I'm working on a c# project, I created a method that will receive a file as bytes value byte[] parameter.
Method
public static FileEncryptionModel Encrypt(byte[] Filebytes)
{
//Some code here
}
the question is how can I know the file extension just from its bytes?
thank you.
There is no foolproof way to achieve this. Take a look at the list of file signatures here: https://en.m.wikipedia.org/wiki/List_of_file_signatures
As mentioned here: https://en.m.wikipedia.org/wiki/File_format#Magic_number
Originally, this term was used for a specific set of 2-byte identifiers at the beginnings of files, but since any binary sequence can be regarded as a number, any feature of a file format which uniquely distinguishes it can be used for identification.
Your best bet is to store the file type along with the byte array.
You can try the magic number approach, but how could you know an html file from any other text file?
Related
I'm using C# Chilkat library. In this example; I can encrypt the file with public key and open it with private key. But in my scenario there is no physical file for encrypt, at runtime I have byte arrays. And I want to encrypt it with public key and save as a file. Then I want to decrypt it with private key. Is there anyway to do it? I can't find any sample code about this.
It is possible to do that. If you looked over the whole example closely, you will have seen this line:
string encryptedAesKey = rsa2.EncryptStringENC(randomKey,bUsePrivateKey);
Earlier in the program, I saw that randomKey is a string. So that is how you can encrypt strings in memory. The program does not show how to encrypt a byte array, but clicking on the Chillkat.Rsa hyperlink in the program, you will go to this page.
There, you will see the methods available to you. EncryptStringENC is there, the method to encrypt a string and return a string. Note that there are 3 other Encrypt methods there, 2 of which will accept a byte array, one returning an encrypted string and the other an encrypted byte array. You should choose the one among these that meets your requirements.
As for saving the encrypted byte array to file, there are a lot of tutorials on saving to file, so for sake of brevity, I will not go into that here.
I am working on a system that needs to read a binary file containing certain Persian names/stock instruments. I need to convert the binary data into string to be used in further processes. I have googled it and haven't really found a solution to my problem. Anyone here who has worked in such a scenario or knows how to tackle such a problem?
Here is the code that I am using to convert the bytes to string (simple as it maybe):
byte[] data = binaryReader.ReadBytes(amountOfData);
string symbolRead = Encoding.ASCII.GetString(data);
FYI, I have tried to change my system locale to Persian and that hasn't helped either. Although it does allow me to view already written text in Persian.
Hoping to find a solution.
Thanks.
Don't use ASCII for encoding. First try using Default after setting your locale; then try asking directly someone what encoding is most used for Persia, and use this one.
Determine what coding is used in your file and use the corresponding encoding instead of Encoding.ASCII.GetString(...). Possible values could be Encoding.UTF8.GetString(...) or Encoding.Default.GetString(...) to use your system encoding. See documentation of the Encoding class for other possibilities.
I want to create a binary file and store string data in it, I used this sample:
FileStream fs = new FileStream("c:\\test.data", FileMode.Create);
BinaryWriter bw = new BinaryWriter(fs);
bw.Write(Encoding.ASCII.GetBytes("david stein"));
bw.Close();
but when I opened created file by this sample (test.data) in notepad, it has string data in it ("david stein"), now my question is that whats the difference between this binary writing and text writing when the result is string?
I'm looking to create a data in binary file until user can not open and read my data by note pad and if user open it in notepad see real binary data .
in some files when you open theme in text editors you can not read file content like jpg files contents,they do not use any encryption methods,what about it?how can i wite my data like this?
now my question is that whats the difference between this binary writing and text writing when the result is string?
The data in a file is always "a sequence of bytes". In this case, the sequence of bytes you've written is "the bytes representing the text 'david stein'" in the ASCII encoding. So yes, if you open the file in any editor which tries to interpret the bytes as text in a way which is compatible with ASCII, you'll see the text "david stein". Really it's just a load of bytes though - it all depends on how you interpret them.
If you'd written:
File.WriteAllText("c:\\test.data", "david stein", Encoding.ASCII);
you'd have ended up with the exact same sequence of bytes. There are any number of ways you could have created a file with the same bytes in. There's nothing about File.WriteAllText which "marks" the file as text, and there's nothing about FileStream or BinaryWriter which marks the file as binary.
EDIT: From comments:
I'm looking to create a data in binary file until user can not open and read my data by note pad
Well, there are lots of ways of doing that with different levels of security. Ideally, you'd want some sort of encryption - but then the code reading the data would need to be able to decrypt it as well, which means it would need to be able to get a key. That then moves the question to "how do I store a key".
If you only need to verify the data in the file (e.g. check that it matches something from elsewhere) then you could use a cryptographic hash instead.
If you only need to prevent the most casual of snoopers, you could use something which is basically just obfuscation - a very weak form of encryption with no "key" as such. Anyone who dceompiled your code would easily be able to get at the data in that case, but you may not care too much about that.
It all depends on your requirements.
All data is binary. A text file is binary data that happens to be a limited subset that represent valid characters, but it's still binary.
The way text editors typically differentiate a text file from a binary file is they scan a certain portion of the file for zero values, \0. These never exist in text-only files and almost always exist in binary files.
I have a byte[] with some data in it, I would like to write this byte array AS-IS to the log file using log4.net. The problems that i am facing is that
There are no overload for byte[] in TextWriter, so even implementing an IObjectRenderer is of no use.
I dont have access to the underlying Stream object of Log4.net
Also tried converting byte[] into char[] still when i write it, it adds an extra byte.
Is this even possible with Log4.net.
Thanx in Advance.
Log files are usually plain text files. It's probably best to log your byte array represented as string.
Have a look at BitConverter.ToString or Convert.ToBase64String.
Nope. Have you thought about writing it out as a hex string (see this post)?
I also think that logging any larger data is kind of useless, however, i guess this is what you are looking for - this converts your bytes to string.
System.Text.Encoding.ASCII.GetString(byteArray)
I believe you can figure out how to use that for logging.
Pz, the TaskConnect developer
If you are logging into DB then use Binary type with maximum size
Today i'm cutting video at work (yea me!), and I came across a strange video format, an MOD file format with an companion MOI file.
I found this article online from the wiki, and I wanted to write a file format handler, but I'm not sure how to begin.
I want to write a file format handler to read the information files, has anyone ever done this and how would I begin?
Edit:
Thanks for all the suggestions, I'm going to attempt this tonight, and I'll let you know. The MOI files are not very large, maybe 5KB in size at most (I don't have them in front of me).
You're in luck in that the MOI format at least spells out the file definition. All you need to do is read in the file and interpret the results based on the file definition.
Following the definition, you should be able to create a class that could read and interpret a file which returns all of the file format definitions as properties in their respective types.
Reading the file requires opening the file and generally reading it on a byte-by-byte progression, such as:
using(FileStream fs = File.OpenRead(path-to-your-file)) {
while(true) {
int b = fs.ReadByte();
if(b == -1) {
break;
}
//Interpret byte or bytes here....
}
}
Per the wiki article's referenced PDF, it looks like someone already reverse engineered the format. From the PDF, here's the first entry in the format:
Hex-Address: 0x00
Data Type: 2 Byte ASCII
Value (Hex): "V6"
Meaning: Version
So, a simplistic implementation could pull the first 2 bytes of data from the file stream and convert to ASCII, which would provide a property value for the Version.
Next entry in the format definition:
Hex-Address: 0x02
Data Type: 4 Byte Unsigned Integer
Value (Hex):
Meaning: Total size of MOI-file
Interpreting the next 4 bytes and converting to an unsigned int would provide a property value for the MOI file size.
Hope this helps.
If the files are very large and just need to be streamed in, I would create a new reader object that uses an unmanagedmemorystream to read the information in.
I've done a lot of different file format processing like this. More recently, I've taken to making a lot of my readers more functional where reading tends to use 'yield return' to return read only objects from the file.
However, it all depends on what you want to do. If you are trying to create a general purpose format for use in other applications or create an API, you probably want to conform to an existing standard. If however you just want to get data into your own application, you are free to do it however you want. You could use a binaryreader on the stream and construct the information you need within your app, or get the reader to return objects representing the contents of the file.
The one thing I would recommend. Make sure it implements IDisposable and you wrap it in a using!