FileSigCheck 2.0.0

.NET Standard 2.0 This package targets .NET Standard 2.0. The package is compatible with this framework or higher.
There is a newer version of this package available.
See the version list below for details. 
dotnet add package FileSigCheck --version 2.0.0
                    


                    

                
NuGet\Install-Package FileSigCheck -Version 2.0.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="FileSigCheck" Version="2.0.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="FileSigCheck" Version="2.0.0" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="FileSigCheck" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add FileSigCheck --version 2.0.0
                    


                    

                
#r "nuget: FileSigCheck, 2.0.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#:package FileSigCheck@2.0.0
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=FileSigCheck&version=2.0.0
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=FileSigCheck&version=2.0.0
                    


                            Install as a Cake Tool

File Signature Checker

This .NET Standard 2.0 library contains code for checking file signatures in their byte marks.

The file signatures were taken fromt his helpful resource: https://filesignatures.net/ (Thanks to them!)

Supported Extensions

It currently contains file signatures for the following extensions:

  • .png
  • .jpg
  • .jpeg
  • .gif
  • .doc
  • .docx
  • .ppt
  • .pptx
  • .xls
  • .xlsx
  • .pdf
  • .mp3
  • .wav
  • .ogg
  • .mpg
  • .m4a
  • .xml

I will add more signatures if they are requested, or if I desire them.

Base 64 Images

There is a method for checking base 64 strings to see whether they are images.

Use as FileSigCheck.IsValidBase64Image(base64string).

Currently, It will strip the metadata from the start of the string, ignoring the "image/*" MIME declarations.

Usage

A typical scenario in which I have implented this is with a file upload in .NET Core API:

static readonly string[] fileExtensions = { ".pdf", ".jpg", ".jpeg", ".png" };

public async Task<IActionResult> UploadImage([FromForm]IFormFile file)
{
    var ext = Path.GetExtension(file.FileName);

    /* Check the file extension in permissible file types */
    if(!fileExtensions.Contains(ext))
    {
        return StatusCode(StatusCodes.Status415UnsupportedMediaType);
    }
    /* Get the file data */
    using (var rs = file.OpenReadStream())
    {
        /* perform check  */
        if (!FileSecurity.IsValidFileSignature(file.FileName, rs, fileExtensions))
        {
            ModelState.AddModelError("File", $"Is not recognised as a {Path.GetExtension(file.FileName)} file.");
            return BadRequest(ModelState);
        }

        /* Then do what you would normally do with that file... */
    }

    return Ok();
}
Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 was computed.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

  • .NETStandard 2.0

    • No dependencies.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last Updated
2.1.0 200 11/25/2025
2.0.1 207 5/20/2025
2.0.0 191 5/20/2025