt ? setup.encrypt : setup.decrypt;
var memStreamEncryptedData = new MemoryStream();
var encStream = new CryptoStream(memStreamEncryptedData, transform, CryptoStreamMode.Write);
if (encrypt)
encStream.Write(new[] {(byte) ((8 - (plaintext.Length + 1)%8)%8)}, 0, 1);
encStream.Write(plaintext, 0, plaintext.Length);
encStream.FlushFinalBlock();
encStream.Close();
memStreamEncryptedData.Flush();
var ciphertext = memStreamEncryptedData.ToArray();
byte b;
if (!encrypt)
if (byte.TryParse("" + ciphertext[0], out b))
ciphertext = ciphertext.Skip(1).Take(ciphertext.Length - b - 1).ToArray();
return ciphertext;
}
And to call it, you might do something like this:
static public byte[] DecryptData(this byte[] source, string password) {
return Symmetric(false, source, password);
}
static public byte[] EncryptData(this byte[] source, string password) {
return Symmetric(true, source, password);
}
Again, you'll do something slightly different to work with streams, but hopefully you get the gist. Instead of MemoryStream, it will be whatever stream you need to feed into your serializer.

Some previous posts that can be of use:
How do I encrypt a string in vb.net using RijndaelManaged, and using PKCS5 padding?
Does BinaryFormatter apply any compression?
In later, you can see how I stacked compression with encryption with serialization. And it works.