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encode and decode strange .shm file data to and from base64 c#

first a depressing fact: https://www.base64decode.org/ can do what i want to do.
i´m trying to encode and decode (to and from base64) a model file (.shm) generated by the image processing tool MVTec Halcon because i want to store it in a xml file.
If i open it, it has this strange form:
HSTF ÿÿÿÿ¿€ Q¿ÙG®záH?Üä4©±w?­Eè}‰#?ð ................
I´m using this methods to encode and decode it:
public static string Base64Encode(string text)
{
Byte[] textBytes = Encoding.Default.GetBytes(text);
return Convert.ToBase64String(textBytes);
}
public static string Base64Decode(string base64EncodedData)
{
Byte[] base64EncodedBytes = Convert.FromBase64String(base64EncodedData);
return Encoding.Default.GetString(base64EncodedBytes);
}
and calling the methods from a gui like this:
var model = File.ReadAllText(#"C:\Users\\Desktop\model_region_nut.txt");
var base64 = ImageConverter.Base64Encode(model);
File.WriteAllText(#"C:\Users\\Desktop\base64.txt", base64);
var modelneu = ImageConverter.Base64Decode(File.ReadAllText(#"C:\Users\\Desktop\base64.txt"));
File.WriteAllText(#"C:\Users\\Desktop\modelneu.txt", modelneu);
my result for modelneu is:
HSTF ?????? Q??G?z?H???4??w??E?}??#??
so you can see that there are lots of missing characters.. I guess the problem is caused by using .Default.
Thanks for your help,
Michel

If you're working with binary data, there is no reason at all to go through text decoding and encoding. Doing so only risks corrupting the data in various ways, even if you're using a consistent character encoding.
Just use File.ReadAllBytes() instead of File.ReadAllText() and skip the unnecessary Encoding step.

The problem is with reading file with unspecified encoding, check this question.
As mentioned there you can go with overload for ReadAllText to specify encoding and also for writing you must specofy encoding for WriteAllText I suggest using UTF-8 encoding so:
var model = File.ReadAllText(#"C:\Users\pichlerm\Desktop\model_region_nut.txt",Encoding.UTF8);
var base64 = ImageConverter.Base64Encode(model);
File.WriteAllText(#"C:\Users\\Desktop\base64.txt", base64,Encoding.UTF8);
var modelneu = ImageConverter.Base64Decode(File.ReadAllText(#"C:\Users\\Desktop\base64.txt"));
File.WriteAllText(#"C:\Users\pichlerm\Desktop\modelneu.txt", modelneu);

HttpClient: Correct order to detect encoding

I'm using HttpClient to fetch some files. I put the content into a byte array (bytes). Now I need to detect the encoding. The contenttype will be either html, css, JavaScript or XML contenttype.
Currently I check the charset from headers, then check for a BOM (byte order mark) before I finally check the first part of the file for a charset meta tag.
Normally this works fine, because there are no conflicts.
But: Is that order correct (in case of conflict)?
The code I corrently use:
Encoding encoding;
try
{
encoding = Encoding.GetEncoding(responseMessage.Content.Headers.ContentType.CharSet);
}
catch
{
using (MemoryStream ms = new MemoryStream(bytes))
{
using (StreamReader sr = new StreamReader(ms, Encoding.Default, true))
{
char[] chars = new char[1024];
sr.Read(chars, 0, 1024);
string textDefault = new string(chars);
if (sr.CurrentEncoding == Encoding.Default)
{
encoding = Global.EncodingFraContentType(textDefault);
}
else
{
encoding = sr.CurrentEncoding;
}
}
}
}
responseInfo.Text = encoding.GetString(bytes);
Global.EncodingFraContentType is a regular expression that finds the charset defined either in XML declaration, or in a meta tag.
What order is the correct to detect charset/encoding?

The correct answer depends not on order, but on which actually gives the correct result, and there's no perfect answer here.
If there is a conflict, then the server has given you something incorrect. Since it's incorrect there can't be a "correct" order because there isn't a correct way of being incorrect. And, maybe the header and the embedded metadata are both wrong!
No even slightly common-used encoding can have something that looks like a BOM would look like in UTF-8 or UTF-16 at the beginning and still be a valid example of the content types you mention, so if there's a BOM then that wins.
(The one exception to that is if the document is so badly edited as to switch encoding part-way through, which is no unheard of, but then the buggy content is so very buggy as to have no real meaning).
If the content contains no octet that is greater than 0x7F then it doesn't matter and the header and metadata both claim it as different examples of US-ASCII, UTF-8, any of the ISO-8859 family of encodings, or any of the other encodings for which those octets all map to the same code point, then it doesn't really matter which you consider it to be, as the nett result is the same. Consider it to be whatever the metadata says, as then you don't need to rewrite it to match correctly.
If it's in UTF-16 without a BOM it is likely going to be clearly as such very soon as all of those formats have a lot of characters with special meaning in the range U+0000 to U+00FF (indeed, generally U+0020 to U+007F) and so you'll have lots of ranges with a zero byte every other character.
If it has octets above 0x7F and is valid UTF-8, then it's almost certainly UTF-8. (By the same token if it's not UTF-8 and has octets above 0x7F then it almost certainly can't be mistaken for UTF-8).
The trickiest reasonably common case is if you have conflicting claims about it being in two different encodings which are both single-octet-per-character encodings and an octet in the range 0x80-0xFF is present. This is the case that you can't be sure about. If one encoding is a subset of the other (especially when C1 controls are excluded) then you could go for the superset, but that requires storing knowledge about those encodings, and considerable amount of work. Most of the time I'd be inclined to just throw an exception, and when it's found in the logs see if I can get the source to fix their bug, or special-case that source, but that doesn't work if you are dealing with a very large number of disparate sources that you may not have a relationship with. Alas there is no perfect answer here.
Its worth noting also that sometimes both header and embedded metadata will agree with each other incorrectly. A common case is content in CP-1252 but claimed as being in ISO-8859-1.

According to W3C Faq
If you have a UTF-8 byte-order mark (BOM) at the start of your file then recent browser versions other than Internet Explorer 10 or 11 will use that to determine that the encoding of your page is UTF-8. It has a higher precedence than any other declaration, including the HTTP header.
When it comes to the http-header vs meta BOM takes precedence, as long as the meta is within the first 1024 it can take precedence, though there is no strict rule on that.

Conclusion - in order of importance:
Byte Order Mark (BOM): If present, this is AUTHORATIVE, since it was
added by the editor that actually saved the file (this can only be
present on unicode encodings).
Content-Type charset (in header set by the server): For dynamically created/processed files, it should be present (since the
server knows), but might not be for static files (the server just
sends those).
Inline charset: For xml, html and css the encoding can be be specified inside the document, in either xml prolog, html meta tag
or #charset in css. To read that you need to decode the first
part of the document using for instance 'Windows-1252' encoding.
Assume utf-8. This is the standard of the web and is today by far the most used.
If the found encoding equals 'ISO-8859-1', use 'Windows-1252' instead (required in html5 - read more at Wikipedia
Now try to decode the document using the found encoding. If error handling is turned on, that might fail! In that case:
Use 'Windows-1252'. This was the standard in old windows files and works fine as last try (there's still a lot of old files out there).
This will never throw errors. However it might of course be wrong.
I have made a method that implements this. The regex I use is able to find encodings specified as:
Xml: <?xml version="1.0" encoding="utf-8"?> OR <?xml encoding="utf-8"?>
html: <meta charset="utf-8" /> OR <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
css: #charset "utf-8";
(It works with both single and double qoutes).
You will need:
using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
Here's the method that returns the decoded string (parameters are the HttpClient and the Uri):
public static async Task<string> GetString(HttpClient httpClient, Uri url)
{
byte[] bytes;
Encoding encoding = null;
Regex charsetRegex = new Regex(#"(?<=(<meta.*?charset=|^\<\?xml.*?encoding=|^#charset[ ]?)[""']?)[\w-]+?(?=[""';\r\n])",
RegexOptions.IgnoreCase | RegexOptions.CultureInvariant | RegexOptions.ExplicitCapture);
using (HttpResponseMessage responseMessage = await httpClient.GetAsync(url).ConfigureAwait(false))
{
responseMessage.EnsureSuccessStatusCode();
bytes = await responseMessage.Content.ReadAsByteArrayAsync().ConfigureAwait(false);
string headerCharset = responseMessage?.Content?.Headers?.ContentType?.CharSet;
byte[] buffer = new byte[0x1000];
Array.Copy(bytes, buffer, Math.Min(bytes.Length, buffer.Length));
using (MemoryStream ms = new MemoryStream(buffer))
{
using (StreamReader sr = new StreamReader(ms, Encoding.GetEncoding("Windows-1252"), true, buffer.Length, true))
{
string testString = await sr.ReadToEndAsync().ConfigureAwait(false);
if (!sr.CurrentEncoding.Equals(Encoding.GetEncoding("Windows-1252")))
{
encoding = sr.CurrentEncoding;
}
else if (headerCharset != null)
{
encoding = Encoding.GetEncoding(headerCharset, EncoderFallback.ExceptionFallback, DecoderFallback.ExceptionFallback);
}
else
{
string inlineCharset = charsetRegex.Match(testString).Value;
if (!string.IsNullOrEmpty(inlineCharset))
{
encoding = Encoding.GetEncoding(inlineCharset, EncoderFallback.ExceptionFallback, DecoderFallback.ExceptionFallback);
}
else
{
encoding = new UTF8Encoding(false, true);
}
}
if (encoding.Equals(Encoding.GetEncoding("iso-8859-1")))
{
encoding = Encoding.GetEncoding("Windows-1252", EncoderFallback.ExceptionFallback, DecoderFallback.ExceptionFallback);
}
}
}
using (MemoryStream ms = new MemoryStream(bytes))
{
try
{
using (StreamReader sr = new StreamReader(ms, encoding, false, 0x8000, true))
{
return await sr.ReadToEndAsync().ConfigureAwait(false);
}
}
catch (DecoderFallbackException)
{
ms.Position = 0;
using (StreamReader sr = new StreamReader(ms, Encoding.GetEncoding("Windows-1252"), false, 0x8000, true))
{
return await sr.ReadToEndAsync().ConfigureAwait(false);
}
}
}
}
}
You should wrap the method call in a try/catch, since HttpClient can throw errors, if the request fails.
Update:
In .Net Core, you don't have the 'Windows-1252' encoding (big mistake IMHO), so here you must settle with 'ISO-8859-1'.

Change StreamReader Encoding while reading from NetworkStream

I am trying to read an email from POP3 and change to the correct encoding when I find the charset in the headers.
I use a TCP Client to connect to the POP3 server.
Below is my code :
public string ReadToEnd(POP3Client pop3client, out System.Text.Encoding messageEncoding)
{
messageEncoding = TCPStream.CurrentEncoding;
if (EOF)
return ("");
System.Text.StringBuilder sb = new System.Text.StringBuilder(m_bytetotal * 2);
string st = "";
string tmp;
do
{
tmp = TCPStream.ReadLine();
if (tmp == ".")
EOF = true;
else
sb.Append(tmp + "\r\n");
//st += tmp + "\r\n";
m_byteread += tmp.Length + 2; // CRLF discarded by read
FireReceived();
if (tmp.ToLower().Contains("content-type:") && tmp.ToLower().Contains("charset="))
{
try
{
string charSetFound = tmp.Substring(tmp.IndexOf("charset=") + "charset=".Length).Replace("\"", "").Replace(";", "");
var realEnc = System.Text.Encoding.GetEncoding(charSetFound);
if (realEnc != TCPStream.CurrentEncoding)
{
TCPStream = new StreamReader(pop3client.m_tcpClient.GetStream(), realEnc);
}
}
catch { }
}
} while (!EOF);
messageEncoding = TCPStream.CurrentEncoding;
return (sb.ToString());
}
If I remove this line:
TCPStream = new StreamReader(pop3client.m_tcpClient.GetStream(), realEnc);
Everything works fine except that when the e-mail contains different charset characters I get question marks as the initial encoding is ASCII.
Any suggestions on how to change the encoding while reading data from the Network Stream?

You're doing it wrong (tm).
Seriously, though, you are going about trying to solve this problem in completely the wrong way. Don't use a StreamReader for this. And especially don't read 1 byte at a time (as you said you needed to do in a comment on an earlier "solution").
For an explanation of why not to use a StreamReader, besides the obvious "because it isn't designed to switch between encodings during the process of reading", feel free to read over another answer I gave about the inefficiencies of using a StreamReader here: Reading an mbox file in C#
What you need to do is buffer your reads (such as a 4k buffer should be fine). Then, as you are already having to do anyway, scan for the '\n' byte to extract content on a line-by-line basis, combining header lines that were folded.
Each header may have multiple encoded-word tokens which may each be in a separate charset, assuming they are properly encoded, otherwise you'll have to deal with undeclared 8-bit data and try to massage that into unicode somehow (probably by having a set of fallback charsets). I'd recommend trying UTF-8 first followed by a selection of charsets that the user of your library has provided before finally trying iso-8859-1 (make sure not to try iso-8859-1 until you've tried everything else, because any sequence of 8-bit text will convert properly to unicode using the iso-8859-1 character encoding).
When you get to text content of the message, you'll want to check the Content-Type header for a charset parameter. If no charset parameter is defined, it should be US-ASCII, but in practice it could be anything. Even if the charset is defined, it might not match the actual character encoding used in the text body of the message, so once again you'll probably want to have a set of fallbacks.
As you've probably guessed by this point, this is very clearly not a trivial task as it requires the parser to do on-the-fly character conversion as it goes (and the character conversion requires internal parser state about what the expected charset is at any given time).
Since I've already done the work, you should really consider using MimeKit which will parse the email and properly do charset conversion on the headers and the content using the appropriate charset encoding.
I've also written a Pop3Client class that is included in my MailKit library.
If your goal is to learn and write your own library, I'd still highly recommend reading over my code because it is highly efficient and does things in a proper way.

There are some ways you can detect the encoding by looking at the Byte Order Mark, which are the firts few bytes of the stream. These will tell you the encoding. However, the stream might not have a BOM, and in these cases it could be ASCII, UTF without BOM, or others.
You can convert your stream from one encoding to another with the Encoding Class:
Encoding textEncoding = Encoding.[your detected encoding here];
byte[] converted = Encoding.UTF8.GetBytes(textEncoding.GetString(TCPStream.GetBuffer()));
You may select your preferred encoding when converting.
Hope it answers your question.
edit
You may use this code to read your stream in blocks.
MemoryStream st = new MemoryStream();
int numOfBytes = 1024;
int reads = 1;
while (reads > 0)
{
byte[] bytes = new byte[numOfBytes];
reads = yourStream.Read(bytes, 0, numOfBytes);
if (reads > 0)
{
int writes = ( reads < numOfBytes ? reads : numOfBytes);
st.Write(bytes, 0, writes);
}
}

How to encode and decode Broken Chinese/Unicode characters?

I've tried googling around but wasn't able to find what charset that this text below belongs to:
具有éœé›»ç”¢ç”Ÿè£ç½®ä¹‹å½±åƒè¼¸å…¥è£ç½®
But putting <meta http-equiv="Content-Type" Content="text/html; charset=utf-8"> and keeping that string into an HTML file, I was able to view the Chinese characters properly:
具有靜電產生裝置之影像輸入裝置
So my question is:
What tools can I use to detect the character set of this text?
And how do I convert/encode/decode them properly in C#?
Updates:
For completion sake, I've updated this test.
[TestMethod]
public void TestMethod1()
{
string encodedText = "具有éœé›»ç”¢ç”Ÿè£ç½®ä¹‹å½±åƒè¼¸å…¥è£ç½®";
Encoding utf8 = new UTF8Encoding();
Encoding window1252 = Encoding.GetEncoding("Windows-1252");
byte[] postBytes = window1252.GetBytes(encodedText);
string decodedText = utf8.GetString(postBytes);
string actualText = "具有靜電產生裝置之影像輸入裝置";
Assert.AreEqual(actualText, decodedText);
}
}

What is happening when you save the "bad" string in a text file with a meta tag declaring the correct encoding is that your text editor is saving the file with Windows-1252 encoding, but the browser is reading the file and interpreting it as UTF-8. Since the "bad" string is incorrectly decoded UTF-8 bytes with the Windows-1252 encoding, you are reversing the process by encoding the file as Windows-1252 and decoding as UTF-8.
Here's an example:
using System.Text;
using System.Windows.Forms;
namespace Demo
{
class Program
{
static void Main(string[] args)
{
string s = "具有靜電產生裝置之影像輸入裝置"; // Unicode
Encoding Windows1252 = Encoding.GetEncoding("Windows-1252");
Encoding Utf8 = Encoding.UTF8;
byte[] utf8Bytes = Utf8.GetBytes(s); // Unicode -> UTF-8
string badDecode = Windows1252.GetString(utf8Bytes); // Mis-decode as Latin1
MessageBox.Show(badDecode,"Mis-decoded"); // Shows your garbage string.
string goodDecode = Utf8.GetString(utf8Bytes); // Correctly decode as UTF-8
MessageBox.Show(goodDecode, "Correctly decoded");
// Recovering from bad decode...
byte[] originalBytes = Windows1252.GetBytes(badDecode);
goodDecode = Utf8.GetString(originalBytes);
MessageBox.Show(goodDecode, "Re-decoded");
}
}
}
Even with correct decoding, you'll still need a font that supports the characters being displayed. If your default font doesn't support Chinese, you still might not see the correct characters.
The correct thing to do is figure out why the string you have was decoded as Windows-1252 in the first place. Sometimes, though, data in a database is stored incorrectly to begin with and you have to resort to these games to fix the problem.

string test = "敭畳灴獩楫n"; //incoming data. must be mesutpiskin
byte[] bytes = Encoding.Unicode.GetBytes(test);
string s = string.Empty;
for (int i = 0; i < bytes.Length; i++)
{
s += (char)bytes[i];
}
s = s.Trim((char)0);
MessageBox.Show(s);
//s=mesutpiskin

I'm not really sure what you mean, but I'm guessing you want to convert between a string in a certain encoding in byte array form and a string. Let's assume the character encoding is called "FooBar":
This is how you encode and decode:
Encoding myEncoding = Encoding.GetEncoding("FooBar");
string myString = "lala";
byte[] myEncodedBytes = myEncoding.GetBytes(myString);
string myDecodedString = myEncoding.GetString(myEncodedBytes);
You can learn more about the Encoding class over at MSDN.

Answering your question at the end of your post:
If you want to determine the text encoding on runtime you should look at that: http://code.google.com/p/ude/
for converting character sets you can use http://msdn.microsoft.com/en-us/library/system.text.encoding.convert(v=vs.100).aspx

It's Windows Latin 1. I pasted the Chinese text as UTF-8 into BBEDIT (a text editor for Mac) and re-opened the file as Windows Latin 1 and bang, the exact diacritics appeared.

Encoding in Streamreader in my silverlight application

Having trouble geting the encoding right in my silverlight application.
I need support for western europe letters like æ,ø,å,â and so(Latin1??).
But I can't get it right. What should be instead of SOMEENCODINGHERE? did try
Encoding enc = Encoding.GetEncoding("Latin1"); but no names I used as param was recognized =( .
If I use Encoding.Unicode tr.ReadLine() reads the whole file and convert it to Chinese for some reason.
private Dictionary<int, string> InitDictionary()
{
var d = new Dictionary<int, string>();
var sri = App.GetResourceStream(new Uri(fileDic, UriKind.Relative));
using (TextReader tr = new StreamReader(sri.Stream, Encoding.SOMEENCODINGHERE))
{
int i = 0;
string line;
while ((line = tr.ReadLine()) != null)
{
d.Add(i++, line);
}
}
return d;
}

If you really want ISO-Latin-1, you can use
Encoding.GetEncoding(28591);
But the normal Windows Western Europe code page is 1252:
Encoding.GetEncoding(1252);
Are you absolutely sure that's the encoding for your stream though? These days it's more common to use UTF-8. What's generating your text resource?

Silverlight (1-4, don't known about 5) doesn't support ANSI Encodings (codepages). It supports only Unicode encodings: UTF8 and UTF16.
See http://msdn.microsoft.com/en-us/library/system.text.encoding%28VS.95%29.aspx for details.
So suggested Encoding.GetEncoding(1252) and any other codepage numbers do not work.
You have to implement your Encoding class for needed codepage.
If you have found an appropriate implementation please share it, i'd be interesting.