Re: [keycloak-user] Token Exchange AWS Cognito & Keycloak

Hi Pedro, i'll try to reply to your questions: - We've configured Cognito as an identity provider in Keycloak, importing the configuration via the OIDC discovery-configuration endpoint. At this point we needed to introduce the clientID & secret, so we've created a new confidential client inside AWS Cognito and used its id &secret in the Keycloak's Identity provider config - We've set the permission & policy about token exchange feature to our Keycloak client - The SRP flow leverages the SRP authentication protocol (so basically, no password is sent to the server). The result of this flow is a couple of JWT tokens (access and id token), but the access token doesn't respect the OIDC rules (it doesn't contain the openid scope). This last point is what make the token exchange process impossible (this because, during the process, Cognito replies that "the token doesn't contain the openid scope"). About that i want to highlight the fact that these problems are entirely Cognito related: if we use a standard OAuth2 Flow (like Authorization code grant or implicit) the process works as expected.

- Since the SRP flow enables us to use a self-hosted login page which doesn't send the password directly to the server, we've tried to find other solution. So we've tried to provide to the token exchange endpoint the id token, changing some parameters of the HTTP call. And at this point something unexpected for us happened: the token exchange process works also providing the id token. Here's the reason of my first flow of questions: is this behaviour expected? Is the "exchange with id token" approach a feasible and good one? Or is completely a bad approach? - Since using this flow (SRP) force us to provide the id token to our backend side, here comes the other flow of questions :). From an OIDC point of view, can be a right approach accessing a backend resource from a single page application, using an id token? I've always read that if you want to access to a backend resource, from a client application, is better to use the access token, because the id token contains a lot of user informations and must be used only by the client application.

- Here's the curl of the token exchange process with the access token (i'm omitting some infos): curl -X POST \ -d "client_id=test" \ -d "client_secret=<client_secret>" \ --data-urlencode "grant_type=urn:ietf:params:oauth:grant-type:token-exchange" \ -d "subject_issuer=<alias_of_the_identity_provider_in_keycloak>" \ -d "subject_token=<access_token>" \ --data-urlencode "subject_token_type=urn:ietf:params:oauth:token-type:access_token" \ -d "audience=test" \ http://localhost:8080/auth/realms/ <realm_name>/protocol/openid-connect/token - Here's the curl of the token exchange process with the id token (i'm omitting some infos): curl -X POST \ -d "client_id=test" \ -d "client_secret=<client_secret>" \ --data-urlencode "grant_type=urn:ietf:params:oauth:grant-type:token-exchange" \ -d "subject_issuer=<alias_of_the_identity_provider_in_keycloak>" \ -d "subject_token=<id_token>" \ --data-urlencode "subject_token_type=urn:ietf:params:oauth:token-type:id_token" \ -d "audience=test" \ http://localhost:8080/auth/realms/ <realm_name>/protocol/openid-connect/token Let me know if you need more infos. Thank you again, Matteo Restelli On Wed, Apr 10, 2019 at 3:40 PM Pedro Igor Silva <psilva(a)redhat.com&gt; wrote: > Hi, > > So you are doing external to internal exchange. It is not clear to me how > you configured AWS Cognito as an identity provider and what/how the SRP > flow works. Could you provide more details, please? Is the token issued by > Cognito a JWT ? > > In addition to that, how your token exchange request looks like when > using both id_token and access_token as a subject_token ? > > On Wed, Apr 10, 2019 at 9:56 AM Matteo Restelli <mrestelli(a)cuebiq.com&gt; > wrote: > >> Any news on that? >> >> Thank you! >> Matteo >> >> ============================= >> >> >> Hi all, >> We're using AWS Cognito as our Identity provider for our platform. We're >> trying to use an internal instance of Keycloak, in order to check the >> possibility to use KC for authorization purposes (this because Keycloak >> has >> a wonderful and powerful authorization system that fulfill our needs, and >> for that i want to say you "Thank you very much" :) ). For this reason we >> want to use the token exchange feature of Keycloak. >> More specifically we want to follow this flow: >> >> - User authenticates on AWS Cognito via SRP auth flow (which basically is >> not a standard OIDC/OAuth2 authentication flow) >> - User sends the access token to contact the backend service and, in the >> middle, this token is translated to an internal one, minted by Keycloak >> >> If we provide the AWS Cognito access token to the token exchange >> endpoint, >> with the subject_token_type parameter set to >> "urn:ietf:params:oauth:token-type:access_token", an error is returned >> stating that the access token doesn't contain the "openid" scope. Despite >> this we've tried another way, providing the id token to the token >> exchange >> endpoint with the subject_token_parameter set to >> "urn:ietf:params:oauth:token-type:id_token", and we discovered that this >> alternative way works. So, my questions are: >> >> - Is the "exchange with id token" approach a feasible and good one? Or is >> completely a bad approach? >> - From an OIDC point of view, can be a right approach accessing a backend >> resource from a single page application, using an id token? I've always >> read that if you want to access to a backend resource, from a client >> application, is better to use the access token, because the id token >> contains a lot of user informations and must be used only by the client >> application >> >> Thank you very much, >> Matteo >> >> >> PS: As a side note, i want to clarify that if we follow an authorization >> code grant flow, or an implicit flow, during the authentication against >> AWS >> Cognito, the access token exchange works as expected. So this means that >> the problem is related to the shape of the token released by Cognito. >> >> -- >> >> Like <https://www.facebook.com/cuebiq/> I Follow >> <https://twitter.com/Cuebiq>I Connect >> <https://www.linkedin.com/company/cuebiq> >> >> >> This email is reserved >> exclusively for sending and receiving messages inherent working >> activities, >> and is not intended nor authorized for personal use. 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