(PureBasic) Sign PDF in the Cloud using AWS CloudHSM

See more Signing in the Cloud Examples

Demonstrates how to sign a PDF using AWS CloudHSM. The signing of the hash happens on a hardware token in AWS CloudHSM. 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 "CkPkcs11.pb"
IncludeFile "CkCert.pb"
IncludeFile "CkPdf.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

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

    ; Note: Chilkat's PKCS11 implementation runs on Windows, Linux, Mac OS X, and other supported operating systems.

    pkcs11.i = CkPkcs11::ckCreate()
    If pkcs11.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Provide the path to the AWS CloudHSM PKCS11 driver.
    ; This example runs on Windows, so we'll provide the CloudHSM DLL.
    ; If your code runs on Linux, the CloudHSM driver might be at /opt/cloudhsm/lib/libcloudhsm_pkcs11.so
    CkPkcs11::setCkSharedLibPath(pkcs11, "C:\Program Files\Amazon\CloudHSM\lib\cloudhsm_pkcs11.dll")

    ; Your PIN should be a string containing your crypto user's login and password, with a colon char delimiting.
    ; See https://docs.aws.amazon.com/cloudhsm/latest/userguide/pkcs11-pin.html
    pin.s = "user:password"
    userType.i = 1

    ; Establish a PKCS logged-on session using the driver (.so, .dylib, or .dll) as specified in the SharedLibPath above.
    success.i = CkPkcs11::ckQuickSession(pkcs11,userType,pin)
    If success = 0
        Debug CkPkcs11::ckLastErrorText(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        ProcedureReturn
    EndIf

    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)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Tell the certificate to link with the PKCS11 session.
    ; The cert's private key should be installed on the CloudHSM.
    ; If there are multiple private keys on the CloudHSM, then Chilkat will automatically
    ; locate and use the private key corresponding to the certificate.
    success = CkCert::ckLinkPkcs11(cert,pkcs11)
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; --------------------------------------------------------------------------
    ; At this point, we have the cert to be used for signing.
    ; Our PDF signing code is the same as for a cert obtained from any other source..

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

    ; Load a PDF to be signed.
    success = CkPdf::ckLoadFile(pdf,"qa_data/pdf/hello.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        success = CkPkcs11::ckCloseSession(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkPdf::ckDispose(pdf)
        ProcedureReturn
    EndIf

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

    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,"signingAlgorithm","pss")
    CkJsonObject::ckUpdateString(json,"hashAlgorithm","sha256")

    i.i = 0
    CkJsonObject::setCkI(json, i)
    CkJsonObject::ckUpdateString(json,"appearance.text[i]","Digitaly signed by: Xyz Widgets, Inc.")
    i = i + 1
    CkJsonObject::setCkI(json, i)
    CkJsonObject::ckUpdateString(json,"appearance.text[i]","current_dt")
    i = i + 1
    CkJsonObject::setCkI(json, i)
    CkJsonObject::ckUpdateString(json,"appearance.text[i]","blah blah blah")

    ; The certificate is internally linked to the Pkcs11 object, which is currently in an authenticated session.
    success = CkPdf::ckSetSigningCert(pdf,cert)

    success = CkPdf::ckSignPdf(pdf,json,"qa_output/out.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        success = CkPkcs11::ckCloseSession(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        ProcedureReturn
    EndIf

    ; --------------------------------------------------------------------------

    ; Revert to an unauthenticated session by calling Logout.
    success = CkPkcs11::ckLogout(pkcs11)
    If success = 0
        Debug CkPkcs11::ckLastErrorText(pkcs11)
        success = CkPkcs11::ckCloseSession(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        ProcedureReturn
    EndIf

    ; When finished, close the session.
    ; It is important to close the session (memory leaks will occur if the session is not properly closed).
    success = CkPkcs11::ckCloseSession(pkcs11)
    If success = 0
        Debug CkPkcs11::ckLastErrorText(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        ProcedureReturn
    EndIf

    Debug "Success."


    CkPkcs11::ckDispose(pkcs11)
    CkCert::ckDispose(cert)
    CkPdf::ckDispose(pdf)
    CkJsonObject::ckDispose(json)


    ProcedureReturn
EndProcedure