Unable to re-authenticate (not refresh) using the same device key

[alfarok]

Describe the bug

I am attempting to use the aws-sdk-net-extensions-cognito library for Cognito authentication with device tracking enabled. The cloud formation properties on the User Pool for this configuration are:

DeviceConfiguration:
    ChallengeRequiredOnNewDevice: false
    DeviceOnlyRememberedOnUserPrompt: false

I can successfully complete the following steps:

• User logins in the for the first time using StartWithSrpAuthAsync (generate a new device key)
• Use the NewDeviceMetadata to create a DeviceVerifier which includes PasswordVerifier and Salt
• Use this to ConfirmDeviceAsync which shows the new device for the user in the Cognito AWS Console dashboard
• As long as the device key is set on the user I can invoke StartWithRefreshTokenAuthAsync to successfully get refresh tokens

My issue at this point is that signing out and attempting to sign back in fails using the device key from the previous session. I know I need to generate a new token but I shouldn't have to regenerate the device key on the same device. Currently, when I tried to login using the device key from the previous session I get the following error:

"Incorrect username or password."

Here is my code for attempting to login using a local device key from the previous session:

user.Device = new CognitoDevice(
    new DeviceType { DeviceKey = deviceKey },
    user
);

var deviceVerifier = user.GenerateDeviceVerifier(DeviceInfo.DeviceGroupKey, password, DeviceInfo.DeviceKey);

authRequest = new InitiateSrpAuthRequest()
{
    Password = password,
    DeviceGroupKey = deviceGroupKey,
    DevicePass = deviceVerifier.PasswordVerifier,
    DeviceVerifier = deviceVerifier.Salt
};

// Fails with 400 error mentioned above
var authResponse = await user.StartWithSrpAuthAsync(authRequest);

I have a feeling it's related to the creation of new InitiateSrpAuthRequest() and the values I am providing. I was unable to find documentation around these parameter values. I was assuming DevicePass is the PasswordVerifier created by GenerateDeviceVerifier and DeviceVerifier is the Salt from GenerateDeviceVerifier but the key names are confusing?

TLDR: What values are expected for DevicePass and DeviceVerifier or am I doing something else incorrectly?

Expected Behavior

I can re-authenticate a user (not refresh) but use the same device key which will not create a new device for that user as long as they are on the same machine.

Current Behavior

• Initial token/device key creation works
• Token refresh works when device key is provided
• Logging out and logging back in fails due "Incorrect username or password."
  • The only difference with the initial auth is the parameters we pass to InitiateSrpAuthRequest()
  • The initial login we only provide the Password
  • Reoccurring logins where a local device key is found in the cache we provide Password, DeviceGroupKey, DevicePass and DeviceVerifier which fails

AWS .NET SDK and/or Package version used

Amazon.Extensions.CognitoAuthentication 2.5.2 (latest)

Targeted .NET Platform

.NET Framework 4.8 & .NET 6.0

Operating System and version

Windows 10/11

[alfarok]

The issue follows a very similar flow outlined in this other old issue https://github.com/aws/aws-sdk-net-extensions-cognito/issues/44 but I am getting a different error at the final step.

Another user on the same thread commented with the SAME ERROR message but his remedy did not seem to help me. He is questioning the signature on GenerateDeviceVerifier(). I have tried username and deviceKey.

[alfarok]

Hi @bhoradc, were you able to reproduce the issue or do you need any additional information? Thanks!

[alfarok]

Hey @96malhar @ashishdhingra, do you know if this repo is being actively maintained or if I should be using a different AWS API for this?

[bhoradc]

Hi @alfarok,

Apologies for some silence here. I haven't got a chance to work on this one yet. I plan to work on reproducing it during this week. And will get back to you with further update or if any information is needed. Thank you.

-->update - I have started working on the repro code for this one, hopefully will complete and have some update soon.

Regards, Chaitanya

[bhoradc]

Hello @alfarok,

Can you check if setting DevicePass = password works in your case?

authRequest = new InitiateSrpAuthRequest()
{
    Password = password,
    DeviceGroupKey = deviceGroupKey,
    DevicePass = password,
    DeviceVerifier = deviceVerifier.Salt
};

Regards, Chaitanya

[alfarok]

Thank you @bhoradc, I am able to re-authenticate now without creating a new device entry. I swear I thought I tried that combo but also refactored my logic from my original attempts so could have been a combination of things. Really appreciate your follow-up and assistance.

For anyone else that comes across this ->

A login attempt where no device key is present must use something similar to this:

// Initialize first login
InitiateSrpAuthRequest authRequest = new InitiateSrpAuthRequest() { Password = password};
// Login
AuthFlowResponse authResponse = await User.StartWithSrpAuthAsync(authRequest).ConfigureAwait(true);
// Extract device metadata
var md = authResponse.AuthenticationResult.NewDeviceMetadata;
// Generate a verifier
var deviceVerifier = User.GenerateDeviceVerifier(md.DeviceGroupKey, password, md.DeviceKey);
// Confirm device
 var confirmDeviceResponse = await User.ConfirmDeviceAsync(AccessToken, md.DeviceKey, DeviceName, DeviceVerifier.PasswordVerifier, DeviceVerifier.Salt);

Attempts where an existing device key is present should use something like this:

// Generate a verifier with cached device data
var deviceVerifier = User.GenerateDeviceVerifier(deviceGroup, password, deviceKey);
// Initialize subsequent logins while cache is present
InitiateSrpAuthRequest authRequest = new InitiateSrpAuthRequest()
{
    Password = password,
    DeviceGroupKey = deviceGroup,
    DevicePass = password,
    DeviceVerifier = deviceVerifier.Salt
};
// Login
AuthFlowResponse authResponse = await User.StartWithSrpAuthAsync(authRequest).ConfigureAwait(true);

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