(PureBasic) Sign a File to Create a .p7m File (using a PFX)

PureBasic example to sign a file creating a .p7m file as output. The .p7m contains the signed contents of the original file. It can be verified and restored by calling VerifyP7M.

Note: This example requires Chilkat v10.1.2 or greater.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkCertStore.pb"
IncludeFile "CkCert.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkCrypt2.pb"

Procedure ChilkatExample()

    ; This example requires 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

    ; Use a digital certificate and private key from a PFX file (.pfx or .p12).
    signingCertSubject.s = "Acme Inc"
    pfxFilename.s = "/Users/chilkat/testData/pfx/acme.pfx"
    pfxPassword.s = "test123"

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

    success.i = CkCertStore::ckLoadPfxFile(certStore,pfxFilename,pfxPassword)
    If success <> 1
        Debug CkCertStore::ckLastErrorText(certStore)
        CkCrypt2::ckDispose(crypt)
        CkCertStore::ckDispose(certStore)
        ProcedureReturn
    EndIf

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

    CkJsonObject::ckUpdateString(jsonCN,"CN",signingCertSubject)

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

    success = CkCertStore::ckFindCert(certStore,jsonCN,cert)
    If success = 0
        Debug "Failed to find certificate by subject common name."
        CkCrypt2::ckDispose(crypt)
        CkCertStore::ckDispose(certStore)
        CkJsonObject::ckDispose(jsonCN)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Tell the crypt component to use this cert.
    success = CkCrypt2::ckSetSigningCert(crypt,cert)

    ; We can sign any type of file, creating a .p7m as output:
    inFile.s = "/Users/chilkat/testData/pdf/sample.pdf"
    outputFile.s = "/Users/chilkat/testData/p7m/sample.pdf.p7m"
    success = CkCrypt2::ckCreateP7M(crypt,inFile,outputFile)
    If success = 0
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCrypt2::ckDispose(crypt)
        CkCertStore::ckDispose(certStore)
        CkJsonObject::ckDispose(jsonCN)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Verify and restore the original file:
    success = CkCrypt2::ckSetVerifyCert(crypt,cert)

    inFile = outputFile
    outputFile = "/Users/chilkat/testData/pdf/restored.pdf"

    success = CkCrypt2::ckVerifyP7M(crypt,inFile,outputFile)
    If success = 0
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCrypt2::ckDispose(crypt)
        CkCertStore::ckDispose(certStore)
        CkJsonObject::ckDispose(jsonCN)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    Debug "Success!"


    CkCrypt2::ckDispose(crypt)
    CkCertStore::ckDispose(certStore)
    CkJsonObject::ckDispose(jsonCN)
    CkCert::ckDispose(cert)


    ProcedureReturn
EndProcedure