(Go) PKCS11 Find Certificate with Key Usage on Smart Card or USB Token

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Demonstrates how to find and return the 1st certificate on a smart card or USB token with a desired intended key usage.

Note: This example requires Chilkat v9.5.0.91 or later.

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

    // Note: Chilkat's PKCS11 implementation runs on Windows, Linux, Mac OS X, and other supported operating systems.

    pkcs11 := chilkat.NewPkcs11()

    pkcs11.SetSharedLibPath("aetpkss1.dll")

    success := pkcs11.Initialize()
    if success == false {
        fmt.Println(pkcs11.LastErrorText())
        pkcs11.DisposePkcs11()
        return
    }

    // Pass -1 for the slotID to open a session on the first non-empty slot.
    slotID := -1

    // Open a session.
    readWrite := true
    success = pkcs11.OpenSession(slotID,readWrite)
    if success == false {
        fmt.Println(pkcs11.LastErrorText())
        pkcs11.DisposePkcs11()
        return
    }

    // Make it an authenticated session by calling Login.
    // 
    // If we don't authenticate, then we won't be able to see the private keys, and thus
    // we won't know which certificates have an associated private key stored on the smart card.

    // The smart card PIN is passed to the Login method.
    // userType 1 indicates a "Normal User".
    userType := 1
    pin := "0000"
    success = pkcs11.Login(userType,pin)
    if success == false {
        fmt.Println(pkcs11.LastErrorText())
        success = pkcs11.CloseSession()
        pkcs11.DisposePkcs11()
        return
    }

    // --------------------------------------------------------------------------

    cert := chilkat.NewCert()

    // Find a certificate with an intended key usage.
    // Possible key usages to find are:
    // 
    // DigitalSignature
    // NonRepudiation
    // KeyEncipherment
    // DataEncipherment
    // CertificateSigning
    // CrlSigning
    // 
    // To find a cert having any one of several usages, pass a comma-separated list of usages:
    success = pkcs11.FindCert("keyUsage","NonRepudiation,DigitalSignature",cert)
    if success == true {
        fmt.Println("Cert with private key: ", cert.SubjectCN())
    } else {
        fmt.Println("No certificates having the intended key usage were found.")
    }

    // --------------------------------------------------------------------------

    // Revert to an unauthenticated session by calling Logout.
    success = pkcs11.Logout()
    if success == false {
        fmt.Println(pkcs11.LastErrorText())
        success = pkcs11.CloseSession()
        pkcs11.DisposePkcs11()
        cert.DisposeCert()
        return
    }

    // When finished, close the session.
    // It is important to close the session (memory leaks will occur if the session is not properly closed).
    success = pkcs11.CloseSession()
    if success == false {
        fmt.Println(pkcs11.LastErrorText())
        pkcs11.DisposePkcs11()
        cert.DisposeCert()
        return
    }

    fmt.Println("Success.")

    pkcs11.DisposePkcs11()
    cert.DisposeCert()