Visual FoxPro

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). Visual FoxPro

LOCAL lnSuccess
LOCAL loPdf
LOCAL loJson
LOCAL loCert

lnSuccess = 0

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

loPdf = CreateObject('Chilkat.Pdf')

* Load a PDF to be signed.
* The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
lnSuccess = loPdf.LoadFile("qa_data/pdf/hello.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    CANCEL
ENDIF

* Options for signing are specified in JSON.
loJson = CreateObject('Chilkat.JsonObject')

* In most cases, the signingCertificateV2 and signingTime attributes are required.
loJson.UpdateInt("signingCertificateV2",1)
loJson.UpdateInt("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".
loJson.UpdateBool("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
loJson.UpdateBool("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.
loJson.UpdateString("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.
loJson.UpdateString("timestampToken.tsaUsername","the_tsa_username")
loJson.UpdateString("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.)
loJson.UpdateBool("timestampToken.requestTsaCert",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 with a TSA timestamp.")

* Load the signing certificate. (Use your own certificate.)
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","pfxPassword")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    CANCEL
ENDIF

* Tell the pdf object to use the certificate for signing.
lnSuccess = loPdf.SetSigningCert(loCert)
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    CANCEL
ENDIF

lnSuccess = loPdf.SignPdf(loJson,"qa_output/hello_ltv_signed_with_timestamp.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    CANCEL
ENDIF

? "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)

RELEASE loPdf
RELEASE loJson
RELEASE loCert