Is AWS Amplify the only way to make SDK calls to Cognito? - amazon-web-services

I'm trying to integrate Cognito Authorizers into an existing application that is using API Gateway to authorize requests.
The documentation insists on using AWS Amplify to make these calls, but I'm not sure that this fits in well with the existing architecture since Amplify seems to have its own way of making API requests, and I'm worried that it would mandate having to change all of the existing API requests...
So my question is if there are more readily integratable solutions to this problem, or if my concerns are unfounded.

There are several SDK's that can be used with Cognito.
You can use the AWS js SDK to make low level API calls but you will lose the benefits that the Cognito Client Side SDKS provide like session management, caching of tokens and SRP calculations.
https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CognitoIdentityServiceProvider.html
You can also use the Cognito Identity SDK which Amplify uses under the hood:
https://www.npmjs.com/package/amazon-cognito-identity-js
The Auth SDK if you are going to be integrating with the OAuth endpoints, which is now deprecated but can still be used or referenced, Amplify also uses or has similar functionality.
https://github.com/amazon-archives/amazon-cognito-auth-js
And then finally Amplify which is the go to, feature rich client side SDK which for the majority of usecases should be the SDK of choice in my opinion.

Related

How to give access to API behing AWS Api Gateway from our SDK

we use Aws Api Gateway to protect our apis.
We want to create an sdk for developers. The idea is to have In app purchase in their apps and call our apis in order to start payment.
We are trying to have a way to connect machine from machine. The first machine will be an sdk integrated in Android games and the second will be our back end protected by the api gateway.
The sdk should have a the authorization to consume the api.
Today we don't know how to do it, even after discussing with many architects.
The sdk is not going to have user and password, because it is not a user, so no way to generate the classic access token.
How could we achieve this use case ?
Thanks
The sdk should have a the authorization to consume the api. Today we don't know how to do it, even after discussing with many architects.
There are three possible ways to have a protected API Gateway. AWS Cognito and AWS Lambda. The third option, API Keys, is a little bit different than the previous two.
With Cognito, you create user pools and API Gateway automatically handles authorization when a request is received.
With Lambda, you create your own custom authorization logic.
I generally prefer the Lambda approach due to the ease of use but it depends on the use-case.
With the API Key option, you create API Keys for specific routes and API Gateway checks them through the request headers. I think any use-case that requires this can be handled with the Lambda option as well.
What you are describing doesn't sound difficult to achieve.
You will generate an API key and you will give them to the developers that will use your API.
In your SDK, you can accept the API key as an initialization parameter and provide it in the requests to API Gateway.

Is there a REST API Reference available for AWS?

As far as I understand, there are only three ways to access AWS resources:
Management Console (browser)
AWS CLI
AWS SDK (in various programming languages)
However, why did not AWS provide REST APIs and their reference document so that we can interact with AWS resources directly using a REST client like Postman?
I think they are using REST APIs behind the scenes (All the above three interactions actively use REST API I guess).
Thanks in advance.
There is REST API documentation available as well. Its just that AWS officially encourages the use of more abstract methods such as using CLI and SDK since its easier to use as well as they are maintained by AWS.
Also using the sdk or cli is encouraged because they are perfectly interfaced with the aws rest api with extensive testing and covering all cases. And you don't need to focus on stuff like what headers you need to attach or what should be the request body format. Users can focus on writing their own business logic.
The only source I could find for documentation of rest api are the official docs which I have linked below. Since the direct use of rest api is not preferred hence no commonly available tutorials. I don't think there is anything extra which can be accomplished using the rest api which the cli or sdk doesn't already offer.
A more practical example would be aws s3 cli. It has a lot of underlying implementation which speeds up the process of uploading and downloading, like establishing 10 network connections in parallel to utilize the complete network bandwidth etc. This you would have to implement yourself if you are directly using the api.
Some Examples:
S3 REST API
EC2 REST API
Similarly there is API documentation available for every service.

Custom authorizer vs Cognito - authentication for amazon api gateway - Web application

I have been making a web app. (Angular 2 on S3 and APIs in lambda through API gateway). For authentication I played both with cognito and custom authorizer (I configured my authentication to work with Google and Facebook bith via a custom authorizer and cognito). In case of custom authorizer I am passing a token via authroization header and my custom authorizer validates it.
I am looking for advice on which should I go forward with and what are their pros and cons. Ones that I could think of are:
AWS cognito:
Pros
AWS SDK handles everything for you and you cannot make much mistake in your authentication process.
Fine grained access control for AWS resources via IAM.
An extra lambda function in front of every API is not required for authentication.
Cons
Need to use AWS SDK specifically on client side. Programmers have to add this into their toolchain and make use if it during development. Adds extra complexity.
Fine grained access control for resources is not really required since the only access that is required is for API gateway.
Custom authorizer
Pros
You can have your authentication mechanism the way you want it. Ultimate control over authentication and authorization.
You can have the UI call the APIs with a standard token (JWT) and the flow for developers remains same. No extra consideration of AWS SDK.
Cons
Authentication requires a lot of thinking and effort to build.
Chances of missing some crucial aspects are always there.
Its like reinventing the wheel. Why do it when Amazon has already done it for you.
All that being said, I am leaning towards custom authorizer for now. Need advice here on the topic.
PS: I know there cannot be a definite answer to the question I have posted but it would be of great help to people trying to decide on authentication for their applications.
okay, authentication and security is indeed hard and there are a lot of issues that have been thought about and taken care by AWS security team that you may not think of and implement and make your application insecure. I implemented my custom authorizer to expect an authorization token (passed through authorization header) that was a base64 encoded value which would repeat across all the requests in a session. It turns out that due to weaknesses in RC4 and diffie hellman this makes the TLS susceptible to attack. If we simply use cognito using IAM then AWS sigv4 request signing protects you from these weaknesses. Watch https://www.youtube.com/watch?v=zmMpgbIhCpw for more details.
Another benefit of using cognito/IAM is that it protects you against CSRF replay attack. Request signing involves using timestamp. IAM will deny any requests that are signed more than ~5 minutes ago.
In short avoid using custom authorizer if you can and use IAM with cognito. You will thank yourself.
This is a short answer but, why not use both of them?
Use a custom authorizer that is actually implemented to use Cognito Users Pool and Cognito Federated Identities.
When you use Cognito you can make the choice not to use everything.
For example I set up a custom Authorizer and my Lambda is actually using Cognito Users Pool API to authenticate the user. I let Cognito Users Pool to handle all the passwords, tokens, etc..

Using AWS Cognito under the backend API

I wanted to check we can use a custom node.js implementation as wrapper for exposing the API's for identity and user management using aws cognito.
We already have a bunch of API's (on ASP.NET identity) and would not want to change anything in the downstream systems. We would like keep the API signatures and just move the implementation to node.js server for identity and user management
The current examples on awslabs and the documentation is mainly targeted for using this under a web/mobile applications. Is there any guideline/sample if we can use this as an API wrapper.
Apologies if I'm misinterpreting the question, but are you just trying to use Cognito with node instead of on a web app? Are you asking about Cognito federated identities or Cognito user pools?
If federated identities, yes, that will be fine and you shouldn't have any issues. All of the APIs are available in the node SDK, and the general flow should be identical to any other non mobile flow.
If you're asking about user pools, it's a bit trickier. Authentication uses SRP to validate passwords, and the mobile/web SDKs do this for you. Outside of those, you'd have to implement it yourself, which is no fun at all. You could rip out the code that does it from any one of those SDKs (each are published on Github) to help with that. Alternatively, you could use admin no srp authentication, which carries the risk of sending the username/password over the wire but passes off the authentication to the Cognito server.

AWS API Gateway vs AWS Cognito

I'd like to run some stateless Java services on the Bitnami stack on AWS that will be consumed by apps... and of course to access these I'd need some type of authentication and authorization.
Previously with this type of architecture I've chucked an API gateway in front of them, to which the developer would subscribe. And AWS provides an API gateway, nice.
HOWEVER, while reading up on how to set this up on AWS I came across 'AWS Cognito' which is supposedly designed specifically for this same purpose.
So my question is are these two solutions comparable - are they doing the same thing?
And if-so, then what are the pros and cons of each, when would choose one over the other?
Basically because you are targeting the user level you should use Cognito; as it does provide you with authentication, reseting passwords for the user, and of course
signing up workflow. Moreover it provides user information to the admin, as well as two factor authentication, by using the user's mobile phone.
If you want to authorize the application to use an api then you use the API Gateaway.
The Cognito, is designed for user interaction it has an api for Java, JavaScript, iOS, and Android, so you can
implement the interaction with it at any level; as you wish. You also not getting changed if your user base is less than 50k.