(PureBasic) Sign a File to Create a .p7s (Detached Signature)

PureBasic example to create a detached signature file (.p7s) for any type file. The signature can be verified by calling VerifyP7S and passing the original filename and the .p7s filename.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkCertStore.pb"
IncludeFile "CkCert.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

    cert.i = CkCertStore::ckFindCertBySubjectCN(certStore,signingCertSubject)
    If CkCertStore::ckLastMethodSuccess(certStore) = 0
        Debug "Failed to find certificate by subject common name."
        CkCrypt2::ckDispose(crypt)
        CkCertStore::ckDispose(certStore)
        ProcedureReturn
    EndIf

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

    ; We can sign any type of file, creating a .p7s as output:
    inFile.s = "/Users/chilkat/testData/pdf/sample.pdf"
    sigFile.s = "/Users/chilkat/testData/p7s/sample.p7s"

    success = CkCrypt2::ckCreateP7S(crypt,inFile,sigFile)
    If success = 0
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCert::ckDispose(cert)

        CkCrypt2::ckDispose(crypt)
        CkCertStore::ckDispose(certStore)
        ProcedureReturn
    EndIf

    success = CkCrypt2::ckVerifyP7S(crypt,inFile,sigFile)
    If success = 0
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCert::ckDispose(cert)

        CkCrypt2::ckDispose(crypt)
        CkCertStore::ckDispose(certStore)
        ProcedureReturn
    EndIf

    CkCert::ckDispose(cert)

    Debug "Success!"


    CkCrypt2::ckDispose(crypt)
    CkCertStore::ckDispose(certStore)


    ProcedureReturn
EndProcedure