(Xojo Plugin) 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 Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

Dim cert As New Chilkat.Cert
Dim success As Boolean
success = cert.LoadFromFile("qa_data/certs_and_keys/ING/example_client_tls.cer")
If (success = False) Then
    System.DebugLog(cert.LastErrorText)
    Return
End If

Dim bdPrivKey As New Chilkat.BinData
success = bdPrivKey.LoadFile("qa_data/certs_and_keys/ING/example_client_tls.key")
If (success = False) Then
    System.DebugLog("Failed to load example_client_tls.key")
    Return
End If

// 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.

Dim privKey As New Chilkat.PrivateKey
success = privKey.LoadAnyFormat(bdPrivKey,"")
If (success = False) Then
    System.DebugLog(privKey.LastErrorText)
    Return
End If

// Associate the private key with the certificate.
success = cert.SetPrivateKey(privKey)
If (success = False) Then
    System.DebugLog(cert.LastErrorText)
    Return
End If

Dim http As New Chilkat.Http

success = http.SetSslClientCert(cert)
If (success = False) Then
    System.DebugLog(http.LastErrorText)
    Return
End If

// 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
Dim crypt As New Chilkat.Crypt2
crypt.HashAlgorithm = "SHA256"
crypt.EncodingMode = "base64"
Dim payload As String
payload = "grant_type=client_credentials"
Dim payloadDigest As String
payloadDigest = crypt.HashStringENC(payload)

// 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")  
Dim dt As New Chilkat.CkDateTime
success = dt.SetFromCurrentSystemTime()
// The desire date/time format is the "RFC822" format.
http.SetRequestHeader "Date",dt.GetAsRfc822(False)

// 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`

Dim httpMethod As String
httpMethod = "POST"
Dim reqPath As String
reqPath = "/oauth2/token"

Dim sbStringToSign As New Chilkat.StringBuilder
success = sbStringToSign.Append("(request-target): ")
success = sbStringToSign.Append(httpMethod)
success = sbStringToSign.ToLowercase()
success = sbStringToSign.Append(" ")
success = sbStringToSign.AppendLine(reqPath,False)

success = sbStringToSign.Append("date: ")
success = sbStringToSign.AppendLine(dt.GetAsRfc822(False),False)

success = sbStringToSign.Append("digest: SHA-256=")
success = sbStringToSign.Append(payloadDigest)

Dim signingPrivKey As New Chilkat.PrivateKey
success = signingPrivKey.LoadPemFile("qa_data/certs_and_keys/ING/example_client_signing.key")
If (success = False) Then
    System.DebugLog(signingPrivKey.LastErrorText)
    Return
End If

Dim rsa As New Chilkat.Rsa
success = rsa.ImportPrivateKeyObj(signingPrivKey)
If (success = False) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

rsa.EncodingMode = "base64"
Dim b64Signature As String
b64Signature = rsa.SignStringENC(sbStringToSign.GetAsString(),"SHA256")

Dim sbAuthHdrVal As New Chilkat.StringBuilder
success = sbAuthHdrVal.Append("Signature keyId=""e77d776b-90af-4684-bebc-521e5b2614dd"",")
success = sbAuthHdrVal.Append("algorithm=""rsa-sha256"",")
success = sbAuthHdrVal.Append("headers=""(request-target) date digest"",")
success = sbAuthHdrVal.Append("signature=""")
success = sbAuthHdrVal.Append(b64Signature)
success = sbAuthHdrVal.Append("""")

Dim sbDigestHdrVal As New Chilkat.StringBuilder
success = sbDigestHdrVal.Append("SHA-256=")
success = sbDigestHdrVal.Append(payloadDigest)

// 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"

Dim req As New Chilkat.HttpRequest
req.AddParam "grant_type","client_credentials"
req.AddHeader "Accept","application/json"
req.AddHeader "Date",dt.GetAsRfc822(False)
req.AddHeader "Digest",sbDigestHdrVal.GetAsString()
req.AddHeader "Authorization",sbAuthHdrVal.GetAsString()
Dim resp As Chilkat.HttpResponse
resp = http.PostUrlEncoded("https://api.sandbox.ing.com/oauth2/token",req)
If (http.LastMethodSuccess = False) Then
    System.DebugLog(http.LastErrorText)
    Return
End If

// If successful, the status code = 200
System.DebugLog("Response Status Code: " + Str(resp.StatusCode))
System.DebugLog(resp.BodyStr)

Dim json As New Chilkat.JsonObject
success = json.Load(resp.BodyStr)

json.EmitCompact = False
System.DebugLog(json.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

Dim kty As String
Dim n As String
Dim e As String
Dim use As String
Dim alg As String
Dim x5t As String

Dim access_token As String
access_token = json.StringOf("access_token")
Dim expires_in As Int32
expires_in = json.IntOf("expires_in")
Dim scope As String
scope = json.StringOf("scope")
Dim token_type As String
token_type = json.StringOf("token_type")
Dim client_id As String
client_id = json.StringOf("client_id")
Dim i As Int32
i = 0
Dim count_i As Int32
count_i = json.SizeOfArray("keys")
While i < count_i
    json.I = i
    kty = json.StringOf("keys[i].kty")
    n = json.StringOf("keys[i].n")
    e = json.StringOf("keys[i].e")
    use = json.StringOf("keys[i].use")
    alg = json.StringOf("keys[i].alg")
    x5t = json.StringOf("keys[i].x5t")
    i = i + 1
Wend

// 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.
success = json.WriteFile("qa_data/tokens/ing_access_token.json")