(C++) Trust Specific Root CA Certificates

Demonstrates how to trust specific root CA certificates and none others.

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#include <CkTrustedRoots.h>
#include <CkCert.h>
#include <CkHttp.h>

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

    // This example will trust the Amazon root CA certificates provided at 
    // https://www.amazontrust.com/repository/

    // I've previously downloaded the root CA certificates to DER format.
    // Add each to the Chilkat TrustedRoots singleton object.

    CkTrustedRoots tRoots;

    CkCert caCert;
    bool success = caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA1.cer");
    if (success == false) {
        std::cout << caCert.lastErrorText() << "\r\n";
        return;
    }

    success = tRoots.AddCert(caCert);

    // Continue with the others.
    // For brevity, we're not checking return values for success/failure.
    success = caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA2.cer");
    success = tRoots.AddCert(caCert);

    success = caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA3.cer");
    success = tRoots.AddCert(caCert);

    success = caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA4.cer");
    success = tRoots.AddCert(caCert);

    success = caCert.LoadFromFile("qa_data/certs/aws_root_ca/SFSRootCAG2.cer");
    success = tRoots.AddCert(caCert);

    // Indicate we don't want to automatically trust the operating system's installed root CA certificates.
    // On a Windows operating system, this would be the registry-based CA certificate stores. 
    // On a Linux system, this could be /etc/ssl/certs/ca-certificates.crt, if it exists.
    tRoots.put_TrustSystemCaRoots(false);

    // Activate the trusted roots object.
    // Once activated, all Chilkat objects that use TLS connections (HTTP, REST, Socket, MailMan, IMAP, FTP, etc.)
    // will fail the TLS handshake if the server certificate is not verified and rooted with one of our explicitly trusted root certificates.
    success = tRoots.Activate();

    CkHttp http;

    // Note: We also need to explicitly indicate that server certificates are to be verified.
    http.put_RequireSslCertVerify(true);

    // For example, the following should fail because www.chilkatsoft.com's server certificate is not rooted in one of the explicitly trusted root CA certs.
    success = http.Download("https://www.chilkatsoft.com/helloWorld.txt","qa_output/helloWorld.txt");
    if (success != true) {
        // The above Download should fail.
        std::cout << http.lastErrorText() << "\r\n";

        // There should be a message in the LastErrorText indicating that we were "Unable to build certificate chain to root.."
    }

    // However, we should be able to make TLS connections to good.sca1a.amazontrust.com
    success = http.Download("https://good.sca1a.amazontrust.com/","qa_output/valid.html");
    if (success != true) {
        std::cout << http.lastErrorText() << "\r\n";
        return;
    }

    // We can still examine the LastErrorText and we'll find this message within:  
    // "The public key was successfully validated against the public key of the explicitly trusted root cert."
    std::cout << http.lastErrorText() << "\r\n";

    std::cout << "Success!" << "\r\n";
    }