(PureBasic) Create CMS Signed File (PDF) with Multiple Signing Certificates

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.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkCrypt2.pb"
IncludeFile "CkCert.pb"

Procedure ChilkatExample()

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

    crypt.i = CkCrypt2::ckCreate()
    If crypt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

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

    cert1.i = CkCert::ckCreate()
    If cert1.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkCert::ckLoadPfxFile(cert1,"qa_data/pfx/cert_test123.pfx","test123")
    If success <> 1
        Debug CkCert::ckLastErrorText(cert1)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert1)
        ProcedureReturn
    EndIf

    cert2.i = CkCert::ckCreate()
    If cert2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadPfxFile(cert2,"qa_data/pfx/test_secret.pfx","secret")
    If success <> 1
        Debug CkCert::ckLastErrorText(cert2)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    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.
    success = CkCrypt2::ckAddSigningCert(crypt,cert1)
    If success <> 1
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    success = CkCrypt2::ckAddSigningCert(crypt,cert2)
    If success <> 1
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    ; The CadesEnabled property applies to all methods that create PKCS7 signatures. 
    ; To create a CAdES-BES signature, set this property equal to true. 
    CkCrypt2::setCkCadesEnabled(crypt, 1)

    CkCrypt2::setCkHashAlgorithm(crypt, "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.
    inFile.s = "qa_data/pdf/sample.pdf"
    p7sFile.s = "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.
    success = CkCrypt2::ckCreateP7M(crypt,inFile,p7sFile)
    If success = 0
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    ; Verify the .p7s file and extract the original file from the .p7s. 
    extractedToFilePath.s = "qa_output/sample.pdf"
    success = CkCrypt2::ckVerifyP7M(crypt,p7sFile,extractedToFilePath)
    If success = 0
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    Debug "Success!"


    CkCrypt2::ckDispose(crypt)
    CkCert::ckDispose(cert1)
    CkCert::ckDispose(cert2)


    ProcedureReturn
EndProcedure