How to validate getOpenIdTokenForDeveloperIdentity cognito token

Question

I am building an authentication system using aws lambdas, dynamodb and cognito.

Am stuck at comparing the token provided from the getOpenIdTokenForDeveloperIdentity(); call with one from the server for the specific identity.

Am getting the token and identity with:

function getToken(email, fn) {
    var param = {
        IdentityPoolId: cognitoIdentityPoolId,
        Logins: {} // To have provider name in a variable
    };
    param.Logins[cognitoDeveloperProvidedName] = email;
    cognitoidentity.getOpenIdTokenForDeveloperIdentity(param,
        function(err, data) {
            if (err) return fn(err); // an error occurred
            else fn(null, data.IdentityId, data.Token); // successful response
        });
}

Then as far as I understand it I can get the already generated token from cognito (not create a new one) like this:

function checkToken(IdentityId, email, fn){
    var param = {
        IdentityPoolId: cognitoIdentityPoolId,
        IdentityId: IdentityId,
        Logins: {}
    };
    param.Logins[cognitoDeveloperProvidedName] = email;
    cognitoidentity.getCredentialsForIdentity(param, 
        function(err, data) {
            if (err) return fn(err);
            else fn(null, data);
        });
}

But I can't seem to get it to work

Any ideas?

Answer 1

Figured it out, the checkToken function needs to look like this:

function checkToken(providedIdentity, token, fn){
    var param = {
        IdentityId: providedIdentity,
        Logins: {}
    };
    param.Logins['cognito-identity.amazonaws.com'] = token;
    cognitoidentity.getCredentialsForIdentity(param, 
        function(err, data) {
            if (err) return fn(err);
            else fn(null, data);
        });
}

I needed to set cognito-identity.amazonaws.com as the login provider