(Perl) 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 Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux

use chilkat();

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

$cert = chilkat::CkCert->new();
$success = $cert->LoadFromFile("qa_data/certs_and_keys/ING/example_client_tls.cer");
if ($success == 0) {
    print $cert->lastErrorText() . "\r\n";
    exit;
}

$bdPrivKey = chilkat::CkBinData->new();
$success = $bdPrivKey->LoadFile("qa_data/certs_and_keys/ING/example_client_tls.key");
if ($success == 0) {
    print "Failed to load example_client_tls.key" . "\r\n";
    exit;
}

# 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.

$privKey = chilkat::CkPrivateKey->new();
$success = $privKey->LoadAnyFormat($bdPrivKey,"");
if ($success == 0) {
    print $privKey->lastErrorText() . "\r\n";
    exit;
}

# Associate the private key with the certificate.
$success = $cert->SetPrivateKey($privKey);
if ($success == 0) {
    print $cert->lastErrorText() . "\r\n";
    exit;
}

$http = chilkat::CkHttp->new();

$success = $http->SetSslClientCert($cert);
if ($success == 0) {
    print $http->lastErrorText() . "\r\n";
    exit;
}

# 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
$crypt = chilkat::CkCrypt2->new();
$crypt->put_HashAlgorithm("SHA256");
$crypt->put_EncodingMode("base64");
$payload = "grant_type=client_credentials";
$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")  
$dt = chilkat::CkDateTime->new();
$dt->SetFromCurrentSystemTime();
# The desire date/time format is the "RFC822" format.
$http->SetRequestHeader("Date",$dt->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`

$httpMethod = "POST";
$reqPath = "/oauth2/token";

$sbStringToSign = chilkat::CkStringBuilder->new();
$sbStringToSign->Append("(request-target): ");
$sbStringToSign->Append($httpMethod);
$sbStringToSign->ToLowercase();
$sbStringToSign->Append(" ");
$sbStringToSign->AppendLine($reqPath,0);

$sbStringToSign->Append("date: ");
$sbStringToSign->AppendLine($dt->getAsRfc822(0),0);

$sbStringToSign->Append("digest: SHA-256=");
$sbStringToSign->Append($payloadDigest);

$signingPrivKey = chilkat::CkPrivateKey->new();
$success = $signingPrivKey->LoadPemFile("qa_data/certs_and_keys/ING/example_client_signing.key");
if ($success == 0) {
    print $signingPrivKey->lastErrorText() . "\r\n";
    exit;
}

$rsa = chilkat::CkRsa->new();
$success = $rsa->ImportPrivateKeyObj($signingPrivKey);
if ($success == 0) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

$rsa->put_EncodingMode("base64");
$b64Signature = $rsa->signStringENC($sbStringToSign->getAsString(),"SHA256");

$sbAuthHdrVal = chilkat::CkStringBuilder->new();
$sbAuthHdrVal->Append("Signature keyId=\"e77d776b-90af-4684-bebc-521e5b2614dd\",");
$sbAuthHdrVal->Append("algorithm=\"rsa-sha256\",");
$sbAuthHdrVal->Append("headers=\"(request-target) date digest\",");
$sbAuthHdrVal->Append("signature=\"");
$sbAuthHdrVal->Append($b64Signature);
$sbAuthHdrVal->Append("\"");

$sbDigestHdrVal = chilkat::CkStringBuilder->new();
$sbDigestHdrVal->Append("SHA-256=");
$sbDigestHdrVal->Append($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"

$req = chilkat::CkHttpRequest->new();
$req->AddParam("grant_type","client_credentials");
$req->AddHeader("Accept","application/json");
$req->AddHeader("Date",$dt->getAsRfc822(0));
$req->AddHeader("Digest",$sbDigestHdrVal->getAsString());
$req->AddHeader("Authorization",$sbAuthHdrVal->getAsString());
# resp is a HttpResponse
$resp = $http->PostUrlEncoded("https://api.sandbox.ing.com/oauth2/token",$req);
if ($http->get_LastMethodSuccess() == 0) {
    print $http->lastErrorText() . "\r\n";
    exit;
}

# If successful, the status code = 200
print "Response Status Code: " . $resp->get_StatusCode() . "\r\n";
print $resp->bodyStr() . "\r\n";

$json = chilkat::CkJsonObject->new();
$json->Load($resp->bodyStr());

$json->put_EmitCompact(0);
print $json->emit() . "\r\n";

# 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

$access_token = $json->stringOf("access_token");
$expires_in = $json->IntOf("expires_in");
$scope = $json->stringOf("scope");
$token_type = $json->stringOf("token_type");
$client_id = $json->stringOf("client_id");
$i = 0;
$count_i = $json->SizeOfArray("keys");
while ($i < $count_i) {
    $json->put_I($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;
}

# 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.
$json->WriteFile("qa_data/tokens/ing_access_token.json");