(PureBasic) Sign PDF in the Cloud using Azure Key Vault

See more Signing in the Cloud Examples

Demonstrates how to sign a PDF using Azure Key Vault. The signing of the hash happens in the Cloud on Azure Key Vault. 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.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkCert.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkPdf.pb"

Procedure ChilkatExample()

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

    pdf.i = CkPdf::ckCreate()
    If pdf.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Load a PDF to be signed.
    success.i = CkPdf::ckLoadFile(pdf,"qa_data/pdf/helloWorld.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        ProcedureReturn
    EndIf

    ; Options for signing are specified in JSON.
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Optionally create an LTV-enabled signature
    CkJsonObject::ckUpdateBool(json,"ltvOcsp",1)

    ; Define the appearance of the signature.
    CkJsonObject::ckUpdateInt(json,"page",1)
    CkJsonObject::ckUpdateString(json,"appearance.y","top")
    CkJsonObject::ckUpdateString(json,"appearance.x","left")
    CkJsonObject::ckUpdateString(json,"appearance.fontScale","10.0")
    CkJsonObject::ckUpdateString(json,"appearance.text[0]","Digitally signed by: cert_cn")
    CkJsonObject::ckUpdateString(json,"appearance.text[1]","current_dt")
    CkJsonObject::ckUpdateString(json,"appearance.text[2]","This is an LTV-enabled signature.")

    ; Load the certificate used for signing.  The certificate's private key is stored in 
    ; the Azure Key Vault.
    ; However, we still need the certificate locally (without private key).
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadFromFile(cert,"qa_data/certs/myCert.cer")
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Here's a screenshot of our certificate with private key on Azure Key Vault:
    

    ; To sign using the Azure Key Vault, 
    ; add the following lines of code to specify your authentication credentials,
    ; and the name of the certificate w/ private key on the Azure server to be used.
    jsonAzure.i = CkJsonObject::ckCreate()
    If jsonAzure.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Set the "service" equal to "azure_keyvault" to tell Chilkat to use Azure Key Vault for signing.
    CkJsonObject::ckUpdateString(jsonAzure,"service","azure_keyvault")
    CkJsonObject::ckUpdateString(jsonAzure,"client_id","APP_ID")
    CkJsonObject::ckUpdateString(jsonAzure,"client_secret","APP_PASSWORD")
    CkJsonObject::ckUpdateString(jsonAzure,"tenant_id","TENANT_ID")
    ; In the above screenshot, our vault name is "kvchilkat".  You will use your vault name.
    CkJsonObject::ckUpdateString(jsonAzure,"vault_name","VAULT_NAME")
    ; In the above screenshot, our cert name is "ChilkatTest1".  You will use your cert name.
    CkJsonObject::ckUpdateString(jsonAzure,"cert_name","CERT_NAME")
    ; In the above screenshot, our cert version is "63b94a23389546ecbc8eb6208a1bef37".  You will use your cert version.
    CkJsonObject::ckUpdateString(jsonAzure,"cert_version","CERT_VERSION")
    success = CkCert::ckSetCloudSigner(cert,jsonAzure)

    ; Tell the pdf object to use the certificate for signing (and for Azure Key Vault to do the actual signing of the hash).
    success = CkPdf::ckSetSigningCert(pdf,cert)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkCert::ckDispose(cert)
        CkJsonObject::ckDispose(jsonAzure)
        ProcedureReturn
    EndIf

    ; Chilkat will build the signed PDF locally, but will (internally) use Azure Key Vault
    ; to do the RSA (or EC) sign hash operation.
    success = CkPdf::ckSignPdf(pdf,json,"qa_output/hello_ltv_signed.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkCert::ckDispose(cert)
        CkJsonObject::ckDispose(jsonAzure)
        ProcedureReturn
    EndIf

    Debug "PDF Cloud Signing using Azure Key Vault Successful."


    CkPdf::ckDispose(pdf)
    CkJsonObject::ckDispose(json)
    CkCert::ckDispose(cert)
    CkJsonObject::ckDispose(jsonAzure)


    ProcedureReturn
EndProcedure