(Visual FoxPro) ING Open Banking OAuth2 Client Credentials

Demonstrates how to get an access token for the ING Open Banking APIs using client credentials.

For more information, see https://developer.ing.com/openbanking/get-started/openbanking

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

LOCAL loCert
LOCAL lnSuccess
LOCAL loBdPrivKey
LOCAL loPrivKey
LOCAL loHttp
LOCAL loCrypt
LOCAL lcPayload
LOCAL lcPayloadDigest
LOCAL loDt
LOCAL lcHttpMethod
LOCAL lcReqPath
LOCAL loSbStringToSign
LOCAL loSigningPrivKey
LOCAL loRsa
LOCAL lcB64Signature
LOCAL loSbAuthHdrVal
LOCAL loSbDigestHdrVal
LOCAL loReq
LOCAL loResp
LOCAL loJson
LOCAL lcKty
LOCAL n
LOCAL e
LOCAL lcUse
LOCAL lcAlg
LOCAL lcX5t
LOCAL lcAccess_token
LOCAL lnExpires_in
LOCAL lcScope
LOCAL lcToken_type
LOCAL lcClient_id
LOCAL i
LOCAL lnCount_i

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

loCert = CreateObject('Chilkat_9_5_0.Cert')
lnSuccess = loCert.LoadFromFile("qa_data/certs_and_keys/ING/example_client_tls.cer")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loCert
    CANCEL
ENDIF

loBdPrivKey = CreateObject('Chilkat_9_5_0.BinData')
lnSuccess = loBdPrivKey.LoadFile("qa_data/certs_and_keys/ING/example_client_tls.key")
IF (lnSuccess = 0) THEN
    ? "Failed to load example_client_tls.key"
    RELEASE loCert
    RELEASE loBdPrivKey
    CANCEL
ENDIF

* The OAuth 2.0 client_id for these certificates is e77d776b-90af-4684-bebc-521e5b2614dd. 
* Please note down this client_id since you will need it in the next steps to call the API.

loPrivKey = CreateObject('Chilkat_9_5_0.PrivateKey')
lnSuccess = loPrivKey.LoadAnyFormat(loBdPrivKey,"")
IF (lnSuccess = 0) THEN
    ? loPrivKey.LastErrorText
    RELEASE loCert
    RELEASE loBdPrivKey
    RELEASE loPrivKey
    CANCEL
ENDIF

* Associate the private key with the certificate.
lnSuccess = loCert.SetPrivateKey(loPrivKey)
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loCert
    RELEASE loBdPrivKey
    RELEASE loPrivKey
    CANCEL
ENDIF

loHttp = CreateObject('Chilkat_9_5_0.Http')

lnSuccess = loHttp.SetSslClientCert(loCert)
IF (lnSuccess = 0) THEN
    ? loHttp.LastErrorText
    RELEASE loCert
    RELEASE loBdPrivKey
    RELEASE loPrivKey
    RELEASE loHttp
    CANCEL
ENDIF

* Calculate the Digest and add the "Digest" header.  Do the equivalent of this:
* payload="grant_type=client_credentials"
* payloadDigest=`echo -n "$payload" | openssl dgst -binary -sha256 | openssl base64`
* digest=SHA-256=$payloadDigest
loCrypt = CreateObject('Chilkat_9_5_0.Crypt2')
loCrypt.HashAlgorithm = "SHA256"
loCrypt.EncodingMode = "base64"
lcPayload = "grant_type=client_credentials"
lcPayloadDigest = loCrypt.HashStringENC(lcPayload)

* Calculate the current date/time and add the Date header.  
* reqDate=$(LC_TIME=en_US.UTF-8 date -u "+%a, %d %b %Y %H:%M:%S GMT")  
loDt = CreateObject('Chilkat_9_5_0.CkDateTime')
loDt.SetFromCurrentSystemTime()
* The desire date/time format is the "RFC822" format.
loHttp.SetRequestHeader("Date",loDt.GetAsRfc822(0))

* Calculate signature for signing your request
* Duplicate the following code:

* 	httpMethod="post"
* 	reqPath="/oauth2/token"
* 	signingString="(request-target): $httpMethod $reqPath
* 	date: $reqDate
* 	digest: $digest"
* 	signature=`printf "$signingString" | openssl dgst -sha256 -sign "${certPath}example_client_signing.key" -passin "pass:changeit" | openssl base64 -A`

lcHttpMethod = "POST"
lcReqPath = "/oauth2/token"

loSbStringToSign = CreateObject('Chilkat_9_5_0.StringBuilder')
loSbStringToSign.Append("(request-target): ")
loSbStringToSign.Append(lcHttpMethod)
loSbStringToSign.ToLowercase()
loSbStringToSign.Append(" ")
loSbStringToSign.AppendLine(lcReqPath,0)

loSbStringToSign.Append("date: ")
loSbStringToSign.AppendLine(loDt.GetAsRfc822(0),0)

loSbStringToSign.Append("digest: SHA-256=")
loSbStringToSign.Append(lcPayloadDigest)

loSigningPrivKey = CreateObject('Chilkat_9_5_0.PrivateKey')
lnSuccess = loSigningPrivKey.LoadPemFile("qa_data/certs_and_keys/ING/example_client_signing.key")
IF (lnSuccess = 0) THEN
    ? loSigningPrivKey.LastErrorText
    RELEASE loCert
    RELEASE loBdPrivKey
    RELEASE loPrivKey
    RELEASE loHttp
    RELEASE loCrypt
    RELEASE loDt
    RELEASE loSbStringToSign
    RELEASE loSigningPrivKey
    CANCEL
ENDIF

loRsa = CreateObject('Chilkat_9_5_0.Rsa')
lnSuccess = loRsa.ImportPrivateKeyObj(loSigningPrivKey)
IF (lnSuccess = 0) THEN
    ? loRsa.LastErrorText
    RELEASE loCert
    RELEASE loBdPrivKey
    RELEASE loPrivKey
    RELEASE loHttp
    RELEASE loCrypt
    RELEASE loDt
    RELEASE loSbStringToSign
    RELEASE loSigningPrivKey
    RELEASE loRsa
    CANCEL
ENDIF

loRsa.EncodingMode = "base64"
lcB64Signature = loRsa.SignStringENC(loSbStringToSign.GetAsString(),"SHA256")

loSbAuthHdrVal = CreateObject('Chilkat_9_5_0.StringBuilder')
loSbAuthHdrVal.Append('Signature keyId="e77d776b-90af-4684-bebc-521e5b2614dd",')
loSbAuthHdrVal.Append('algorithm="rsa-sha256",')
loSbAuthHdrVal.Append('headers="(request-target) date digest",')
loSbAuthHdrVal.Append('signature="')
loSbAuthHdrVal.Append(lcB64Signature)
loSbAuthHdrVal.Append('"')

loSbDigestHdrVal = CreateObject('Chilkat_9_5_0.StringBuilder')
loSbDigestHdrVal.Append("SHA-256=")
loSbDigestHdrVal.Append(lcPayloadDigest)

* Do the following CURL statement:

* 	curl -i -X POST "${httpHost}${reqPath}" \
* 	-H 'Accept: application/json' \
* 	-H 'Content-Type: application/x-www-form-urlencoded' \
* 	-H "Digest: ${digest}" \
* 	-H "Date: ${reqDate}" \
* 	-H "authorization: Signature keyId=\"$keyId\",algorithm=\"rsa-sha256\",headers=\"(request-target) date digest\",signature=\"$signature\"" \
* 	-d "${payload}" \
* 	--cert "${certPath}tlsCert.crt" \
* 	--key "${certPath}tlsCert.key"

loReq = CreateObject('Chilkat_9_5_0.HttpRequest')
loReq.AddParam("grant_type","client_credentials")
loReq.AddHeader("Accept","application/json")
loReq.AddHeader("Date",loDt.GetAsRfc822(0))
loReq.AddHeader("Digest",loSbDigestHdrVal.GetAsString())
loReq.AddHeader("Authorization",loSbAuthHdrVal.GetAsString())
loResp = loHttp.PostUrlEncoded("https://api.sandbox.ing.com/oauth2/token",loReq)
IF (loHttp.LastMethodSuccess = 0) THEN
    ? loHttp.LastErrorText
    RELEASE loCert
    RELEASE loBdPrivKey
    RELEASE loPrivKey
    RELEASE loHttp
    RELEASE loCrypt
    RELEASE loDt
    RELEASE loSbStringToSign
    RELEASE loSigningPrivKey
    RELEASE loRsa
    RELEASE loSbAuthHdrVal
    RELEASE loSbDigestHdrVal
    RELEASE loReq
    CANCEL
ENDIF

* If successful, the status code = 200
? "Response Status Code: " + STR(loResp.StatusCode)
? loResp.BodyStr

loJson = CreateObject('Chilkat_9_5_0.JsonObject')
loJson.Load(loResp.BodyStr)

RELEASE loResp

loJson.EmitCompact = 0
? loJson.Emit()

* A successful response contains an access token such as:
* {
*   "access_token": "eyJhbGc ... bxI_SoPOBH9xmoM",
*   "expires_in": 905,
*   "scope": "payment-requests:view payment-requests:create payment-requests:close greetings:view virtual-ledger-accounts:fund-reservation:create virtual-ledger-accounts:fund-reservation:delete virtual-ledger-accounts:balance:view",
*   "token_type": "Bearer",
*   "keys": [
*     {
*       "kty": "RSA",
*       "n": "3l3rdz4...04VPkdV",
*       "e": "AQAB",
*       "use": "sig",
*       "alg": "RS256",
*       "x5t": "3c396700fc8cd709cf9cb5452a22bcde76985851"
*     }
*   ],
*   "client_id": "e77d776b-90af-4684-bebc-521e5b2614dd"
* }

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

lcAccess_token = loJson.StringOf("access_token")
lnExpires_in = loJson.IntOf("expires_in")
lcScope = loJson.StringOf("scope")
lcToken_type = loJson.StringOf("token_type")
lcClient_id = loJson.StringOf("client_id")
i = 0
lnCount_i = loJson.SizeOfArray("keys")
DO WHILE i < lnCount_i
    loJson.I = i
    lcKty = loJson.StringOf("keys[i].kty")
    n = loJson.StringOf("keys[i].n")
    e = loJson.StringOf("keys[i].e")
    lcUse = loJson.StringOf("keys[i].use")
    lcAlg = loJson.StringOf("keys[i].alg")
    lcX5t = loJson.StringOf("keys[i].x5t")
    i = i + 1
ENDDO

* This example will save the JSON containing the access key to a file so that
* a subsequent example can load it and then use the access key for a request, such as to create a payment request.
loJson.WriteFile("qa_data/tokens/ing_access_token.json")

RELEASE loCert
RELEASE loBdPrivKey
RELEASE loPrivKey
RELEASE loHttp
RELEASE loCrypt
RELEASE loDt
RELEASE loSbStringToSign
RELEASE loSigningPrivKey
RELEASE loRsa
RELEASE loSbAuthHdrVal
RELEASE loSbDigestHdrVal
RELEASE loReq
RELEASE loJson