GoogleAuthenticator 3.2.0

There is a newer prerelease version of this package available.
See the version list below for details.
dotnet add package GoogleAuthenticator --version 3.2.0                
NuGet\Install-Package GoogleAuthenticator -Version 3.2.0                
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="GoogleAuthenticator" Version="3.2.0" />                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add GoogleAuthenticator --version 3.2.0                
#r "nuget: GoogleAuthenticator, 3.2.0"                
#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.
// Install GoogleAuthenticator as a Cake Addin
#addin nuget:?package=GoogleAuthenticator&version=3.2.0

// Install GoogleAuthenticator as a Cake Tool
#tool nuget:?package=GoogleAuthenticator&version=3.2.0                


Simple, easy to use server-side two-factor authentication library for .NET that works with Google Authenticator

Build Status NuGet Status

Install-Package GoogleAuthenticator


Additional examples at Google.Authenticator.WinTest and Google.Authenticator.WebSample

key should be stored by your application for future authentication and shouldn't be regenerated for each request. The process of storing the private key is outside the scope of this library and is the responsibility of the application.

using Google.Authenticator;

string key;

TwoFactorAuthenticator tfa = new TwoFactorAuthenticator();
SetupCode setupInfo = tfa.GenerateSetupCode("Test Two Factor", "", key, false, 3);

string qrCodeImageUrl = setupInfo.QrCodeSetupImageUrl;
string manualEntrySetupCode = setupInfo.ManualEntryKey;

imgQrCode.ImageUrl = qrCodeImageUrl;
lblManualSetupCode.Text = manualEntrySetupCode;

// verify
TwoFactorAuthenticator tfa = new TwoFactorAuthenticator();
bool result = tfa.ValidateTwoFactorPIN(key, txtCode.Text)

Update history


Added support for HMACSHA256 and HMACSHA512 as per the RFC spec. In testing it was found that several popular apps (such as Authy and Microsoft Authenticator) may not have support for these algorithms so care should be taken by the developer to ensure compatible apps are used.


Fixed an edge case where specifying an interval of 30 seconds to the Validate function would be treated as if you had passed in 0.


  • Removed .NET 5 and added .NET 7 to test frameworks
  • Updated dependencies for test runs
  • Support ValidateTwoFactorPIN with iterationOffset as parameter


  • Removed support for legacy .Net Framework. Lowest supported versions are now netstandard2.0 and .Net 4.6.2.
  • All use of System.Drawing has been removed. In 2.5, only Net 6.0 avoided System.Drawing.
  • Linux installations no longer need to ensure libgdiplus is installed as it is no longer used.
  • Changed from using EscapeUriString to EscapeDataString to encode the "account title" as the former is obsolete in .Net 6. This changes the value in the generated data string from to We have tested this with Google Authenticator, Lastpass Authenticator and Microsoft Authenticator. All three of them handle it correctly and all three recognise that it is still the same account so this should be safe in most cases.


Now runs on .Net 6.0.
Technically the QR Coder library we rely on still does not fully support .Net 6.0 so it is possible there will be other niggling issues, but for now all tests pass for .Net 6.0 on both Windows and Linux.

Common Pitfalls

  • Old documentation indicated specifying width and height for the QR code, but changes in QR generation now uses pixels per module (QR "pixel") so using a value too high will result in a huge image that can overrun memory allocations
  • Don't use the secret key and ManualEntryKey interchangeably. ManualEntryKey is used to enter into the authenticator app when scanning a QR code is impossible and is derived from the secret key (discussion example)
  • With versions prior to 3.0 only, on linux, you need to ensure libgdiplus is installed if you want to generate QR Codes. See
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. 
.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 is compatible.  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.
  • .NETFramework 4.6.2

  • .NETStandard 2.0

NuGet packages (38)

Showing the top 5 NuGet packages that depend on GoogleAuthenticator:

Package Downloads

Geeks Core Library


Content Repository layer for the sensenet platform.


Integration with Google MFA


Package Description


Custom extension for Google Authenticator

GitHub repositories (7)

Showing the top 5 popular GitHub repositories that depend on GoogleAuthenticator:

Repository Stars
ASP.NET Core eCommerce software. nopCommerce is a free and open-source shopping cart.
Free open source office suite with business productivity tools: document and project management, CRM, mail aggregator.
Open source, headless, multi-tenant eCommerce platform built with .NET Core, MongoDB, AWS DocumentDB, Azure CosmosDB, Vue.js.
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Version Downloads Last updated
3.3.0-beta1 25,486 3/13/2024
3.2.0 281,618 1/12/2024
3.1.1 214,602 10/4/2023
3.1.1-beta1 3,225 5/30/2023
3.1.0 377,123 5/3/2023
3.0.0 1,194,694 6/1/2022
3.0.0-beta2 789 5/26/2022
3.0.0-beta1 1,221 5/6/2022
2.5.0 185,821 4/13/2022
2.4.0 201,203 12/28/2021
2.3.0 117,085 11/30/2021
2.2.0 391,495 7/13/2021
2.1.1 509,698 12/3/2020
2.0.1 436,552 1/10/2020
2.0.0 11,497 1/2/2020
1.2.1 1,325,475 12/7/2016
1.2.0 106,986 9/23/2015
1.1.0 8,866 1/7/2015
1.0.0 3,245 9/8/2014

Added support for HMACSHA256 and HMACSHA512 as per the RFC spec. Care should be taken by the developer to ensure compatible apps are used.