Go

Verify Opaque Signature and Retrieve Signing Certificates

See more Digital Signatures Examples

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign. Go

    success := false

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

    crypt := chilkat.NewCrypt2()

    // Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
    success = crypt.VerifyP7M("qa_data/p7m/opaqueSig.p7","qa_output/originalData.dat")
    if success == false {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        return
    }

    // Alternatively, we can do it in memory...
    binData := chilkat.NewBinData()
    success = binData.LoadFile("qa_data/p7m/opaqueSig.p7")
    // Your app should check for success, but we'll skip the check for brevity..

    // If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
    success = crypt.OpaqueVerifyBd(binData)
    if success == false {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        binData.DisposeBinData()
        return
    }

    // For our testing, we signed some text, so we can get it from the binData..
    fmt.Println("Original Data:")
    fmt.Println(*binData.GetString("utf-8"))

    // After any method call that verifies a signature, the crypt object will contain the certificate(s)
    // that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

    // Get each signing certificate, and build the certificate chain for each.
    cert := chilkat.NewCert()
    certChain := chilkat.NewCertChain()
    numCerts := crypt.NumSignerCerts()
    i := 0
    for i < numCerts {
        crypt.LastSignerCert(i,cert)
        fmt.Println(cert.SubjectDN())

        success = cert.BuildCertChain(certChain)
        if success == false {
            fmt.Println(cert.LastErrorText())
            crypt.DisposeCrypt2()
            binData.DisposeBinData()
            cert.DisposeCert()
            certChain.DisposeCertChain()
            return
        }

        i = i + 1
    }


    crypt.DisposeCrypt2()
    binData.DisposeBinData()
    cert.DisposeCert()
    certChain.DisposeCertChain()