(Go) About RSA Public/Private Keys

This example provides some additional information for understanding public/private key pairs. In demonstrates how a private key is a superset of the public key. A public key contains the modulus and exponent. The matching private key also contains the modulus and exponent, but also contains the additional private key parts.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

    success := false

    cert := Cert_Ref.html">chilkat.NewCert()

    // Load a digital certificate.
    success = cert.LoadFromFile("digitalCert.cer")
    if success == false {
        fmt.Println(cert.LastErrorText())
        cert.DisposeCert()
        return
    }

    // A .cer file does not contain the private key.  It should contain
    // the public key...
    pubKey := PublicKey_Ref.html">chilkat.NewPublicKey()
    cert.GetPublicKey(pubKey)

    // Let's have a look at it (in XML format).
    fmt.Println("Public Key from Certificate:")
    fmt.Println(*pubKey.GetXml())

    // An RSA public key consists of a modulus and exponent.

    // An RSA private key includes both the modulus and exponent,
    // as well as other "big" numbers: P, Q, D, etc.

    // Let's load an RSA private key from a DER-encoded file:
    privKey := PrivateKey_Ref.html">chilkat.NewPrivateKey()

    success = privKey.LoadAnyFormatFile("PrivateKey_Ref.html">PrivateKey.key","")
    if success != true {
        fmt.Println(privKey.LastErrorText())
        cert.DisposeCert()
        pubKey.DisposePublicKey()
        privKey.DisposePrivateKey()
        return
    }

    // If this private key is the matching half to the public key from
    // the certificate, then the modulus and exponent should
    // be identical.  (Thus, a "private key" really contains both the public part as well as the private parts...).
    fmt.Println("Private Key from DER:")
    fmt.Println(*privKey.GetXml())

    cert.DisposeCert()
    pubKey.DisposePublicKey()
    privKey.DisposePrivateKey()