https://github.com/yortw/yort.otp
A portable .Net class library for creating onetime passwords (based on rfc4226 - https://tools.ietf.org/html/rfc4226 and rfc6238 - https://tools.ietf.org/html/rfc6238)
https://github.com/yortw/yort.otp
2fa one-time otp password
Last synced: 6 months ago
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A portable .Net class library for creating onetime passwords (based on rfc4226 - https://tools.ietf.org/html/rfc4226 and rfc6238 - https://tools.ietf.org/html/rfc6238)
- Host: GitHub
- URL: https://github.com/yortw/yort.otp
- Owner: Yortw
- License: mit
- Created: 2016-05-28T07:30:25.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2019-07-25T09:33:30.000Z (about 6 years ago)
- Last Synced: 2025-04-12T20:47:34.953Z (6 months ago)
- Topics: 2fa, one-time, otp, password
- Language: C#
- Homepage: http://yortw.github.io/Yort.Otp/
- Size: 1.51 MB
- Stars: 18
- Watchers: 4
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- Contributing: CONTRIBUTING.md
- License: LICENSE.md
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README
# Yort.Otp
A portable .Net class library for creating onetime passwords (based on [[rfc4226](https://tools.ietf.org/html/rfc4226)] and [[rfc6238](https://tools.ietf.org/html/rfc6238)]).
These are the sorts of authentication codes used by Google/Microsoft/Facebook/Amazon etc. for second factor authentication.
[](https://github.com/Yortw/Yort.Otp/blob/master/LICENSE.md)
## Supported Platforms
Currently;
* .Net Framework 4.0
* Windows Phone Silverlight (8.1+)
* Xamarin.iOS
* Xamarin.Android
* WinRT (Windows Store Apps 8.1)
* UWP 10+ (Windows 10 Universal Programs)
## Build Status
[](https://ci.appveyor.com/project/Yortw/yort-otp)
## Available on Nuget
```powershell
PM> Install-Package Yort.Otp
```
[](https://www.nuget.org/packages/Yort.Otp/)
## Samples
If you're implementing this on a server you should really read and understand the RFC specifications (linked above). There are sever specific issues around managing out of sync counters or client/server times that need to be understood.
Here are some quick start samples;
```c#
public void Main(string[] args)
{
// Generate a "time based" password from the current time (retrieved via DateTime.UtcNow),
// using the ASCII secret in the sample section of https://tools.ietf.org/html/rfc6238.
// This uses a default interval of 30 seconds (maximum length of time the password is value for).
using (var passwordGenerator = new TimeBasedPasswordGenerator(false, OnetimePasswordSecret.FromAscii("12345678901234567890")))
{
System.Diagnostics.Debug.WriteLine($"Password: {passwordGenerator.GeneratedPassword} valid until {((TimeBasedPasswordGenerator)passwordGenerator).ValidUntilUtc.ToLocalTime()}");
}
}
```
```c#
public void Main(string[] args)
{
// Generate a "counter based" one time password from a counter value of 10,
// using the ASCII secret in the sample section of https://tools.ietf.org/html/rfc6238
// The counter should be incremented on each *successful* login, and stored between sessions. See the RFC spec for details.
using (var passwordGenerator = new CounterBasedPasswordGenerator(false, OnetimePasswordSecret.FromAscii("12345678901234567890")))
{
passwordGenerator.Counter = 10;
System.Diagnostics.Debug.WriteLine("Password: " + passwordGenerator.GeneratedPassword);
}
}
```
If you're going to generate passwords for many different secrets but using an otherwise consistent configuration, factories can make that easier/more concise;
```c#
// Counter based factory sample
//During startup, obtain and keep a reference to a factory
_OtpFactory = OnetimePasswordGeneratorFactory.CreateFactory(true, new Sha512HashAlgorithm(), 8);
//When you want to generate a password...
using (var passwordGenerator = _OtpFactory.CreateNewPasswordGenerator(OnetimePasswordSecret.FromAscii("12345678901234567890"), 10))
{
System.Diagnostics.Debug.WriteLine($"Password: {passwordGenerator.GeneratedPassword}");
}
// Time based factory sample
//During startup, obtain and keep a reference to a factory
_OtpFactory = OnetimePasswordGeneratorFactory.CreateFactory(true, new Sha512HashAlgorithm(), 8, TimeSpan.FromMinutes(1));
//When you want to generate a password...
using (var passwordGenerator = _OtpFactory.CreateNewPasswordGenerator(OnetimePasswordSecret.FromAscii("12345678901234567890")))
{
System.Diagnostics.Debug.WriteLine($"Password: {passwordGenerator.GeneratedPassword} valid until {((TimeBasedPasswordGenerator)passwordGenerator).ValidUntilUtc.ToLocalTime()}");
}
```
This library *doesn't* generate QR codes, but it can generate the OTP uri to be turned into a QR code for configuring authenticator apps;
```c#
var configureAuthenticatorUri = OnetimePasswordGeneratorFactory.GetOtpUrl("account name or identifier", "SHA1", 8, OnetimePasswordSecret.FromAscii("12345678901234567890"), TimeSpan.FromMinutes(1));
```
Likewise, if given an OTP uri it can configure a password generator appropriately. This also returns the secret and account name, so they can be stored if required.
```c#
string label = null;
byte[] secret = null;
var passwordGenerator = OnetimePasswordGeneratorFactory.FromOtpUrl(configureAuthenticatorUri, out label, out secret);
```