PureBasic

Sign PDF with Timestamp from TSA (Timestamp Server Authority)

See more PDF Signatures Examples

This example demonstrates how to a sign a PDF that is both long-term validation (LTV) enabled and includes a validating timestamp from a TSA (Timestamp Server Authority). PureBasic

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 a PDF to be signed.
    ; The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
    success = CkPdf::ckLoadFile(pdf,"qa_data/pdf/hello.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

    ; In most cases, the signingCertificateV2 and signingTime attributes are required.
    CkJsonObject::ckUpdateInt(json,"signingCertificateV2",1)
    CkJsonObject::ckUpdateInt(json,"signingTime",1)

    ; Tell Chilkat to create an LTV-enabled (long term validation) signature.
    ; See PDF Long-Term Validation (LTV) Signature Example for more detailed comments about "ltvOcsp".
    CkJsonObject::ckUpdateBool(json,"ltvOcsp",1)

    ; Tell Chilkat to request a timestamp from a TSA server and include the timestamp token (1.2.840.113549.1.9.16.2.14)
    ; in the CMS signature's authentication attributes
    CkJsonObject::ckUpdateBool(json,"timestampToken.enabled",1)

    ; In this example, we'll use a free TSA server (timestamp.digicert.com), but you may want to use your own timestamp authority server.
    CkJsonObject::ckUpdateString(json,"timestampToken.tsaUrl","http://timestamp.digicert.com")

    ; If the timestamp server requires a username/password, do the following.  Otherwise omit the following few lines of code.
    CkJsonObject::ckUpdateString(json,"timestampToken.tsaUsername","the_tsa_username")
    CkJsonObject::ckUpdateString(json,"timestampToken.tsaPassword","the_tsa_password")

    ; When requesting the timestamp token, ask the server to include its certificate in the timestamp token response.
    ; This allows for the timestamp server's certificate to be included in the LTV validation (i.e. if the timestamp server
    ; has an OCSP URL, then Chilkat will also do the OCSP request for the timestamp server's certificate.)
    CkJsonObject::ckUpdateBool(json,"timestampToken.requestTsaCert",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 with a TSA timestamp.")

    ; Load the signing certificate. (Use your own certificate.)
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadPfxFile(cert,"qa_data/pfx/myPdfSigningCert.pfx","pfxPassword")
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Tell the pdf object to use the certificate for signing.
    success = CkPdf::ckSetSigningCert(pdf,cert)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

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

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

    ; If you open the Signature Panel in Adobe Acrobat, it will indicate that the signature is LTV enabled
    ; and contains an embedded timestamp:
    ; (image:https://example-code.com/images/ltv_signature_with_timestamp.jpg/endImage)


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


    ProcedureReturn
EndProcedure