Xojo Plugin

SSH Authenticate using a Smart Card Private Key

Demonstrates using a private key stored on an HSM (smart card or token) for SSH public-key authentication. A JSON template locates the private and public key objects by class, key type, and label, and the returned handles are bound to an SshKey object.

Background: PKCS#11 objects are found by attribute rather than by name alone, which is why a template describing the class, key type, and label is used. An important practical detail is that the returned handles are valid only for the lifetime of the PKCS#11 session — they cannot be cached and reused later, so a subsequent session must locate the objects again. Logging out and closing the session when finished releases the device for other applications.

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Dim success As Boolean
success = False

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

//  Demonstrates using a private key stored on an HSM (smart card or token) for SSH public-key
//  authentication.  Public-key authentication means the client uses the private key, while the
//  corresponding public key is installed on the server under the SSH account.
//  
//  Note: Chilkat's PKCS#11 implementation runs on Windows, Linux, macOS, and other supported
//  operating systems.

Dim pkcs11 As New Chilkat.Pkcs11

//  Use the PKCS#11 driver (.dll, .so, or .dylib) for your particular HSM.
pkcs11.SharedLibPath = "C:/Program Files (x86)/Gemalto/IDGo 800 PKCS#11/IDPrimePKCS11.dll"

//  The HSM PIN should come from a secure source rather than being hard-coded.
Dim pin As String
pin = "0000"

//  Normal user = 1
Dim userType As Int32
userType = 1

success = pkcs11.QuickSession(userType,pin)
If (success = False) Then
    System.DebugLog(pkcs11.LastErrorText)
    Return
End If

//  Provide a template describing the PKCS#11 object to find: an RSA private key labeled
//  "MySshKey".  For how such a key is originally imported, see
//  PKCS11 Import SSH Key
Dim jsonTemplate As New Chilkat.JsonObject
success = jsonTemplate.UpdateString("class","private_key")
success = jsonTemplate.UpdateString("key_type","rsa")
success = jsonTemplate.UpdateString("label","MySshKey")

Dim privKeyHandle As UInt32
privKeyHandle = pkcs11.FindObject(jsonTemplate)
If (privKeyHandle = 0) Then
    System.DebugLog(pkcs11.LastErrorText)
    Return
End If

//  The handle is only valid for the duration of this PKCS#11 session.  To use the key in a
//  later session, find it again.
System.DebugLog("private key handle: " + Str(privKeyHandle))

//  Find the corresponding public key by changing the class in the same template.
success = jsonTemplate.UpdateString("class","public_key")

Dim pubKeyHandle As UInt32
pubKeyHandle = pkcs11.FindObject(jsonTemplate)
If (pubKeyHandle = 0) Then
    System.DebugLog(pkcs11.LastErrorText)
    Return
End If

System.DebugLog("public key handle: " + Str(pubKeyHandle))

//  Create an empty SSH key object and tell it to use the PKCS#11 handles, indicating the key type.
Dim sshKey As New Chilkat.SshKey
success = sshKey.UsePkcs11(pkcs11,privKeyHandle,pubKeyHandle,"rsa")
If (success = False) Then
    System.DebugLog(sshKey.LastErrorText)
    Return
End If

Dim ssh As New Chilkat.Ssh

Dim port As Int32
port = 22
success = ssh.Connect("ssh.example.com",port)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

//  Authentication uses the existing PKCS#11 session.  The signing happens on the smart card --
//  the private key never leaves the device.
success = ssh.AuthenticatePk("mySshLogin",sshKey)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

System.DebugLog("Public-key authentication successful.")

//  ... use the authenticated SSH session ...

ssh.Disconnect 

success = pkcs11.Logout()
success = pkcs11.CloseSession()