B4X

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.

Chilkat B4X Downloads

Download Chilkat for B4X

B4X

Dim success As Boolean = 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.

Dim pkcs11 As ChilkatPkcs11
pkcs11.Initialize

'  The PKCS#11 driver supplied by your HSM vendor: a .dll on Windows, a .so on Linux, or a
'  .dylib on macOS.
pkcs11.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.
Dim pin As String = "0000"

'  Normal user = 1
Dim userType As Int = 1

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


'  Describe the private key object to be located on the HSM.
Dim json As ChilkatJsonObject
json.Initialize
json.UpdateString("class", "private_key")
json.UpdateString("label", "MySshKey")

Dim priv_handle As Long = pkcs11.FindObject(json)
If priv_handle = 0 Then
    Log(pkcs11.LastErrorText)
    Return
End If


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

Dim pub_handle As Long = pkcs11.FindObject(json)
If pub_handle = 0 Then
    Log(pkcs11.LastErrorText)
    Return
End If


'  Create an SSH key object that uses the HSM handles.  The key type may be "rsa" or "ec".
Dim key As ChilkatSshKey
key.Initialize
Dim keyType As String = "rsa"
success = key.UsePkcs11(pkcs11, priv_handle, pub_handle, keyType)
If success = False Then
    Log(key.LastErrorText)
    Return
End If


Dim ssh As ChilkatSsh
ssh.Initialize("ssh")

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


'  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 Then
    Log(ssh.LastErrorText)
    Return
End If


Log("Public-key authentication successful.")

ssh.Disconnect

pkcs11.Logout
pkcs11.CloseSession