Develop Reference

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);
}

C# GZipStream suddenly not working

I was using GZipStream for some time without any problems. I didn't change any code at my function but now the compress and decompress doesn't work. I have extracted the following simple example (maybe I do something wrong generally...).
public static class ZipLib
{
#region Public Methods
public static string Unzip(byte[] compressedText)
{
try {
byte[] gzBuffer = compressedText;
int msgLength = BitConverter.ToInt32(gzBuffer, 0);
byte[] buffer = new byte[msgLength];
using (MemoryStream ms = new MemoryStream()) {
ms.Write(gzBuffer, 4, gzBuffer.Length - 4);
using (GZipStream zip = new GZipStream(ms, CompressionMode.Decompress, true)) {
zip.Read(buffer, 0, buffer.Length);
}
}
return Encoding.UTF8.GetString(buffer);
}
catch (Exception ex) {
Debug.WriteLine(ex.Message);
}
return "";
}
public static byte[] Zip(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;
byte[] compressed = new byte[ms.Length];
ms.Read(compressed, 0, compressed.Length);
byte[] gzBuffer = new byte[compressed.Length + 4];
Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length);
Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4);
return gzBuffer;
}
#endregion
}
internal class Program
{
#region Private Methods
private static void Main(string[] args)
{
string uncompressedIn = "Hallo Welt";
var compressed = ZipLib.Zip(uncompressedIn);
var uncompressed = ZipLib.Unzip(compressed);
Console.WriteLine("Uncompressed Input: " + uncompressedIn);
Console.WriteLine("Compressed value: " + string.Join(" | ", compressed));
Console.WriteLine("Uncompressed from compressed: " + string.Join(" | ", uncompressed.ToCharArray()));
Console.ReadKey();
}
#endregion
}
The value of uncompressed is "\0\0\0\0"...

In Unzip, you Write to a MemoryStream, then give it to the GZipStream to read from, but: it is still at the end of the stream, you didn't rewind it. Try adding:
ms.Position = 0;
after the Write. Note, however, that it might be more efficient to do:
using(MemoryStream ms = new MemoryStream(gzBuffer, 4, gzBuffer.Length - 4))
{
//...
}
this avoids duplicating any memory

Does Encrypt and Decrypt work for SQL Server database files using c#?

I was encrypting and decrypting the SQL Server database .mdf and .ldf files after detach and while attaching the decrypted files I was getting the following error message
The header for file 'C:\DB\Test.mdf' is not a valid database file header. The FILE SIZE property is incorrect .
Please find my below C# code I was using for .mdf, the same applies for my .ldf files too
private const int KEY_SIZE_BYTES = 32;
private const int IV_SIZE_BYTES = 16;
private const string DBFILENAME = #"C:\DB\Test.mdf"; ;
public void EncryptandDecrypt()
{
var rand = new Random();
using (var fs = File.Open(DBFILENAME, FileMode.Create, FileAccess.Write, FileShare.None))
{
byte[] buffer = new byte[10000];
for (int i = 0; i < 100; ++i)
{
rand.NextBytes(buffer);
fs.Write(buffer, 0, buffer.Length);
}
}
string key = GenerateRandomKey();
Encrypt(DBFILENAME, #"C:\DB\temp\Test.mdf", key);
Decrypt(#"C:\DB\temp\Test.mdf", DBFILENAME, key);
}
public string GenerateRandomKey()
{
byte[] key = new byte[KEY_SIZE_BYTES];
using (var rng = RandomNumberGenerator.Create())
{
rng.GetBytes(key);
}
return Convert.ToBase64String(key);
}
public void Encrypt(string inputFile, string outputFile, string key)
{
const int BUFFER_SIZE = 8192;
byte[] buffer = new byte[BUFFER_SIZE];
byte[] keyBytes = Convert.FromBase64String(key);
byte[] ivBytes = new byte[IV_SIZE_BYTES];
using (var rng = RandomNumberGenerator.Create())
{
rng.GetBytes(ivBytes);
}
using (var inputStream = File.Open(inputFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
using (var outputStream = File.Open(outputFile, FileMode.Create, FileAccess.Write, FileShare.None))
{
outputStream.Write(ivBytes, 0, ivBytes.Length);
using (var cryptoAlgo = Aes.Create())
{
using (var encryptor = cryptoAlgo.CreateEncryptor(keyBytes, ivBytes))
{
using (var cryptoStream = new CryptoStream(outputStream, encryptor, CryptoStreamMode.Write))
{
int count;
while ((count = inputStream.Read(buffer, 0, buffer.Length)) > 0)
{
cryptoStream.Write(buffer, 0, count);
}
}
}
}
}
}
}
public void Decrypt(string inputFile, string outputFile, string key)
{
const int BUFFER_SIZE = 8192;
byte[] buffer = new byte[BUFFER_SIZE];
byte[] keyBytes = Convert.FromBase64String(key);
byte[] ivBytes = new byte[IV_SIZE_BYTES];
using (var inputStream = File.Open(inputFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
inputStream.Read(ivBytes, 0, ivBytes.Length);
using (var outputStream = File.Open(outputFile, FileMode.Create, FileAccess.Write, FileShare.None))
{
using (var cryptoAlgo = Aes.Create())
{
using (var decryptor = cryptoAlgo.CreateDecryptor(keyBytes, ivBytes))
{
using (var cryptoStream = new CryptoStream(inputStream, decryptor, CryptoStreamMode.Read))
{
int count;
while ((count = cryptoStream.Read(buffer, 0, buffer.Length)) > 0)
{
outputStream.Write(buffer, 0, count);
}
}
}
}
}
}
}

I have tested this code and it was ok. I think you probably get the wrong file from temp folder or something like that for header exception. if you get the access error when you're putting back the file then you have to set the proper permissions for the decrypted file.
Also you need to remove the following code from your EncryptDecrypt method and test a real database file:
var rand = new Random();
using (var fs = File.Open(DBFILENAME, FileMode.Create, FileAccess.Write, FileShare.None))
{
byte[] buffer = new byte[10000];
for (int i = 0; i < 100; ++i)
{
rand.NextBytes(buffer);
fs.Write(buffer, 0, buffer.Length);
}
}
It makes a dummy file that server can not read.

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();
}

Get rid of CA2202

How can I get rid of the CA2202 warning (CA2202 : Microsoft.Usage : Object 'compressedStream' can be disposed more than once in method 'Compression.InternalDecompress(byte[])'. To avoid generating a System.ObjectDisposedException you should not call Dispose more than one time on an object) from the following code:
using (var compressedStream = new MemoryStream(inputData))
using (var zipStream = new GZipStream(compressedStream, CompressionMode.Decompress))
using (var resultStream = new MemoryStream())
{
zipStream.CopyTo(resultStream);
return resultStream.ToArray();
}
I have tried getting rid of the "using" statement and replacing it with try/finally pattern but then I get CA2000 (CA2000 : Microsoft.Reliability : In method 'Compression.InternalDecompress(byte[])', call System.IDisposable.Dispose on object 'stream' before all references to it are out of scope). I have tried replacing the above code like this:
MemoryStream decompressedData = null;
MemoryStream stream = null;
GZipStream decompressor = null;
try
{
decompressedData = new MemoryStream();
stream = new MemoryStream(inputData);
decompressor = new GZipStream(stream, CompressionMode.Decompress, false);
stream = null;
int bytesRead = 1;
int chunkSize = 4096;
byte[] chunk = new byte[chunkSize];
while ((bytesRead = decompressor.Read(chunk, 0, chunkSize)) > 0)
{
decompressedData.Write(chunk, 0, bytesRead);
}
decompressor = null;
return decompressedData.ToArray();
}
finally
{
if (stream != null)
{
stream.Dispose();
}
if (decompressor != null)
{
decompressor.Dispose();
}
if (decompressedData != null)
{
decompressedData.Dispose();
}
}

This is what i use:
public class Compression
{
public Compression()
{
}
public byte[] Compress(byte[] buffer)
{
byte[] gzBuffer;
using (MemoryStream ms = new MemoryStream())
{
using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress, true))
{
zip.Write(buffer, 0, buffer.Length);
zip.Close();
}
ms.Position = 0;
MemoryStream outStream = new MemoryStream();
byte[] compressed = new byte[ms.Length];
ms.Read(compressed, 0, compressed.Length);
gzBuffer = new byte[compressed.Length + 4];
Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length);
Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4);
}
return gzBuffer;
}
public byte[] Decompress(byte[] gzBuffer)
{
byte[] buffer;
using (MemoryStream ms = new MemoryStream())
{
int msgLength = BitConverter.ToInt32(gzBuffer, 0);
ms.Write(gzBuffer, 4, gzBuffer.Length - 4);
buffer = new byte[msgLength];
ms.Position = 0;
using (GZipStream zip = new GZipStream(ms, CompressionMode.Decompress))
{
zip.Read(buffer, 0, buffer.Length);
}
}
return buffer;
}
}
Or you can just add a pragma statement to your class
#pragma warning disable 2202
namespace Your.Namespace
{
...
}
#pragma warning restore 2202

This is what I ended up using - gets rid of both CA2000 and CA2202:
private static MemoryStream GetMemoryStream()
{
return new MemoryStream();
}
private static byte[] InternalDecompress(byte[] inputData)
{
Debug.Assert(inputData != null, "inputData cannot be null");
MemoryStream decompressedData = GetMemoryStream();
MemoryStream inputDataMemoryStream = GetMemoryStream();
GZipStream decompressor = null;
try
{
inputDataMemoryStream.Write(inputData, 0, inputData.Length);
inputDataMemoryStream.Position = 0;
decompressor = new GZipStream(inputDataMemoryStream, CompressionMode.Decompress, false);
int bytesRead;
int chunkSize = 4096;
byte[] chunk = new byte[chunkSize];
while ((bytesRead = decompressor.Read(chunk, 0, chunkSize)) > 0)
{
decompressedData.Write(chunk, 0, bytesRead);
}
}
finally
{
if (decompressor != null)
{
decompressor.Dispose();
}
}
return decompressedData.ToArray();
}

This is my attempt. It works and it avoids CA2202
/// <summary>
/// Compresses byte array to new byte array.
/// </summary>
public byte[] Compress(byte[] raw)
{
MemoryStream outStream = null;
GZipStream tinyStream = null;
byte[] retValue = null;
try
{
outStream = new MemoryStream();
tinyStream = new GZipStream(outStream, CompressionMode.Compress);
using (var mStream = new MemoryStream(raw))
mStream.CopyTo(tinyStream);
}
finally
{
if (tinyStream != null)
{
tinyStream.Dispose();
retValue = outStream.ToArray();
}
else if (outStream != null)
{
retValue = outStream.ToArray();
outStream.Dispose();
}
}
return retValue;
}