C++

SSH HSM Public Key Authentication

Demonstrates SSH public-key authentication using a private key stored on an HSM — a USB token or smart card — accessed through PKCS#11. A session is opened with the vendor's driver, the key handles are located, and an SshKey object is bound to them with UsePkcs11.

Background: The point of an HSM is that the private key is generated on the device and cannot be exported: the signing operation happens on the hardware, so the key material never reaches your application's memory or disk. Even a fully compromised host cannot yield a copy of the key. PKCS#11 is the vendor-neutral interface to such devices, which is why the driver path and the object-finding template are the only vendor-specific parts of this example.

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#include <CkPkcs11.h>
#include <CkJsonObject.h>
#include <CkSshKey.h>
#include <CkSsh.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    //  Demonstrates SSH public-key authentication using a private key stored on an HSM (a USB token
    //  or smart card) accessed through PKCS#11.
    //  
    //  Note: Chilkat's PKCS#11 implementation runs on Windows, Linux, macOS, and other supported
    //  operating systems.

    CkPkcs11 pkcs11;

    //  The PKCS#11 driver supplied by your HSM vendor: a .dll on Windows, a .so on Linux, or a
    //  .dylib on macOS.
    pkcs11.put_SharedLibPath("C:/Program Files (x86)/Gemalto/IDGo 800 PKCS#11/IDPrimePKCS1164.dll");

    //  The PIN should come from a secure source rather than being hard-coded.
    const char *pin = "0000";

    //  Normal user = 1
    int userType = 1;

    success = pkcs11.QuickSession(userType,pin);
    if (success == false) {
        std::cout << pkcs11.lastErrorText() << "\r\n";
        return;
    }

    //  Describe the private key object to be located on the HSM.
    CkJsonObject json;
    json.UpdateString("class","private_key");
    json.UpdateString("label","MySshKey");

    unsigned long priv_handle = pkcs11.FindObject(json);
    if (priv_handle == 0) {
        std::cout << pkcs11.lastErrorText() << "\r\n";
        return;
    }

    //  Find the corresponding public key by changing the class in the same template.
    json.UpdateString("class","public_key");

    unsigned long pub_handle = pkcs11.FindObject(json);
    if (pub_handle == 0) {
        std::cout << pkcs11.lastErrorText() << "\r\n";
        return;
    }

    //  Create an SSH key object that uses the HSM handles.  The key type may be "rsa" or "ec".
    CkSshKey key;
    const char *keyType = "rsa";
    success = key.UsePkcs11(pkcs11,priv_handle,pub_handle,keyType);
    if (success == false) {
        std::cout << key.lastErrorText() << "\r\n";
        return;
    }

    CkSsh ssh;

    int port = 22;
    success = ssh.Connect("ssh.example.com",port);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    //  The corresponding public key must already be installed on the SSH server for the account.
    //  The signing operation happens on the HSM -- the private key never leaves the device.
    success = ssh.AuthenticatePk("mySshLogin",key);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "Public-key authentication successful." << "\r\n";

    ssh.Disconnect();

    pkcs11.Logout();
    pkcs11.CloseSession();
    }