#### [Abblix\.Oidc\.Server](https://www.abblix.com/en/docs/api/abblix-oidc-server 'index')
### [Abblix\.Oidc\.Server\.Endpoints\.BackChannelAuthentication\.Validation](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation 'Abblix\.Oidc\.Server\.Endpoints\.BackChannelAuthentication\.Validation')

## RequestedSubjectValidator Class

Refuses a `claims` request whose `sub` qualifier is not a string\.

```csharp
public class RequestedSubjectValidator : Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.IBackChannelAuthenticationContextValidator
```

Inheritance [System\.Object](https://learn.microsoft.com/en-us/dotnet/api/system.object 'System\.Object') → RequestedSubjectValidator

Implements [IBackChannelAuthenticationContextValidator](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.IBackChannelAuthenticationContextValidator 'Abblix\.Oidc\.Server\.Endpoints\.BackChannelAuthentication\.Validation\.IBackChannelAuthenticationContextValidator')

### Remarks
This endpoint accepts the same `claims` parameter as the authorization endpoint and honours a
`sub` named in it the same way \- OpenID Connect Core 1\.0 Section 3\.1\.2\.2 makes that and
`id_token_hint` two ways of stating one requirement\. What differs is only where the comparison
happens, since the end user answers on a device long afterwards\.

A malformed qualifier is refused here rather than left to the comparison, which would treat it as naming
nobody and answer as though the end user were simply unreachable. Section 5.5.1 requires the qualifier to
be "a valid value for the Claim being requested" and Section 2 makes `sub` a string, so a number or
an object is a request nobody could satisfy, and saying that outright is the difference between a client
fixing its request and a client retrying it.
### Methods

## RequestedSubjectValidator\.ValidateAsync\(BackChannelAuthenticationValidationContext\) Method {#Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.RequestedSubjectValidator.ValidateAsync(Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.BackChannelAuthenticationValidationContext)}

Asynchronously validates the backchannel authentication request context\.
This method checks the context of the request, including client information and requested parameters,
to ensure compliance with security and protocol requirements\.

```csharp
public System.Threading.Tasks.Task<Abblix.Oidc.Server.Common.OidcError?> ValidateAsync(Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.BackChannelAuthenticationValidationContext context);
```
#### Parameters

###### `context` [BackChannelAuthenticationValidationContext](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.BackChannelAuthenticationValidationContext 'Abblix\.Oidc\.Server\.Endpoints\.BackChannelAuthentication\.Validation\.BackChannelAuthenticationValidationContext') {#Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.RequestedSubjectValidator.ValidateAsync(Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.BackChannelAuthenticationValidationContext).context}

The context of the backchannel authentication request that needs to be validated\.

Implements [ValidateAsync\(BackChannelAuthenticationValidationContext\)](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.IBackChannelAuthenticationContextValidator#Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.IBackChannelAuthenticationContextValidator.ValidateAsync(Abblix.Oidc.Server.Endpoints.BackChannelAuthentication.Validation.BackChannelAuthenticationValidationContext) 'Abblix\.Oidc\.Server\.Endpoints\.BackChannelAuthentication\.Validation\.IBackChannelAuthenticationContextValidator\.ValidateAsync\(Abblix\.Oidc\.Server\.Endpoints\.BackChannelAuthentication\.Validation\.BackChannelAuthenticationValidationContext\)')

#### Returns
[System\.Threading\.Tasks\.Task&lt;](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task-1 'System\.Threading\.Tasks\.Task\`1')[OidcError](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Common.OidcError 'Abblix\.Oidc\.Server\.Common\.OidcError')[&gt;](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task-1 'System\.Threading\.Tasks\.Task\`1')  
A task that represents the asynchronous validation operation\. The task result contains
a [OidcError](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Common.OidcError 'Abblix\.Oidc\.Server\.Common\.OidcError') if validation fails, or null if the context is valid\.