Go

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.

Go

    success := false

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

    crypt := chilkat.NewCrypt2()

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

    cert1 := chilkat.NewCert()
    success = cert1.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123")
    if success != true {
        fmt.Println(cert1.LastErrorText())
        crypt.DisposeCrypt2()
        cert1.DisposeCert()
        return
    }

    cert2 := chilkat.NewCert()
    success = cert2.LoadPfxFile("qa_data/pfx/test_secret.pfx","secret")
    if success != true {
        fmt.Println(cert2.LastErrorText())
        crypt.DisposeCrypt2()
        cert1.DisposeCert()
        cert2.DisposeCert()
        return
    }

    // ------------ 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 = crypt.AddSigningCert(cert1)
    if success != true {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        cert1.DisposeCert()
        cert2.DisposeCert()
        return
    }

    success = crypt.AddSigningCert(cert2)
    if success != true {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        cert1.DisposeCert()
        cert2.DisposeCert()
        return
    }

    // The CadesEnabled property applies to all methods that create PKCS7 signatures. 
    // To create a CAdES-BES signature, set this property equal to true. 
    crypt.SetCadesEnabled(true)

    crypt.SetHashAlgorithm("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 := "qa_data/pdf/sample.pdf"
    p7sFile := "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 = crypt.CreateP7M(inFile,p7sFile)
    if success == false {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        cert1.DisposeCert()
        cert2.DisposeCert()
        return
    }

    // Verify the .p7s file and extract the original file from the .p7s. 
    extractedToFilePath := "qa_output/sample.pdf"
    success = crypt.VerifyP7M(p7sFile,extractedToFilePath)
    if success == false {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        cert1.DisposeCert()
        cert2.DisposeCert()
        return
    }

    fmt.Println("Success!")

    crypt.DisposeCrypt2()
    cert1.DisposeCert()
    cert2.DisposeCert()