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Base 64 decoding of unknown format

I need an advice on decoding base64. I will be doing it in c#.
The thing is, I don't know what type of format the decoding will output it may be text, XML, images or PDF. I only have the base64 encoded string.
How do you guys advice me to proceed? Any suggestions?

Many image types and pdfs include a magic number, where the first X bytes identify the file type. You should decode the string and examine the binary for these (https://asecuritysite.com/forensics/magic gives a list of them). If you still can't identify it check whether it parses as XML using an XML parser else assume it's text.

Extract the MIME type from a base64 string:
/**
* Extract the MIME type from a base64 string
* #param encoded Base64 string
* #return MIME type string
*/
private static String extractMimeType(final String encoded) {
final Pattern mime = Pattern.compile("^data:([a-zA-Z0-9]+/[a-zA-Z0-9]+).*,.*");
final Matcher matcher = mime.matcher(encoded);
if (!matcher.find())
return "";
return matcher.group(1).toLowerCase();
}
Usage:
final String encoded = "data:image/png;base64,iVBORw0KGgoAA...5CYII=";
extractMimeType(encoded); // "image/png"
extractMimeType("garbage"); // ""
Then you can write your byte array:
var filePath = System.IO.Path.Combine(folderPath, string.Format("pdf_{0}.pdf", Guid.NewGuid()));
var byteArray = Convert.FromBase64String(base64pdf);
File.WriteAllBytes(filePath, byteArray);
And open you file:
Device.OpenUri(new Uri("file://" + filePath));
Or tokenize the data since the 64 encoded data look like this "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAoAAAAKAC" and parse that string.

Transforming string to UTF8

I have a string that I receive from email via C# and I want to display it in a correct format. I know the encoding in coming in as Encoding.Default, According to this answer I have to convert it to utf8, So I tried this code:
byte[] bytes = Encoding.Default.GetBytes(input);
string strResult = Encoding.UTF8.GetString(bytes);
It works, but it can't convert some characters:
Actually in web mail interface Original string is:
باسلام همکار گرامی شماره 53018 مربوط به دبیرخانه ستاد می باشد لطفا اصلاح فرمائید
When I convert the string with the code I give this result:
باس �?ا�? �?�?�?ار گرا�?�? �?ا�?�? ش�?ار�? 53018 �?رب�?ط ب�? د ب�?رخا�?�? ستاد �?�? باشد �?طفا اص�?اح فر�?ائ�?د�?
Any idea?
Update:
PS: The content of the input variable:
اÙزاÙØ´ تسÙÙÙات \r\n \r\n\r\n باس Ùا٠ÙÙÙار گراÙÙ ÙاÙÙ Ø´ÙارÙ

Finally solved the problem (+), As you know UTF-8 code unit values have been stored as a sequence of 16-bit code units in a C# string, So we should verify that each code unit is within the range of a byte, First we should copy those values into bytes and then convert the new UTF-8 byte sequence into UTF-16:
byte[] utf8Bytes = new byte[utf8String.Length];
for (int i=0;i<utf8String.Length;++i) {
utf8Bytes[i] = (byte)utf8String[i];
}
var result = Encoding.UTF8.GetString(utf8Bytes,0,utf8Bytes.Length);
So for this input:
اÙزاÙØ´ تسÙÙÙات \r\n\r\n\r\n<p>باسÙا٠ÙÙÙار گراÙÙ ÙاÙÙ Ø´Ùار٠53018 ÙربÙØ· ب٠د بÙرخاÙ٠ستاد Ù٠باشد ÙØ·Ùا اصÙاح ÙرÙائÙد\r\n\r\n
I get the correct result:
افزايش تسهيلات \r\n\r\n\r\n<p>باسلام همكار گرامي نامه شماره 53018 مربوط به د بيرخانه ستاد مي باشد لطفا اصلاح فرمائيد\r\n\r\n \r\n\r\n
PS: for removing extra characters I use this code:
result = result.Replace('\r', ' ').Replace('\n', ' ').ToString();

Understand how to decode this base64 encoded string

I've handled base64 encoded images and strings and have been able to decode them using C# in the past.
I'm now trying on what looks to me like a base64 string, but the value I'm getting is about 98% accurate and I just don't understand what is affecting the output.
Here is the string:
http://pastebin.com/ntcth6uN
And this is the decoded value:
http://pastebin.com/Buh4xXDA
That IS what it should be, but you can clearly see where there are artifacts and the decoded value isn't quite right.
Any idea why it's failing?
var data = Convert.FromBase64String(Faces[i].InfoData);
Faces[i].InfoData = Encoding.UTF8.GetString(data);
Thanks for your help.

The string is not encoded as UTF8, but instead as another encoding. Thus the same encoding must be used to decode it.
Use the following to decode it:
Encoding.ASCII.GetString(data);
If ASCII isn't the correct encoding, here's some code that will iterate through available encodings and list the first 200 characters in order to manually select original encoding:
String encStr = "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";
var data = Convert.FromBase64String(encStr);
// Iterate over all encodings, and decode
foreach (EncodingInfo ei in Encoding.GetEncodings())
{
Encoding e = ei.GetEncoding();
Console.Write("{0,-15} - {1}{2}", ei.CodePage, e.EncodingName, System.Environment.NewLine);
Console.WriteLine(e.GetString(data).Substring(0, 200));
Console.Write(System.Environment.NewLine + "---------------------" + System.Environment.NewLine);
}
Fiddle: https://dotnetfiddle.net/LcV5s8

MVC Convert Base64 String to Image, but ... System.FormatException

My controller is getting an uploaded image in the request object in this code:
[HttpPost]
public string Upload()
{
string fileName = Request.Form["FileName"];
string description = Request.Form["Description"];
string image = Request.Form["Image"];
return fileName;
}
The value of image (at least the beginning of it) looks a lot like this:
data:image/jpeg;base64,/9j/4AAQSkZJRgABAgEAYABgAAD/7gAOQWRvYmUAZAAAAAAB/...
I tried to convert using the following:
byte[] bImage = Convert.FromBase64String(image);
However, that gives the System.FormatException: "The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters."
I get the feeling that the problem is that at least the start of the string isn't base64, but for all I know none of it is. Do I need to parse the string before decoding it? Am I missing something completely different?

It looks like you may just be able to strip out the "data:image/jpeg;base64," part from the start. For example:
const string ExpectedImagePrefix = "data:image/jpeg;base64,";
...
if (image.StartsWith(ExpectedImagePrefix))
{
string base64 = image.Substring(ExpectedImagePrefix.Length);
byte[] data = Convert.FromBase64String(base64);
// Use the data
}
else
{
// Not in the expected format
}
Of course you may want to make this somewhat less JPEG-specific, but I'd try that as a very first pass.

The reason really is "data:image/jpeg;base64,", I'll suggest using this method for removing starting string from base64
var base64Content = image.Split(',')[1];
byte[] bImage = Convert.FromBase64String(base64Content);
This is Shortest solution and you don't have to use magic strings, or write a regex.

Bit Array to String and back to Bit Array

Possible Duplicate Converting byte array to string and back again in C#
I am using Huffman Coding for compression and decompression of some text from here
The code in there builds a huffman tree to use it for encoding and decoding. Everything works fine when I use the code directly.
For my situation, i need to get the compressed content, store it and decompress it when ever need.
The output from the encoder and the input to the decoder are BitArray.
When I tried convert this BitArray to String and back to BitArray and decode it using the following code, I get a weird answer.
Tree huffmanTree = new Tree();
huffmanTree.Build(input);
string input = Console.ReadLine();
BitArray encoded = huffmanTree.Encode(input);
// Print the bits
Console.Write("Encoded Bits: ");
foreach (bool bit in encoded)
{
Console.Write((bit ? 1 : 0) + "");
}
Console.WriteLine();
// Convert the bit array to bytes
Byte[] e = new Byte[(encoded.Length / 8 + (encoded.Length % 8 == 0 ? 0 : 1))];
encoded.CopyTo(e, 0);
// Convert the bytes to string
string output = Encoding.UTF8.GetString(e);
// Convert string back to bytes
e = new Byte[d.Length];
e = Encoding.UTF8.GetBytes(d);
// Convert bytes back to bit array
BitArray todecode = new BitArray(e);
string decoded = huffmanTree.Decode(todecode);
Console.WriteLine("Decoded: " + decoded);
Console.ReadLine();
The Output of Original code from the tutorial is:
The Output of My Code is:
Where am I wrong friends? Help me, Thanks in advance.

You cannot stuff arbitrary bytes into a string. That concept is just undefined. Conversions happen using Encoding.
string output = Encoding.UTF8.GetString(e);
e is just binary garbage at this point, it is not a UTF8 string. So calling UTF8 methods on it does not make sense.
Solution: Don't convert and back-convert to/from string. This does not round-trip. Why are you doing that in the first place? If you need a string use a round-trippable format like base-64 or base-85.

I'm pretty sure Encoding doesn't roundtrip - that is you can't encode an arbitrary sequence of bytes to a string, and then use the same Encoding to get bytes back and always expect them to be the same.
If you want to be able to roundtrip from your raw bytes to string and back to the same raw bytes, you'd need to use base64 encoding e.g.
http://blogs.microsoft.co.il/blogs/mneiter/archive/2009/03/22/how-to-encoding-and-decoding-base64-strings-in-c.aspx