(Objective-C) Decode Microsoft Graph ID Token

Demonstrates how to decode a Microsoft Graph ID token.

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#import <CkoJsonObject.h>
#import <CkoJwt.h>
#import <NSString.h>

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

// In a previous example, we obtained a Microsoft Graph OAuth2 access token.
// This example loads the JSON saved from the previous example and decodes the id_token.

// Our Microsoft Graph OAuth2 token looks like this:

// {
//   "token_type": "Bearer",
//   "scope": "openid profile User.ReadWrite Mail.ReadWrite Mail.Send Files.ReadWrite User.Read Calendars.ReadWrite Group.ReadWrite.All",
//   "expires_in": 3600,
//   "ext_expires_in": 3600,
//   "access_token": "EwCQA8l6...0HhMKYwC",
//   "refresh_token": "MCWulIvzi2yD0S...igEFn51mqcByhZtAJg",
//   "id_token": "eyJ0eXAiOiJKV1...Q7lRDaR-7A",
//   "expires_on": "1562862714"
// }

CkoJsonObject *jsonToken = [[CkoJsonObject alloc] init];
BOOL success = [jsonToken LoadFile: @"qa_data/tokens/microsoftGraph.json"];
if (success == NO) {
    NSLog(@"%@",@"Failed to load the JSON file...");
    return;
}

// Use Chilkat's JWT API to examine the id_token..
CkoJwt *jwt = [[CkoJwt alloc] init];
NSString *idToken = [jsonToken StringOf: @"id_token"];

// Extract the JOSE header..
NSString *jose = [jwt GetHeader: idToken];

CkoJsonObject *jsonHeader = [[CkoJsonObject alloc] init];
[jsonHeader Load: jose];
jsonHeader.EmitCompact = NO;
NSLog(@"%@",[jsonHeader Emit]);

// The JOSE header looks like this:

// {
//   "typ": "JWT",
//   "alg": "RS256",
//   "kid": "1LTMzakihiRla_8z2BEJVXeWMqo"
// }

NSString *claims = [jwt GetPayload: idToken];

CkoJsonObject *jsonClaims = [[CkoJsonObject alloc] init];
[jsonClaims Load: claims];
jsonClaims.EmitCompact = NO;
NSLog(@"%@",[jsonClaims Emit]);

// The claims look like this:

// {
//   "ver": "2.0",
//   "iss": "https://login.microsoftonline.com/9188040d-6c67-4c5b-b112-36a304b66dad/v2.0",
//   "sub": "AAAAAAAAAAAAAAAAAAAAAHJFryd6Gydo-XtTd1nhUNQ",
//   "aud": "18c456bd-db75-43fe-9724-9e5d821c68ff",
//   "exp": 1562945513,
//   "iat": 1562858813,
//   "nbf": 1562858813,
//   "name": "Matt Chilkat",
//   "preferred_username": "matt@example.com",
//   "oid": "00000000-0000-0000-3a33-fceb9b74cc15",
//   "tid": "9188040d-6c67-4c5b-b112-36a304b66dad",
//   "aio": "DfibJqKnWC1c0FS6G ... W6pvTrQuYzyq16ghY$"
// }
// 

// Use this online tool to generate parsing code from sample JSON: 
// Generate Parsing Code from JSON

// Get each of the claims..
NSString *ver = [jsonClaims StringOf: @"ver"];
NSString *iss = [jsonClaims StringOf: @"iss"];
NSString *s_sub = [jsonClaims StringOf: @"sub"];
NSString *aud = [jsonClaims StringOf: @"aud"];
int exp = [[jsonClaims IntOf: @"exp"] intValue];
int iat = [[jsonClaims IntOf: @"iat"] intValue];
int nbf = [[jsonClaims IntOf: @"nbf"] intValue];
NSString *name = [jsonClaims StringOf: @"name"];
NSString *preferred_username = [jsonClaims StringOf: @"preferred_username"];
NSString *oid = [jsonClaims StringOf: @"oid"];
NSString *tid = [jsonClaims StringOf: @"tid"];
NSString *aio = [jsonClaims StringOf: @"aio"];