(Ruby) 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 Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require '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 == false)
    print cert.lastErrorText() + "\n";
    exit
end

bdPrivKey = Chilkat::CkBinData.new()
success = bdPrivKey.LoadFile("qa_data/certs_and_keys/ING/example_client_tls.key")
if (success == false)
    print "Failed to load example_client_tls.key" + "\n";
    exit
end

# 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 == false)
    print privKey.lastErrorText() + "\n";
    exit
end

# Associate the private key with the certificate.
success = cert.SetPrivateKey(privKey)
if (success == false)
    print cert.lastErrorText() + "\n";
    exit
end

http = Chilkat::CkHttp.new()

success = http.SetSslClientCert(cert)
if (success == false)
    print http.lastErrorText() + "\n";
    exit
end

# 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(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`

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

sbStringToSign = Chilkat::CkStringBuilder.new()
sbStringToSign.Append("(request-target): ")
sbStringToSign.Append(httpMethod)
sbStringToSign.ToLowercase()
sbStringToSign.Append(" ")
sbStringToSign.AppendLine(reqPath,false)

sbStringToSign.Append("date: ")
sbStringToSign.AppendLine(dt.getAsRfc822(false),false)

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 == false)
    print signingPrivKey.lastErrorText() + "\n";
    exit
end

rsa = Chilkat::CkRsa.new()
success = rsa.ImportPrivateKeyObj(signingPrivKey)
if (success == false)
    print rsa.lastErrorText() + "\n";
    exit
end

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(false))
req.AddHeader("Digest",sbDigestHdrVal.getAsString())
req.AddHeader("Authorization",sbAuthHdrVal.getAsString())
# resp is a CkHttpResponse
resp = http.PostUrlEncoded("https://api.sandbox.ing.com/oauth2/token",req)
if (http.get_LastMethodSuccess() == false)
    print http.lastErrorText() + "\n";
    exit
end

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

json = Chilkat::CkJsonObject.new()
json.Load(resp.bodyStr())

json.put_EmitCompact(false)
print json.emit() + "\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
end

# 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")