(PureBasic) 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

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkJsonObject.pb"
IncludeFile "CkJwt.pb"
IncludeFile "CkPrivateKey.pb"
IncludeFile "CkHttp.pb"
IncludeFile "CkHttpRequest.pb"
IncludeFile "CkHttpResponse.pb"

Procedure ChilkatExample()

    ; 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.
    privkey.i = CkPrivateKey::ckCreate()
    If privkey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkPrivateKey::ckLoadPemFile(privkey,"qa_data/pem/abnAmroPrivateKey.pem")
    If success = 0
        Debug CkPrivateKey::ckLastErrorText(privkey)
        CkPrivateKey::ckDispose(privkey)
        ProcedureReturn
    EndIf

    ; Create the JWT.
    jwt.i = CkJwt::ckCreate()
    If jwt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Create the header:
    ; {
    ;     "typ": "JWT",
    ;     "alg": "RS256"
    ; }
    jsonHeader.i = CkJsonObject::ckCreate()
    If jsonHeader.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(jsonHeader,"typ","JWT")
    CkJsonObject::ckUpdateString(jsonHeader,"alg","RS256")

    ; Create the payload:
    ; {
    ;     "nbf": 1499947668,
    ;     "exp": 1499948668,
    ;     "iss": "me",
    ;     "sub": "anApiKey",
    ;     "aud": "https://auth-sandbox.abnamro.com/oauth/token"
    ; }
    jsonPayload.i = CkJsonObject::ckCreate()
    If jsonPayload.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    curDateTime.i = CkJwt::ckGenNumericDate(jwt,0)

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

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

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

    ; Produce the smallest possible JWT:
    CkJwt::setCkAutoCompact(jwt, 1)

    jwtStr.s = CkJwt::ckCreateJwtPk(jwt,CkJsonObject::ckEmit(jsonHeader),CkJsonObject::ckEmit(jsonPayload),privkey)
    If CkJwt::ckLastMethodSuccess(jwt) <> 1
        Debug CkJwt::ckLastErrorText(jwt)
        CkPrivateKey::ckDispose(privkey)
        CkJwt::ckDispose(jwt)
        CkJsonObject::ckDispose(jsonHeader)
        CkJsonObject::ckDispose(jsonPayload)
        ProcedureReturn
    EndIf

    http.i = CkHttp::ckCreate()
    If http.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    req.i = CkHttpRequest::ckCreate()
    If req.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkHttpRequest::ckAddParam(req,"client_assertion_type","urn:ietf:params:oauth:client-assertion-type:jwt-bearer")
    CkHttpRequest::ckAddParam(req,"grant_type","client_credentials")
    CkHttpRequest::ckAddParam(req,"client_assertion",jwtStr)
    CkHttpRequest::ckAddParam(req,"scope","tikkie")

    resp.i = CkHttp::ckPostUrlEncoded(http,"https://api-sandbox.abnamro.com/v1/oauth/token",req)
    If CkHttp::ckLastMethodSuccess(http) = 0
        Debug CkHttp::ckLastErrorText(http)
        CkPrivateKey::ckDispose(privkey)
        CkJwt::ckDispose(jwt)
        CkJsonObject::ckDispose(jsonHeader)
        CkJsonObject::ckDispose(jsonPayload)
        CkHttp::ckDispose(http)
        CkHttpRequest::ckDispose(req)
        ProcedureReturn
    EndIf

    If CkHttpResponse::ckStatusCode(resp) <> 200
        Debug CkHttpResponse::ckBodyStr(resp)
        CkHttpResponse::ckDispose(resp)

        CkPrivateKey::ckDispose(privkey)
        CkJwt::ckDispose(jwt)
        CkJsonObject::ckDispose(jsonHeader)
        CkJsonObject::ckDispose(jsonPayload)
        CkHttp::ckDispose(http)
        CkHttpRequest::ckDispose(req)
        ProcedureReturn
    EndIf

    ; 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}"
    ; }
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckLoad(json,CkHttpResponse::ckBodyStr(resp))
    Debug "access_token: " + CkJsonObject::ckStringOf(json,"access_token")
    Debug "token_type: " + CkJsonObject::ckStringOf(json,"token_type")
    Debug "expires_in: " + CkJsonObject::ckStringOf(json,"expires_in")
    Debug "scope: " + CkJsonObject::ckStringOf(json,"scope")

    CkHttpResponse::ckDispose(resp)



    CkPrivateKey::ckDispose(privkey)
    CkJwt::ckDispose(jwt)
    CkJsonObject::ckDispose(jsonHeader)
    CkJsonObject::ckDispose(jsonPayload)
    CkHttp::ckDispose(http)
    CkHttpRequest::ckDispose(req)
    CkJsonObject::ckDispose(json)


    ProcedureReturn
EndProcedure