I have this code in Java, how can I write it with dart?
I need to write some String to a Socket, but before it, I need to write the length of this string. So I use the ByteBuffer class to create some byte array with the string length, and after that I concatenate this two byte arrays. Thank you.
public void writeUTF(String s, OutputStream out) throws IOException {
if (s != null) {
ByteArrayOutputStream bytArray = new ByteArrayOutputStream();
int length = s.getBytes("UTF-8").length;
// Create buffer
byte[] bytesMessageLenght = ByteBuffer.allocate(4).putInt(length).array();
byte[] bytes = s.getBytes();
bytArray.write(bytesMessageLenght);
bytArray.write(bytes);
// Write
out.write(bytArray.toByteArray());
out.flush();
}
}
Use a Dart ByteData which allows you to set the length directly, and then use asUint8List to make a byte array to copy in the rest.
Uint8List encode(String s) {
var encodedString = utf8.encode(s);
var encodedLength = encodedString.length;
var data = ByteData(encodedLength + 4);
data.setUint32(0, encodedLength, Endian.big);
var bytes = data.buffer.asUint8List();
bytes.setRange(4, encodedLength + 4, encodedString);
return bytes;
}
Related
I am integrating a signed hash in an original PDF, and I still have an error on the validity of the signature. it's say that a pdf has been changed after signing.
below the steps: I calculate the hash then I send it for signature and finally I get the hash sign and I proceed to the integration in the original pdf
package com.example.hashdocument;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.*;
import com.itextpdf.text.pdf.security.*;
import com.lexpersona.commons.utils.ProcessLauncher;
import java.io.*;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.util.*;
public class Test2 {
private static final String SRC = "B:/Hash-et-Reconstitution/tmp/Doc_test.pdf";
private static final String DST = "B:/Hash-et-Reconstitution/tmp/Doc_test_DST.pdf";
private static final String HASH = "B:/Hash-et-Reconstitution/tmp/Doc_test_hashed.hash";
private static final String PATH_BAT = "C:/Repo_LP7/lpcommand.bat";
private static final String PIN = "123456";
private static final String CERTIFICATE = "C:/lp7command/tools/certificate.p12";
private static final String SIGNED_HASH = "B:/Hash-et-Reconstitution/tmp/doc_signed.hash";
private static byte[] readFileToByteArray(File file){
FileInputStream fis = null;
byte[] bArray = new byte[(int) file.length()];
try{
fis = new FileInputStream(file);
fis.read(bArray);
fis.close();
}catch(IOException ioExp){
ioExp.printStackTrace();
}
return bArray;
}
public static File bytesToFile(byte[] fileByte,String pathFile) {
File file = new File(pathFile);
try {
OutputStream os = new FileOutputStream(file);
os.write(fileByte);
os.close();
} catch (Exception e) {
e.printStackTrace();
}
return file;
}
public static byte[] signDocument() throws IOException {
ProcessLauncher p = new ProcessLauncher(System.out, System.err);
int exec;
exec = p.exec("cmd.exe /c "+PATH_BAT+" <nul "+ SIGNED_HASH +" "+ PIN+" "
+ HASH+" "+CERTIFICATE, null, null);
byte[] signedHash = readFileToByteArray(new File(SIGNED_HASH));
return signedHash;
}
public static void main(String[] args) throws IOException, GeneralSecurityException, DocumentException {
PdfSignatureAppearance appearance = null;
ByteArrayOutputStream os = null;
String hash_document = "";
InputStream data = null;
int contentEstimated = 8192;
PdfReader reader = new PdfReader(SRC);
reader.unethicalreading = true;
reader.setAppendable(true);
int pdfPagenumber = 1;
pdfPagenumber = reader.getNumberOfPages(); // Sign on last page
os = new ByteArrayOutputStream ();
PdfStamper stamper = PdfStamper.createSignature(reader, os, '\0', null, true);
Calendar cal = Calendar.getInstance();
appearance = stamper.getSignatureAppearance();
appearance.setSignDate(cal);
//appearance.setAcro6Layers(false);
appearance.setReason("Signature de contrat");
appearance.setLocation("MAROC");
appearance.setImage(null);
appearance.setCertificationLevel(PdfSignatureAppearance.CERTIFIED_NO_CHANGES_ALLOWED);
Rectangle rect = new Rectangle(300, 300, 20, 20);
appearance.setVisibleSignature(rect, pdfPagenumber, null);
HashMap<PdfName, Integer> exc = new HashMap<PdfName, Integer>();
exc.put(PdfName.CONTENTS, new Integer(contentEstimated * 2 + 2));
PdfSignature dic = new PdfSignature(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
dic.setReason(appearance.getReason());
dic.setLocation(appearance.getLocation());
dic.setContact(appearance.getContact());
dic.setDate(new PdfDate(appearance.getSignDate()));
appearance.setCryptoDictionary(dic);
appearance.preClose(exc);
data = appearance.getRangeStream();
MessageDigest messageDigest;
String provider = null;
String hashAlgorithm = DigestAlgorithms.SHA256;
if (provider == null){
messageDigest = MessageDigest.getInstance(hashAlgorithm);
}else {
messageDigest = MessageDigest.getInstance(hashAlgorithm,provider);
}
int read = 0;
byte[] buff = new byte[contentEstimated];
while ((read = data.read(buff, 0, contentEstimated)) > 0)
{
messageDigest.update(buff,0,read);
}
byte[] hashDigest = messageDigest.digest();
byte[] documentHash = org.bouncycastle.util.encoders.Hex.encode(hashDigest);
//eSign Start
hash_document = new String(documentHash, "UTF-8");
System.out.println("Document Hash :"+hash_document);
PrintStream out = new PrintStream(new FileOutputStream(HASH));
out.print(hash_document);
byte[] hashdocumentByte = signDocument();
//////////////////// ADD SIGNED BYTES/HASH TO PDF DOCUMENT.
int contentEstimated2 = 8192;
byte[] paddedSig = new byte[contentEstimated2];
byte[] signedDocByte = hashdocumentByte;
System.arraycopy(signedDocByte, 0, paddedSig, 0, signedDocByte.length);
PdfDictionary dic2 = new PdfDictionary();
dic2.put(PdfName.CONTENTS, new PdfString(paddedSig).setHexWriting(true));
appearance.close(dic2);
try(OutputStream outputStream = new FileOutputStream(DST)) {
os.writeTo(outputStream);
}
os.close();
}
}
what do you think abous this code : First i calculate the hash and send to server A for signature
PdfReader reader = new PdfReader(SRC);
FileOutputStream os = new FileOutputStream(TEMP);
PdfStamper stamper = PdfStamper.createSignature(reader, os, '\0');
PdfSignatureAppearance appearance = stamper.getSignatureAppearance();
appearance.setVisibleSignature(new Rectangle(36, 748, 144, 780), 1, "sig");
//appearance.setCertificate(chain[0]);
ExternalSignatureContainer external = new
ExternalBlankSignatureContainer(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
MakeSignature.signExternalContainer(appearance, external, 8192);
InputStream inp = appearance.getRangeStream();
BouncyCastleDigest digest = new BouncyCastleDigest();
byte[] hash = DigestAlgorithms.digest(inp, digest.getMessageDigest("SHA256"));
System.out.println("hash to sign : "+ hash);
bytesToFile(hash, HASH);
byte[] hashdocumentByte = TEST.signed_hash(hash);
PdfReader reader2 = new PdfReader(TEMP);
FileOutputStream os2 = new FileOutputStream(DEST);
ExternalSignatureContainer external2 = new
MyExternalSignatureContainer(hashdocumentByte,null);
MakeSignature.signDeferred(reader2, "sig", os2, external2);
And in the server B where i sign the hash :
BouncyCastleProvider providerBC = new BouncyCastleProvider();
Security.addProvider(providerBC);
// we load our private key from the key store
KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
ks.load(new FileInputStream(CERTIFICATE), PIN);
String alias = (String)ks.aliases().nextElement();
Certificate[] chain = ks.getCertificateChain(alias);
PrivateKey pk = (PrivateKey) ks.getKey(alias, PIN);
PrivateKeySignature signature = new PrivateKeySignature(pk, "SHA256", null);
BouncyCastleDigest digest = new BouncyCastleDigest();
Calendar cal = Calendar.getInstance();
String hashAlgorithm = signature.getHashAlgorithm();
System.out.println(hashAlgorithm);
PdfPKCS7 sgn = new PdfPKCS7(null, chain, "SHA256", null, digest, false);
byte[] sh = sgn.getAuthenticatedAttributeBytes(hash, null, null, CryptoStandard.CMS);
byte[] extSignature = signature.sign(sh);
System.out.println(signature.getEncryptionAlgorithm());
sgn.setExternalDigest(extSignature, null, signature.getEncryptionAlgorithm());
return sgn.getEncodedPKCS7(hash, null, null, null, CryptoStandard.CMS);
Your signDocument method apparently does not accept a pre-calculated hash value but seems to calculate the hash of the data you give it, in your case the (lower case) hex presentation of the hash value you already calculated.
In your first example document you have these values (all hashes are SHA256 hashes):
Hash of the byte ranges to sign:
91A9F5EBC4F2ECEC819898824E00ECD9194C3E85E4410A3EFCF5193ED7739119
Hash of "91a9f5ebc4f2ecec819898824e00ecd9194c3e85e4410a3efcf5193ed7739119".getBytes():
2F37FE82F4F71770C2B33FB8787DE29627D7319EE77C6B5C48152F6E420A3242
Hash value signed by the embedded signature container:
2F37FE82F4F71770C2B33FB8787DE29627D7319EE77C6B5C48152F6E420A3242
And in your first example document you have these values (all hashes also are SHA256 hashes):
Hash of the byte ranges to sign:
79793C58489EB94A17C365445622B7F7945972A5A0BC4C93B6444BEDFFA5A5BB
Hash of "79793c58489eb94a17c365445622b7f7945972a5a0bc4c93b6444bedffa5a5bb".getBytes():
A8BCBC6F9619ECB950864BFDF41D1B5B7CD33D035AF95570C426CF4B0405949B
Hash value signed by the embedded signature container:
A8BCBC6F9619ECB950864BFDF41D1B5B7CD33D035AF95570C426CF4B0405949B
Thus, you have to correct your signDocument method to interpret the data correctly, or you have to give it a byte array containing the whole range stream to digest.
I am trying to read pdf and get the text present in it. Using Nugget iTextSharp -LGPL v4.1.5 . (I am not allowed to use ITextsharp v5.5.13 and it makes life difficult)
private string GetTextFromPage(PdfReader pdfReader, int page)
{
StringBuilder pageText = new StringBuilder();
var cpage = pdfReader.GetPageN(page);
var content = cpage.Get(PdfName.CONTENTS);
//Error for casting Pdfarray to PRIndirectReference
var indirectReference = (PRIndirectReference)content;
}
Getting Exception
System.InvalidCastException : Unable to cast object of type 'iTextSharp.text.pdf.PdfArray' to type 'iTextSharp.text.pdf.PRIndirectReference'.
Kindly suggest how to handle PdfArray object (multiple streams in contents)
I am not too versed in c# but the java code should be easily transferable to c#
I would do it like this:
private byte[] getTextFromPage(PdfReader pdfReader, int page){
PdfDictionary cpage = pdfReader.GetPageN(page);
PdfObject content = cpage.get(PdfName.CONTENTS);
return getContent(content);
}
private byte[] getContent(PdfObject content) throws IOException {
byte[] result=null;
switch (content.type()){
case PdfObject.INDIRECT:
PRIndirectReference ref = (PRIndirectReference) content;
PdfObject directObject = PdfReader.getPdfObject(ref);
result = getContent(directObject);
break;
case PdfObject.ARRAY:
ByteArrayOutputStream baos = new ByteArrayOutputStream();
PdfArray cArray = (PdfArray) content;
for(Object object : cArray.getArrayList()) {
baos.write(getContent((PdfObject) object));
}
result = baos.toByteArray();
break;
case PdfObject.STREAM:
PRStream stream = (PRStream) PdfReader.getPdfObject(content);
result = PdfReader.getStreamBytes(stream);
break;
default:
throw new IllegalStateException("Unsupported content type");
}
return result;
}
But this is only a small step in retrieving the text. You need the whole operator processing, leading, spacing, scaling, font handling etc. So to completely write it from scratch is a big task...
I have two win socket apps, server and client. The server app is at my virtual and client at host machine and the communication is OK. I am sending a ISO file (700MB) through that socket and I came across the error that received bytes are corrupt. When my file come to virtual machine, it has the original size, but the content is not OK. At the client side, I am using this code:
public class ProgramClient
{
public static void StartClient()
{
// Data buffer for incoming data.
byte[] msg;
try
{
IPAddress ipAd = IPAddress.Parse("192.168.137.71");
IPEndPoint remoteEP = new IPEndPoint(ipAd, 1234);
Socket sender = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
sender.Connect(remoteEP);
Console.WriteLine("Client connected to {0}", sender.RemoteEndPoint.ToString());
Console.WriteLine("Sending file...");
msg = GetBinaryFile(#"C:\TCPIP\test_big.iso");
byte[] msgLengthBytes = BitConverter.GetBytes(msg.Length-3);
int msgLength = BitConverter.ToInt32(msgLengthBytes, 0);
Console.WriteLine("int: {0}", msgLength);
Console.WriteLine("msgL size: {0}", msgLengthBytes.Length);
//join arrays, file size info, TCP header
byte[] result = new byte[msgLengthBytes.Length + msgLength];
Buffer.BlockCopy(msgLengthBytes, 0, result, 0, msgLengthBytes.Length);
Buffer.BlockCopy(msg, 3, result, msgLengthBytes.Length, msgLength);
//file extension info, TCP Header
byte extension = 2; //file extension code
byte[] newArray = new byte[result.Length + 1];
result.CopyTo(newArray, 1);
newArray[0] = extension;
result = newArray;
int bytesSent = sender.Send(result);
Console.WriteLine("result size: {0}", result.Length);
sender.Shutdown(SocketShutdown.Both);
sender.Close();
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
catch (ArgumentNullException ane)
{
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
}
catch (SocketException se)
{
Console.WriteLine("SocketException : {0}", se.ToString());
}
catch (Exception e)
{
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
}
private static byte[] GetBinaryFile(string filename)
{
byte[] bytes;
using (FileStream file = new FileStream(filename, FileMode.Open, FileAccess.Read))
{
bytes = new byte[file.Length];
file.Read(bytes, 0, (int)file.Length);
}
return bytes;
}
public static void Main(String[] args)
{
StartClient();
}
}
At the server side I have the following code:
class ProgramServer
{
public static void Main(String[] args)
{
try
{
StartListening();
}
catch (ArgumentNullException ane)
{
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
}
catch (SocketException se)
{
Console.WriteLine("SocketException : {0}", se.ToString());
}
catch (Exception e)
{
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
}
public static void StartListening()
{
byte[] bytes = new Byte[1024];
while (true)
{
string outputPath = string.Empty;
outputPath = #"C:\output\output";
Console.WriteLine("Waiting for a connection...");
Socket handler = SocketInstance().Accept();
data = null;
//for the TCP header, get file extension
bytes = new byte[1];
int bytesReceivedExtension = handler.Receive(bytes);
string extension = GetExtension(bytes[0]);
outputPath = outputPath + extension;
//for the TCP header, get file size information
bytes = new byte[4];
int bytesReceived = handler.Receive(bytes);
int Lenght = BitConverter.ToInt32(bytes, 0);
Console.WriteLine("msg length: " + Lenght);
int TotalReceivedBytes = 0;
while (TotalReceivedBytes < Lenght)
{
bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
TotalReceivedBytes = TotalReceivedBytes + bytesRec;
AppendAllBytes(outputPath, bytes);
}
Console.WriteLine("Bytes received total: " + TotalReceivedBytes);
Console.WriteLine(File.Exists(outputPath) ? "File received." : "File not received.");
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
private static Socket SocketInstance()
{
IPAddress ipAd = IPAddress.Parse("192.168.137.71");
IPEndPoint localEndPoint = new IPEndPoint(ipAd, 1234);
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
listener.Bind(localEndPoint);
listener.Listen(10);
return listener;
}
public static void AppendAllBytes(string path, byte[] bytes)
{
using (var stream = new FileStream(path, FileMode.Append))
{
stream.Write(bytes, 0, bytes.Length);
}
}
public static string GetExtension(byte extOfFile)
{
switch (extOfFile)
{
case 0:
return ".txt";
case 1:
return ".png";
case 2:
return ".iso";
default:
return "";
}
}
}
So, how can I be sure that my byte[] is OK? Because when I open that ISO file at the received side, its content is not OK. IS there some alternative for any type of file to binary conversion?
Thanks.
The framing protocol you made up seems to work like this:
0 1 2 3 4 ... N
[L][L][L][L][D][...][D]
Where L represents an 32-bit integer (in which endianness?) indicating the lenght of the Data.
First, you're sending the wrong file length:
byte[] msgLengthBytes = BitConverter.GetBytes(msg.Length-3);
Why do you subtract 3? You shouldn't. This causes the last 3 bytes to be chopped off the file.
Then when filling the message buffer, you start writing at byte 3, or the last byte of L:
Buffer.BlockCopy(msg, 3, result, msgLengthBytes.Length, msgLength);
This will cause the reader to interpret an incorrect data length. You should start at byte 4.
Third, when writing the file, you shouldn't append the entire buffer, but only the bytes that Receive() actually wrote in the buffer:
bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
TotalReceivedBytes = TotalReceivedBytes + bytesRec;
AppendAllBytes(outputPath, bytes, bytesRec);
Then in that method:
public static void AppendAllBytes(string path, byte[] bytes, int bufferLength)
{
using (var stream = new FileStream(path, FileMode.Append))
{
stream.Write(bytes, 0, bufferLength);
}
}
And this is why you shouldn't write your own protocol and socket code if you don't know very well what you're doing. Leverage existing protocols and libraries instead.
I have a rest service written to receive a file and save it.
The problem is that when I receive more than 2 requests, the files are not written only the last request is taken into consideration and written.
Here is my code:
#POST
#RequestMapping(value = "/media/{mediaName}/{mediaType}")
#Produces(MediaType.APPLICATION_OCTET_STREAM)
#ResponseBody
public String updateResourceLocally(#FormDataParam("rawData") InputStream rawData, #PathVariable("mediaName") String mediaName, #PathVariable("mediaType") String mediaType) {
logger.info("Entering updateResourceLocally for " + jobId + "; for media type: " + mediaType);
final String storeDir = "/tmp/test/" + mediaName + ("/");
final String finalExtension = mediaType;
final InputStream finalRawData = rawData;
// new Thread(new Runnable() {
// public void run() {
// writeToFile(finalRawData, storeDir, finalExtension);
// }
// }).start();
writeToFile(finalRawData, storeDir, finalExtension);
// int poolSize = 100;
// ExecutorService executor = Executors.newFixedThreadPool(poolSize);
// executor.execute(new Runnable() {
// #Override
// public void run() {
// writeToFile(rawData, storeDir, finalExtension);
// }
// });
logger.info("File uploaded to : " + storeDir);
return "Success 200";
}
I tried to put the writeToFile into threads, but still no success. Here is what writeToFile does
public synchronized void writeToFile(InputStream rawData,
String uploadedFileLocation, String extension) {
StringBuilder finalFileName = null;
String currentIncrement = "";
String fileName = "raw";
try {
File file = new File(uploadedFileLocation);
if (!file.exists()) {
file.mkdirs();
}
while (true) {
finalFileName = new StringBuilder(fileName);
if (!currentIncrement.equals("")) {
finalFileName.append("_").append(currentIncrement).append(extension);
}
File f = new File(uploadedFileLocation + finalFileName);
if (f.exists()) {
if (currentIncrement.equals("")) {
currentIncrement = "1";
} else {
currentIncrement = (Integer.parseInt(currentIncrement) + 1) + "";
}
} else {
break;
}
}
int read = 0;
byte[] bytes = new byte[1024];
OutputStream out = new FileOutputStream(new File(uploadedFileLocation + finalFileName));
while ((read = rawData.read(bytes)) != -1) {
out.write(bytes, 0, read);
}
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e.getMessage());
}
}
The writeToFile creates a folder and writes a file, if the file already exists, it appends 1 and then increments the 1 accordingly and writes the file, so I would get raw.zip, raw-1.zip, etc.
I think the inputstream bytes are being lost, am I correct in my assumption?
NOTE: I do not have a UI client, I am using Poster a Firefox extension.
Update: What I am trying to achieve here is very simple
I receive number of requests with files attached
I need to save them. If the mediaName and mediaType are the same, then I need to append something to the filename and save it in the same location
If they are different I do not have a problem
The problem I am facing with the current code is that, when I post multiple time to the same URL, I have file-names created according to what I want, but the file content is not right, they vary depending on when the request came in and only the last POST's request is written properly.
Eg. I have a zip file of size 250MB, when I post 5 time, the 1st four will have random sizes and the 5th will have the complete 250MB, but the previous four should also have the same content.
You must separate the stream copy from the free filename assignation. The stream copy must be done within the calling thread (jersey service). Only the file naming operation must be common to all threads/requests.
Here is your code with a little refactoring :
getNextFilename
This file naming operation must be synchronized to guarantee each call gives a free name. This functions creates an empty file to guarantee the next call to work, because the function relies on file.exists().
public synchronized File getNextFilename(String uploadedFileLocation, String extension)
throws IOException
{
// This function MUST be synchronized to guarantee unicity of files names
// Synchronized functions must be the shortest possible to avoid threads waiting each other.
// No long job such as copying streams here !
String fileName = "raw";
//Create directories (if not already existing)
File dir = new File(uploadedFileLocation);
if (!dir.exists())
dir.mkdirs();
//Search for next free filename (raw.<extension>, else raw_<increment>.<extension>)
int currentIncrement = 0;
String finalFileName = fileName + "." + extension;
File f = new File(uploadedFileLocation + finalFileName);
while (f.exists())
{
currentIncrement++;
finalFileName = fileName + "_" + currentIncrement + "." + extension;
f = new File(uploadedFileLocation + finalFileName);
}
//Creates the file with size 0 in order to physically reserve the file "raw_<n>.extension",
//so the next call to getNextFilename will find it (f.exists) and will return "raw_<n+1>.extension"
f.createNewFile();
//The file exists, let the caller fill it...
return f;
}
writeToFile
Must not be synchronized !
public void writeToFile(InputStream rawData, String uploadedFileLocation, String extension)
throws IOException
{
//(1) Gets next available filename (creates the file with 0 size)
File file = getNextFilename(uploadedFileLocation, extension);
//(2) Copies data from inputStream to file
int read = 0;
byte[] bytes = new byte[1024];
OutputStream out = new FileOutputStream(file);
while ((read = rawData.read(bytes)) != -1) {
out.write(bytes, 0, read);
}
out.flush();
out.close();
}
How I can convert the following methods to C# 2.0?
private static string ToHexString(byte[] bytes)
{
return string.Join(string.Empty, bytes.Select(x => x.ToString("X2")).ToArray());
}
private static byte[] ToByteArray(string hex)
{
return Enumerable.Range(0, hex.Length).
Where(x => 0 == x % 2).
Select(x => Convert.ToByte(hex.Substring(x, 2), 16)).
ToArray();
}
I haven't got experience with .NET 2.0. Thanks!
void Main()
{
string s = ToHexString(new byte[]{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15});
Console.WriteLine(s);
foreach (byte b in ToByteArray(s))
Console.WriteLine(b);
}
private static string ToHexString(byte[] bytes)
{
StringBuilder sb = new StringBuilder();
foreach (byte b in bytes)
sb.Append(b.ToString("X2"));
return sb.ToString();
}
private static byte[] ToByteArray(string hex)
{
byte[] b = new byte[hex.Length/2];
for (int i = 0; i < b.Length; i++)
{
b[i] = Convert.ToByte(hex.Substring(i*2,2), 16);
}
return b;
}
You should be able to do this conversion yourself. Obviously you'll want to convert it into a for loop. Enumerable.Range essentially provides an int[] array upon which to loop. After that, the Where equates to an if check, the Select is a transformation from the int to a substring and finally to a byte, and last, you stuff all that into an array, probably by adding them to a List<byte> declared outside the loop. (and when you're done, you can call ToArray on the list)
I could provide a complete answer, but I think this sort of exercise is best left to you so you can learn from it.