Visual FoxPro

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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LOCAL lnSuccess
LOCAL loPkcs11
LOCAL lcPin
LOCAL lnUserType
LOCAL loJson
LOCAL lnPriv_handle
LOCAL lnPub_handle
LOCAL loKey
LOCAL lcKeyType
LOCAL loSsh
LOCAL lnPort

lnSuccess = 0

*  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.

loPkcs11 = CreateObject('Chilkat.Pkcs11')

*  The PKCS#11 driver supplied by your HSM vendor: a .dll on Windows, a .so on Linux, or a
*  .dylib on macOS.
loPkcs11.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.
lcPin = "0000"

*  Normal user = 1
lnUserType = 1

lnSuccess = loPkcs11.QuickSession(lnUserType,lcPin)
IF (lnSuccess = 0) THEN
    ? loPkcs11.LastErrorText
    RELEASE loPkcs11
    CANCEL
ENDIF

*  Describe the private key object to be located on the HSM.
loJson = CreateObject('Chilkat.JsonObject')
loJson.UpdateString("class","private_key")
loJson.UpdateString("label","MySshKey")

lnPriv_handle = loPkcs11.FindObject(loJson)
IF (lnPriv_handle = 0) THEN
    ? loPkcs11.LastErrorText
    RELEASE loPkcs11
    RELEASE loJson
    CANCEL
ENDIF

*  Find the corresponding public key by changing the class in the same template.
loJson.UpdateString("class","public_key")

lnPub_handle = loPkcs11.FindObject(loJson)
IF (lnPub_handle = 0) THEN
    ? loPkcs11.LastErrorText
    RELEASE loPkcs11
    RELEASE loJson
    CANCEL
ENDIF

*  Create an SSH key object that uses the HSM handles.  The key type may be "rsa" or "ec".
loKey = CreateObject('Chilkat.SshKey')
lcKeyType = "rsa"
lnSuccess = loKey.UsePkcs11(loPkcs11,lnPriv_handle,lnPub_handle,lcKeyType)
IF (lnSuccess = 0) THEN
    ? loKey.LastErrorText
    RELEASE loPkcs11
    RELEASE loJson
    RELEASE loKey
    CANCEL
ENDIF

loSsh = CreateObject('Chilkat.Ssh')

lnPort = 22
lnSuccess = loSsh.Connect("ssh.example.com",lnPort)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loPkcs11
    RELEASE loJson
    RELEASE loKey
    RELEASE loSsh
    CANCEL
ENDIF

*  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.
lnSuccess = loSsh.AuthenticatePk("mySshLogin",loKey)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loPkcs11
    RELEASE loJson
    RELEASE loKey
    RELEASE loSsh
    CANCEL
ENDIF

? "Public-key authentication successful."

loSsh.Disconnect()

loPkcs11.Logout()
loPkcs11.CloseSession()

RELEASE loPkcs11
RELEASE loJson
RELEASE loKey
RELEASE loSsh