Validate AWS Cognito Token with Swift - swift

Question

I have nearly completed the process for a developer authenticated sign in using AWS. I cannot seem to authenticate the back-end token that I receive and cannot seem to find any current implementations that are performing developer authentication via a third-party back-end. The error that I get is listed below.
As of right now my code looks like this:
Class containing Custom identity provider:
import Foundation
import AWSCognitoIdentityProvider
class CustomIdentityProvider: NSObject, AWSIdentityProviderManager {
var tokens: [NSString: NSString]?
init(tokens: [NSString: NSString]) {
self.tokens = tokens
}
#objc func logins() -> AWSTask<NSDictionary> {
return AWSTask(result: tokens! as NSDictionary)
}
}
AWS-APIManager.swift {snippet}
/* obtained cognito token from my back-end via getOpenIdTokenForDeveloperIdentity*/
/* From here I my app receives an IdentityId and Token */
let client_cognito_id = String(describing: valid_response)
let session_token = json.dictionaryValue["Token"]!
let login_with_amazon = NSString(string: "cognito-identity.amazonaws.com")
let token = NSString(string: String(describing: session_token))
let customProviderManager = CustomIdentityProvider(tokens: [login_with_amazon: token])
let credentialsProvider = AWSCognitoCredentialsProvider(
regionType: self.AWS_REGION,
identityPoolId: "us-east-1:XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
identityProviderManager: customProviderManager
)
credentialsProvider.setIdentityProviderManagerOnce(customProviderManager)
credentialsProvider.getIdentityId().continue ({ (task: AWSTask!) -> AnyObject! in
if (task.error != nil) {
print("Error!!!: " + (task.error?.localizedDescription)!)
} else {
// the task result will contain the identity id
let cognitoId = task.result
print(cognitoId)
print("SUCCESS!!!")
}
return nil
})
}
For some odd reason odd reason I can cannot authenticate the token that I have received. I get an error "Invalid login token. Can't pass in a Cognito token.". I've tried to follow the documentation and piece together working code that I have found literally hundreds of sources and cannot seem to be able to move past this part of the authentication process. Any help would be greatly appreciated. Thanks!

Answer 1

I believe the issue here is that although you are supplying the token, you are not setting the identity id that you are getting from your backend. As such, it is calling GetId with a Cognito OpenIdConnectToken, which is not supported.
The simplest client implementation of Developer Authenticated Identities is to extend AWSCognitoCredentialsProviderHelper
Apologies for providing this in Objective C instead of Swift. In your implementation just override the token method.
- (AWSTask<NSString *> *)token {
//get the identity id and token from your server
//You can use AWSTaskCompletionSource if you don't have it and need to get it asynchronously.
//Once you have this information, simply set the identity id and return the token
self.identityId = identityId;
return [AWSTask taskWithResult:token];
}