Perl
Azure OpenID Connect Step 2 -- Get id_token and Validate

After getting the endpoints by querying the Azure's OIDC well-known discovery document (OpenID Configuration document), we use the authorization_endpoint to get the id_token, and then validate it..
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Perl
use chilkat();

$success = 0;

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

# In our previous example (Azure Fetch OpenID Connect metadata document) we fetched
# the OpenID configuration document which is JSON which contains an entry for authorization_endpoint.

$authorization_endpoint = "https://login.microsoftonline.com/{tenant}/oauth2/v2.0/authorize";

# The OpenID Connect metadata document also contained a jwks_uri entry.  This is the JSON Web Key Set (JWKS),
# which is a set of keys containing the public keys used to verify any JSON Web Token (JWT) (in this case the id_token)
# issued by the authorization server and signed using the RS256 signing algorithm. 
$jwks_uri = "https://login.microsoftonline.com/{tenant}/discovery/v2.0/keys";

# We're going to send the following GET request, but it will be sent through an interactive web browser (not by Chilkat).
# The following code will form the URL that is to be programmatically loaded and sent in a browser.

# GET https://login.microsoftonline.com/{tenant}/oauth2/v2.0/authorize?
# client_id=6731de76-14a6-49ae-97bc-6eba6914391e
# &response_type=id_token
# &redirect_uri=http%3A%2F%2Flocalhost%2Fmyapp%2F
# &response_mode=form_post
# &scope=openid
# &state=12345
# &nonce=678910

# Use this object to set params and then get the URL-encoded query params string 
$req = chilkat::CkHttpRequest->new();
$req->AddParam("client_id","{client_id}");
$req->AddParam("response_type","id_token");
$req->AddParam("redirect_uri","http://localhost:3017/");
$req->AddParam("response_mode","form_post");
$req->AddParam("scope","openid");
$prng = chilkat::CkPrng->new();
$req->AddParam("state",$prng->genRandom(3,"decimal"));
$req->AddParam("nonce",$prng->genRandom(4,"decimal"));

$encodedParams = $req->getUrlEncodedParams();
print $encodedParams . "\r\n";

# Sample URL encoded params:
# client_id=6731de76-14a6-49ae-97bc-6eba6914391e&redirect_uri=http%3A%2F%2Flocalhost%3A3017%2F&response_mode=form_post&scope=openid&state=3572902&nonce=57352474

# This is the URL to be programmatically loaded and sent in an interactive web browser..
$sbUrl = chilkat::CkStringBuilder->new();
$sbUrl->Append($authorization_endpoint);
$sbUrl->Append("?");
$sbUrl->Append($encodedParams);
$url = $sbUrl->getAsString();

# Before we launch the browser with the contents of sbUrl, create a socket to listen for the eventual callback..

$listenSock = chilkat::CkSocket->new();

# This is the connection received from the browser.
$browserSock = chilkat::CkSocket->new();

# Listen at the port indicated by the redirect_uri above.
$backLog = 5;
$success = $listenSock->BindAndListen(3017,$backLog);
if ($success == 0) {
    print $listenSock->lastErrorText() . "\r\n";
    exit;
}

# Wait for the browser's connection in a background thread.
# (We'll send load the URL into the browser following this..)
# Wait a max of 60 seconds before giving up.
$maxWaitMs = 30000;
# task is a Task
$task = $listenSock->AcceptNextAsync($maxWaitMs,$browserSock);
$task->Run();

# -------------------------------------------------------------------
# At this point, your application should load the URL in a browser.
$oauth2 = chilkat::CkOAuth2->new();
$success = $oauth2->LaunchBrowser($url);
if ($success == 0) {
    print $oauth2->lastErrorText() . "\r\n";
    exit;
}

# -------------------------------------------------------------------

# Wait for the listenSock's task to complete.
$success = $task->Wait($maxWaitMs);
if (!$success or ($task->get_StatusInt() != 7) or ($task->get_TaskSuccess() != 1)) {
    if (!$success) {
        # The task.LastErrorText applies to the Wait method call.
        print $task->lastErrorText() . "\r\n";
    }
    else {
        # The ResultErrorText applies to the underlying task method call (i.e. the AcceptNextConnection)
        print $task->status() . "\r\n";
        print $task->resultErrorText() . "\r\n";
    }

    exit;
}

# If we get to this point, a connection on listenSock was accepted, and the redirected POST
# is waiting to be read on the connected socket.
# The POST we are going to read contains the following:

# POST /myapp/ HTTP/1.1
# Host: localhost
# Content-Type: application/x-www-form-urlencoded
# 
# id_token=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsIng1dCI6Ik1uQ19WWmNB...&state=12345

# But first.. we no longer need the listen socket...
# Stop listening on port 3017.
$listenSock->Close(10);

# We're acting as a temporary web server to receive this one redirected HTTP request..
# Read the start line of the request.. (i.e. the "POST /myapp/ HTTP/1.1")
$startLine = $browserSock->receiveUntilMatch("\r\n");
if ($browserSock->get_LastMethodSuccess() == 0) {
    print $browserSock->lastErrorText() . "\r\n";
    exit;
}

# Read the request header.
$requestHeader = $browserSock->receiveUntilMatch("\r\n\r\n");
if ($browserSock->get_LastMethodSuccess() == 0) {
    print $browserSock->lastErrorText() . "\r\n";
    exit;
}

print $requestHeader . "\r\n";
print "----" . "\r\n";

# Read the body.
# The body will contain "id_token= eyJ......"
$sbRequestBody = chilkat::CkStringBuilder->new();
$success = $browserSock->ReceiveSb($sbRequestBody);
if ($success == 0) {
    print $browserSock->lastErrorText() . "\r\n";
    exit;
}

print $sbRequestBody->getAsString() . "\r\n";

# Given that we're acting as a web server, we must send a response..
# We can now send our HTTP response.
$sbResponseHtml = chilkat::CkStringBuilder->new();
$sbResponseHtml->Append("<html><body><p>Thank you!</b></body</html>");

$sbResponse = chilkat::CkStringBuilder->new();
$sbResponse->Append("HTTP/1.1 200 OK\r\n");
$sbResponse->Append("Content-Length: ");
$sbResponse->AppendInt($sbResponseHtml->get_Length());
$sbResponse->Append("\r\n");
$sbResponse->Append("Content-Type: text/html\r\n");
$sbResponse->Append("\r\n");
$sbResponse->AppendSb($sbResponseHtml);

$browserSock->SendString($sbResponse->getAsString());
$browserSock->Close(50);

# Get the id_token from the sbRequestBody that we just received.
# (Remember, we're acting as the web server, thus we received the redirect request..)
$hashTab = chilkat::CkHashtable->new();
$hashTab->AddQueryParams($sbRequestBody->getAsString());

# See https://docs.microsoft.com/en-us/azure/active-directory/develop/id-tokens#validating-an-id-token
# for more information about ID tokens..
$idToken = $hashTab->lookupStr("id_token");

$jwt = chilkat::CkJwt->new();

# Let's see if the time constraints, if any, are valid.
# The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
# If the current system time is before the "nbf" time, or after the "exp" time,
# then IsTimeValid will return false/0.
# Also, we'll allow a leeway of 60 seconds to account for any clock skew.
# Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
$leeway = 60;
$bTimeValid = $jwt->IsTimeValid($idToken,$leeway);
print "time constraints valid: " . $bTimeValid . "\r\n";

# Now let's recover the original claims JSON (the payload).
$payload = $jwt->getPayload($idToken);
# The payload will likely be in compact form:
print $payload . "\r\n";

# We can format for human viewing by loading it into Chilkat's JSON object
# and emit.
$json = chilkat::CkJsonObject->new();
$success = $json->Load($payload);
$json->put_EmitCompact(0);
print $json->emit() . "\r\n";

# Sample output:

# {
#   "aud": "f125d695-c50e-456e-a579-a486f06d1213",
#   "iss": "https://login.microsoftonline.com/6d8ddd66-68d1-43b0-af5c-e31b4b7dd5cd/v2.0",
#   "iat": 1626535322,
#   "nbf": 1626535322,
#   "exp": 1626539222,
#   "aio": "AWQAm/8TAAAAHQncmY0VvhgyMIhfleHX3DjsGfmlPM1CopkJ3mPnBUnCxrJ0ubruaACEhwGO7NsoHBhqFEzRzPxOq7MtuGVFsql+qJKZx8vQCszKYEPX9Wb3b5+d5KJTABHCIH48bTFd",
#   "idp": "https://sts.windows.net/9188040d-6c67-4c5b-b112-36a304b66dad/",
#   "nonce": "1519043321",
#   "rh": "0.ARgAZt2NbdFosEOvXOMbS33VzZXWJfEOxW5FpXmkhvBtEhMYALQ.",
#   "sub": "RMIZlHJ7hfsJmL8Qq3h6M0nPi4g-HEavnAFgxzaT2KM",
#   "tid": "6d8ddd66-68d1-43b0-af5c-e31b4b7dd5cd",
#   "uti": "-BXGHxvfREW-r9HI5NBiAA",
#   "ver": "2.0"
# }

# We can recover the original JOSE header in the same way:
$joseHeader = $jwt->getHeader($idToken);
# The payload will likely be in compact form:
print $joseHeader . "\r\n";

# We can format for human viewing by loading it into Chilkat's JSON object
# and emit.
$jsonJoseHeader = chilkat::CkJsonObject->new();
$success = $jsonJoseHeader->Load($joseHeader);
$jsonJoseHeader->put_EmitCompact(0);
print $jsonJoseHeader->emit() . "\r\n";

# Sample output:

# {
#   "typ": "JWT",
#   "alg": "RS256",
#   "kid": "nOo3ZDrODXEK1jKWhXslHR_KXEg"
# }

# Finally, we need to fetch the JSON Web Key Sets from the jwks_uri
# and use it to verify the id_token's RSA signature.
$sbJwks = chilkat::CkStringBuilder->new();
$http = chilkat::CkHttp->new();
$success = $http->QuickGetSb($jwks_uri,$sbJwks);
if ($success == 0) {
    print $http->lastErrorText() . "\r\n";
    exit;
}

$jwkset = chilkat::CkJsonObject->new();
$success = $jwkset->LoadSb($sbJwks);
$jwkset->put_EmitCompact(0);
print $jwkset->emit() . "\r\n";

# A sample jwkset:

# {
#   "keys": [
#     {
#       "kty": "RSA",
#       "use": "sig",
#       "kid": "nOo3ZDrODXEK1jKWhXslHR_KXEg",
#       "x5t": "nOo3ZDrODXEK1jKWhXslHR_KXEg",
#       "n": "oaLLT9hkcSj ... NVrZdUdTBQ",
#       "e": "AQAB",
#       "x5c": [
#         "MIIDBTC ... MRku44Dw7R"
#       ],
#       "issuer": "https://login.microsoftonline.com/6d8ddd66-68d1-43b0-af5c-e31b4b7dd5cd/v2.0"
#     },
#     {
#       "kty": "RSA",
#       "use": "sig",
#       "kid": "l3sQ-50cCH4xBVZLHTGwnSR7680",
#       "x5t": "l3sQ-50cCH4xBVZLHTGwnSR7680",
#       "n": "sfsXMXW ... AYkwb6xUQ",
#       "e": "AQAB",
#       "x5c": [
#         "MIIDBTCCA ... BWrh+/vJ"
#       ],
#       "issuer": "https://login.microsoftonline.com/6d8ddd66-68d1-43b0-af5c-e31b4b7dd5cd/v2.0"
#     },
#     {
#       "kty": "RSA",
#       "use": "sig",
#       "kid": "DqUu8gf-nAgcyjP3-SuplNAXAnc",
#       "x5t": "DqUu8gf-nAgcyjP3-SuplNAXAnc",
#       "n": "1n7-nWSL ... V3pFWhQ",
#       "e": "AQAB",
#       "x5c": [
#         "MIIC8TC ... 9pIcnkPQ=="
#       ],
#       "issuer": "https://login.microsoftonline.com/6d8ddd66-68d1-43b0-af5c-e31b4b7dd5cd/v2.0"
#     },
#     {
#       "kty": "RSA",
#       "use": "sig",
#       "kid": "OzZ5Dbmcso9Qzt2ModGmihg30Bo",
#       "x5t": "OzZ5Dbmcso9Qzt2ModGmihg30Bo",
#       "n": "01re9a2BU ... 5OzQ6Q",
#       "e": "AQAB",
#       "x5c": [
#         "MIIC8TC ... YmwJ6sDdRvQ=="
#       ],
#       "issuer": "https://login.microsoftonline.com/6d8ddd66-68d1-43b0-af5c-e31b4b7dd5cd/v2.0"
#     }
#   ]
# }

# We should have an RSA key with kid matching the kid from the joseHeader..
$kid = $jsonJoseHeader->stringOf("kid");

# Find the RSA key with the specified key id
# jwk is a JsonObject
$jwk = $jwkset->FindRecord("keys","kid",$kid,1);
if ($jwkset->get_LastMethodSuccess() == 0) {
    print "Failed to find a matching RSA key in the JWK key set..." . "\r\n";
    exit;
}

$pubkey = chilkat::CkPublicKey->new();

$success = $pubkey->LoadFromString($jwk->emit());
if ($success == 0) {
    print $pubkey->lastErrorText() . "\r\n";
    print $jwk->emit() . "\r\n";
}
else {
    $verified = $jwt->VerifyJwtPk($idToken,$pubkey);
    print "Verified: " . $verified . "\r\n";
}