(Visual FoxPro) Sign PDF in the Cloud using AWS KMS

See more Signing in the Cloud Examples

Demonstrates how to sign a PDF using the AWS Key Management Service. The signing of the hash happens in the Cloud on AWS KMS. Everything else involving the updating the PDF to add the signature happens locally within Chilkat.

Note: This example requires Chilkat v9.5.0.96 or greater.

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ActiveX for 32-bit and 64-bit Windows

LOCAL loPdf
LOCAL lnSuccess
LOCAL loJson
LOCAL loCert
LOCAL loJsonAwsKms

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Pdf')
loPdf = CreateObject('Chilkat.Pdf')

* Load a PDF to be signed.
lnSuccess = loPdf.LoadFile("qa_data/pdf/helloWorld.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    CANCEL
ENDIF

* Options for signing are specified in JSON.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')

* Optionally create an LTV-enabled signature
loJson.UpdateBool("ltvOcsp",1)

* Define the appearance of the signature.
loJson.UpdateInt("page",1)
loJson.UpdateString("appearance.y","top")
loJson.UpdateString("appearance.x","left")
loJson.UpdateString("appearance.fontScale","10.0")
loJson.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
loJson.UpdateString("appearance.text[1]","current_dt")
loJson.UpdateString("appearance.text[2]","This is an LTV-enabled signature.")

* Load the certificate used for signing.  The certificate's private key is stored in AWS KMS
* However, we still need the certificate locally (without private key).
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadFromFile("qa_data/certs/myCert.cer")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    CANCEL
ENDIF

* Here's a screenshot of our private key AWS KMS:


* To sign using AWS KMS, 
* add the following lines of code to specify your AWS authentication credentials,
* and the ID of the KMS private key.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJsonAwsKms = CreateObject('Chilkat.JsonObject')
* Set the "service" equal to "aws_kms" to tell Chilkat to use AWS KMS for signing.
loJsonAwsKms.UpdateString("service","aws_kms")
loJsonAwsKms.UpdateString("access_key","ACCESS_KEY")
loJsonAwsKms.UpdateString("secret_key","SECRET_KEY")
* Make sure to specify the correct region for your case.
loJsonAwsKms.UpdateString("region","us-west-2")
* In the above screenshot, our key ID is "187012e8-008f-4fc7-b100-5efe6146dff2".  You will use your key ID.
loJsonAwsKms.UpdateString("key_id","187012e8-008f-4fc7-b100-5efe6146dff2")

lnSuccess = loCert.SetCloudSigner(loJsonAwsKms)

* Tell the pdf object to use the certificate for signing (and for AWS KMS to do the actual signing of the hash).
lnSuccess = loPdf.SetSigningCert(loCert)
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    RELEASE loJsonAwsKms
    CANCEL
ENDIF

* Chilkat will build the signed PDF locally, but will (internally) use AWS KMS
* to do the RSA (or EC) sign hash operation.
lnSuccess = loPdf.SignPdf(loJson,"qa_output/hello_ltv_signed.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    RELEASE loJsonAwsKms
    CANCEL
ENDIF

? "PDF Cloud Signing using AWS KMS Successful."

RELEASE loPdf
RELEASE loJson
RELEASE loCert
RELEASE loJsonAwsKms