Visual FoxPro

Create CMS Signed File (PDF) with Multiple Signing Certificates

See more Digital Signatures Examples

Demonstrates how to sign a file by adding multiple signatures (multiple certificates). This example signs a PDF file to produce an output file that is a CMS signature wrapping the original PDF. (Note: This is different than modifying a PDF by injecting a signature into the PDF file format.)

Note: This example requires Chilkat v9.5.0.83 or greater.

Visual FoxPro

LOCAL lnSuccess
LOCAL loCrypt
LOCAL loCert1
LOCAL loCert2
LOCAL lcInFile
LOCAL lcP7sFile
LOCAL lcExtractedToFilePath

lnSuccess = 0

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

loCrypt = CreateObject('Chilkat.Crypt2')

* ------------ This example requires Chilkat v9.5.0.83 or greater.

loCert1 = CreateObject('Chilkat.Cert')
lnSuccess = loCert1.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123")
IF (lnSuccess <> 1) THEN
    ? loCert1.LastErrorText
    RELEASE loCrypt
    RELEASE loCert1
    CANCEL
ENDIF

loCert2 = CreateObject('Chilkat.Cert')
lnSuccess = loCert2.LoadPfxFile("qa_data/pfx/test_secret.pfx","secret")
IF (lnSuccess <> 1) THEN
    ? loCert2.LastErrorText
    RELEASE loCrypt
    RELEASE loCert1
    RELEASE loCert2
    CANCEL
ENDIF

* ------------ This example requires Chilkat v9.5.0.83 or greater.

* Tell the crypt component to use both certificates for signing. 
* When we create the signature, it will be signed by both certificates.
lnSuccess = loCrypt.AddSigningCert(loCert1)
IF (lnSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert1
    RELEASE loCert2
    CANCEL
ENDIF

lnSuccess = loCrypt.AddSigningCert(loCert2)
IF (lnSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert1
    RELEASE loCert2
    CANCEL
ENDIF

* The CadesEnabled property applies to all methods that create PKCS7 signatures. 
* To create a CAdES-BES signature, set this property equal to true. 
loCrypt.CadesEnabled = 1

loCrypt.HashAlgorithm = "sha256"

* We can sign any type of file, creating a .p7s as output.
* The .p7s contains the signature and also embeds the data of the file that is signed.
lcInFile = "qa_data/pdf/sample.pdf"
lcP7sFile = "qa_output/sample.pdf.p7s"

* Create the CAdES-BES attached signature, which contains the original data.
* Note: Chilkat's function naming is not accurate.  CreateP7M creates a PKCS7 signature where the signed file
* is contained within the signature.  CreateP7S creates a detached PKCS7 signature where the signed file
* is NOT contained within the signature.  We want the data to be contained in the signature, therefore
* we call CreateP7M even though we are naming our output file .p7s.
lnSuccess = loCrypt.CreateP7M(lcInFile,lcP7sFile)
IF (lnSuccess = 0) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert1
    RELEASE loCert2
    CANCEL
ENDIF

* Verify the .p7s file and extract the original file from the .p7s. 
lcExtractedToFilePath = "qa_output/sample.pdf"
lnSuccess = loCrypt.VerifyP7M(lcP7sFile,lcExtractedToFilePath)
IF (lnSuccess = 0) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert1
    RELEASE loCert2
    CANCEL
ENDIF

? "Success!"

RELEASE loCrypt
RELEASE loCert1
RELEASE loCert2