(PureBasic) Sign PDF using ARSS (Aruba Remote Signing Service)

See more Signing in the Cloud Examples

Demonstrates how to digitally sign a PDF using the Aruba Remote Signing Service (ARSS). The example loads a local PDF and certificate, configures the ARSS cloud signer credentials, specifies the OTP authentication type with typeOtpAuth, and creates an LTV-enabled signed PDF where the private key remains protected on the Aruba signing server.

Note: This example requires Chilkat v11.5.0 or greater.

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

Procedure ChilkatExample()

    success.i = 0

    ; 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 the PDF that will be digitally signed.
    success = CkPdf::ckLoadFile(pdf,"qa_data/pdf/hello.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        ProcedureReturn
    EndIf

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

    ; Enable LTV (Long-Term Validation).
    ; When ltvOcsp is true, OCSP validation information is embedded in the PDF
    ; so that signature validation can continue to succeed in the future,
    ; even if the original OCSP responder is no longer available.
    CkJsonObject::ckUpdateBool(json,"ltvOcsp",1)

    ; Specify the visual appearance of the signature on the PDF page.
    CkJsonObject::ckUpdateInt(json,"page",1)
    CkJsonObject::ckUpdateString(json,"appearance.y","top")
    CkJsonObject::ckUpdateString(json,"appearance.x","left")
    CkJsonObject::ckUpdateString(json,"appearance.fontScale","10.0")

    ; Text lines displayed in the visible signature appearance.
    ; Special values such as "cert_cn" and "current_dt" are replaced
    ; with the certificate common name and current date/time.
    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 signing certificate.
    ; 
    ; The private key is NOT stored locally.  Instead, the private key is
    ; stored and protected on the Aruba Remote Signing Service (ARSS).
    ; 
    ; Even though the signing operation will occur remotely, Chilkat still
    ; needs the corresponding public certificate locally so that it can
    ; construct the CMS/PAdES signature and embed the certificate chain
    ; in the signed PDF.
    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

    ; Configure Aruba Remote Signing Service (ARSS) credentials.
    ; 
    ; When SetCloudSigner is called, Chilkat is instructed to perform
    ; cryptographic signing operations through the ARSS web service.
    ; The PDF is assembled locally, but the actual RSA signature operation
    ; is performed remotely using the private key held by Aruba.
    jsonArss.i = CkJsonObject::ckCreate()
    If jsonArss.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Required.  Indicates that the cloud signing provider is ARSS.
    CkJsonObject::ckUpdateString(jsonArss,"service","ARSS")

    ; The ARSS certificate identifier (for example, "AS0").
    ; This identifies which remote certificate/private key pair should be used.
    ; The remote certificate should correspond to the certificate loaded above.
    CkJsonObject::ckUpdateString(jsonArss,"certID","YOUR_ARSS_CERT_ID")

    ; OTP password associated with the Aruba remote-signing account.
    ; Depending on the ARSS configuration, an OTP may be required to
    ; authorize each signing operation.
    CkJsonObject::ckUpdateString(jsonArss,"otpPwd","YOUR_OTP_PWD")

    ; Specifies the OTP authentication environment.
    ; 
    ; Common values are:
    ;   "demoprod" - Demo/Test environment
    ;   "prod"     - Production environment
    ; 
    ; This value is sent to the ARSS service and determines how the OTP
    ; authentication is validated.  The correct value depends on the type
    ; of Aruba account and environment that has been provisioned.
    ; 
    ; If signing fails with an authentication-related error, verify that
    ; the typeOtpAuth value matches the environment associated with the
    ; ARSS account credentials being used.
    CkJsonObject::ckUpdateString(jsonArss,"typeOtpAuth","demoprod")

    ; ARSS account username.
    CkJsonObject::ckUpdateString(jsonArss,"user","YOUR_ARSS_USERNAME")

    ; ARSS account password.
    CkJsonObject::ckUpdateString(jsonArss,"userPWD","YOUR_ARSS_PASSWORD")

    ; Beginning with Chilkat v11.5.0, the ARSS endpoint can be explicitly
    ; specified.  This allows the application to target a particular
    ; Aruba signing service endpoint when required.
    CkJsonObject::ckUpdateString(jsonArss,"endpoint","https://app1.firma-remota.it/ArubaSignerService/webresources/signerservice")

    success = CkCert::ckSetCloudSigner(cert,jsonArss)
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkCert::ckDispose(cert)
        CkJsonObject::ckDispose(jsonArss)
        ProcedureReturn
    EndIf

    ; Associate the certificate with the PDF object.
    ; All subsequent signing operations will use this certificate.
    success = CkPdf::ckSetSigningCert(pdf,cert)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkCert::ckDispose(cert)
        CkJsonObject::ckDispose(jsonArss)
        ProcedureReturn
    EndIf

    ; Create the signed PDF.
    ; 
    ; Chilkat performs all PDF processing locally.  When the time comes
    ; to generate the cryptographic signature value, Chilkat sends the
    ; hash to ARSS, which signs it using the remote private key and returns
    ; the signature.  The private key never leaves the Aruba service.
    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(jsonArss)
        ProcedureReturn
    EndIf

    Debug "The PDF has been successfully cryptographically signed with long-term validation."


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


    ProcedureReturn
EndProcedure