(Visual FoxPro) PRODA Get OAuth2 Access Token using JWT

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Demonstrates how to get an OAuth2 access token for the PRODA Australian Government Online Services using a JWT.

For more information, see https://www.servicesaustralia.gov.au/organisations/business/services/proda-provider-digital-access

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loPrivKey
LOCAL lnSuccess
LOCAL loJwt
LOCAL loJose
LOCAL loClaims
LOCAL lnCurDateTime
LOCAL lcJwtToken
LOCAL loHttp
LOCAL loReq
LOCAL loResp

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

* First create a JWT to be sent in the POST to https://vnd.proda.humanservices.gov.au/mga/sps/oauth/oauth20/token

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.PrivateKey')
loPrivKey = CreateObject('Chilkat.PrivateKey')

* Load an RSA private key from a PEM file.
* Chilkat provides alternative methods to load from other formats, or to load from a string or binary data.
lnSuccess = loPrivKey.LoadEncryptedPemFile("qa_data/pem/rsa_passwd.pem","passwd")
IF (lnSuccess <> 1) THEN
    ? loPrivKey.LastErrorText
    RELEASE loPrivKey
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jwt')
loJwt = CreateObject('Chilkat.Jwt')

* Build the JOSE header
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJose = CreateObject('Chilkat.JsonObject')
* Use RS256.  Pass the string "RS384" or "RS512" to use RSA with SHA-384 or SHA-512.
lnSuccess = loJose.AppendString("alg","RS256")
lnSuccess = loJose.AppendString("typ","JWT")
lnSuccess = loJose.AppendString("kid","test-device")

* Now build the JWT claims (also known as the payload)
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loClaims = CreateObject('Chilkat.JsonObject')
lnSuccess = loClaims.AppendString("iss","9646844092")
lnSuccess = loClaims.AppendString("sub","test-device")
lnSuccess = loClaims.AppendString("aud","https://proda.humanservices.gov.au")

* Set the timestamp of when the JWT was created to now.
lnCurDateTime = loJwt.GenNumericDate(0)
lnSuccess = loClaims.AddIntAt(-1,"iat",lnCurDateTime)

* Set the timestamp defining an expiration time (end time) for the token
* to be now + 1 hour (3600 seconds)
lnSuccess = loClaims.AddIntAt(-1,"exp",lnCurDateTime + 3600)

* Produce the smallest possible JWT:
loJwt.AutoCompact = 1

* Create the JWT token.  This is where the RSA signature is created.
lcJwtToken = loJwt.CreateJwtPk(loJose.Emit(),loClaims.Emit(),loPrivKey)

* ---------------------------------------------------------------------
* Build and send the POST, which should look something like this:

* POST https://vnd.proda.humanservices.gov.au/mga/sps/oauth/oauth20/token HTTP/1.1
* Content-Type: application/x-www-form-urlencoded
* Content-Length: 666
* Host: vnd.proda.humanservices.gov.au
* 
* grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt-bearer&assertion=<jwt>&client_id=VendorClient03

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Http')
loHttp = CreateObject('Chilkat.Http')

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.HttpRequest')
loReq = CreateObject('Chilkat.HttpRequest')

* Add the request params.
loReq.AddParam("grant_type","urn:ietf:params:oauth:grant-type:jwt-bearer")
loReq.AddParam("assertion",lcJwtToken)
loReq.AddParam("client_id","VendorClient03")

* Send the POST
* Chilkat automatically adds the Content-Type (which is application/x-www-form-urlencoded for the PostUrlEncoded method)
* Chilkat also automatically adds the Host and Content-Length headers.

loResp = loHttp.PostUrlEncoded("https://vnd.proda.humanservices.gov.au/mga/sps/oauth/oauth20/token",loReq)
IF (loHttp.LastMethodSuccess <> 1) THEN
    ? loHttp.LastErrorText
    RELEASE loPrivKey
    RELEASE loJwt
    RELEASE loJose
    RELEASE loClaims
    RELEASE loHttp
    RELEASE loReq
    CANCEL
ENDIF

? "Response status code = " + STR(loResp.StatusCode)
? "Response body:"
? loResp.BodyStr

RELEASE loResp

RELEASE loPrivKey
RELEASE loJwt
RELEASE loJose
RELEASE loClaims
RELEASE loHttp
RELEASE loReq