(Mono C#) Get Access Token using a Pre-Created JSON Web Token

Demonstrates how to get an access token using a pre-created JSON Web Token (JWT).

For more information, see https://developer.abnamro.com/get-started#headingFive

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// We're going to duplicate this CURL statement:
// curl -X POST https://api-sandbox.abnamro.com/v1/oauth/token \
// -H "Content-Type: application/x-www-form-urlencoded" \
// -H "API-Key: xxxxxx" \
// -d 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer&grant_type=client_credentials&client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ4eHh4eHgiLCJleHAiOiIxNDk5OTQ3NjY4IiwiaXNzIjoibWUiLCJhdWQiOiJodHRwczovL2F1dGgtc2FuZGJveC5hYm5hbXJvLmNvbS9vYXV0aC90b2tlbiJ9.jGwHKG_YjgKpR8NPpaLu6nJ97obeP2vcxg6fOWBKdJ0&scope=tikkie'

// Load our pre-creaed private key PEM file.
// Note: Please share your public key along with your app name and developer email id at api.support@nl.abnamro.com. 
// Token generation will not work unless public key is associated with your app.
Chilkat.PrivateKey privkey = new Chilkat.PrivateKey();

bool success = privkey.LoadPemFile("qa_data/pem/abnAmroPrivateKey.pem");
if (success == false) {
    Debug.WriteLine(privkey.LastErrorText);
    return;
}

// Create the JWT.
Chilkat.Jwt jwt = new Chilkat.Jwt();

// Create the header:
// {
//     "typ": "JWT",
//     "alg": "RS256"
// }
Chilkat.JsonObject jsonHeader = new Chilkat.JsonObject();
jsonHeader.UpdateString("typ","JWT");
jsonHeader.UpdateString("alg","RS256");

// Create the payload:
// {
//     "nbf": 1499947668,
//     "exp": 1499948668,
//     "iss": "me",
//     "sub": "anApiKey",
//     "aud": "https://auth-sandbox.abnamro.com/oauth/token"
// }
Chilkat.JsonObject jsonPayload = new Chilkat.JsonObject();

int curDateTime = jwt.GenNumericDate(0);

// Set the "not process before" timestamp to now.
success = jsonPayload.AddIntAt(-1,"nbf",curDateTime);

// Set the timestamp defining an expiration time (end time) for the token
// to be now + 1 hour (3600 seconds)
success = jsonPayload.AddIntAt(-1,"exp",curDateTime + 3600);

jsonPayload.UpdateString("iss","me");
jsonPayload.UpdateString("sub","anApiKey");
jsonPayload.UpdateString("aud","https://auth-sandbox.abnamro.com/oauth/token");

// Produce the smallest possible JWT:
jwt.AutoCompact = true;

string jwtStr = jwt.CreateJwtPk(jsonHeader.Emit(),jsonPayload.Emit(),privkey);
if (jwt.LastMethodSuccess != true) {
    Debug.WriteLine(jwt.LastErrorText);
    return;
}

Chilkat.Http http = new Chilkat.Http();

Chilkat.HttpRequest req = new Chilkat.HttpRequest();
req.AddParam("client_assertion_type","urn:ietf:params:oauth:client-assertion-type:jwt-bearer");
req.AddParam("grant_type","client_credentials");
req.AddParam("client_assertion",jwtStr);
req.AddParam("scope","tikkie");

Chilkat.HttpResponse resp = http.PostUrlEncoded("https://api-sandbox.abnamro.com/v1/oauth/token",req);
if (http.LastMethodSuccess == false) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

if (resp.StatusCode != 200) {
    Debug.WriteLine(resp.BodyStr);

    return;
}

// Get the JSON result:
// {
//     "access_token": "{your access token}",
//     "expires_in": "{duration of validity in seconds}",
//     "scope": "{scope(s) for which the access token is valid}",
//     "token_type": "{it is always Bearer}"
// }
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.Load(resp.BodyStr);
Debug.WriteLine("access_token: " + json.StringOf("access_token"));
Debug.WriteLine("token_type: " + json.StringOf("token_type"));
Debug.WriteLine("expires_in: " + json.StringOf("expires_in"));
Debug.WriteLine("scope: " + json.StringOf("scope"));