SSH Authenticate using a Smart Card Private Key

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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.

local chilkat = require("chilkat")

-- 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.

local pkcs11 = chilkat.Pkcs11.new()

-- Use the PKCS#11 driver (.dll, .so, or .dylib) for your particular HSM.
pkcs11.shared_lib_path = "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.
local pin = "0000"

-- Normal user = 1
local userType = 1

local success = pkcs11:quick_session(userType, pin)
if not success then
    print(pkcs11.last_error_text)
    return
end

-- 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
local jsonTemplate = chilkat.JsonObject.new()
jsonTemplate:update_string("class", "private_key")
jsonTemplate:update_string("key_type", "rsa")
jsonTemplate:update_string("label", "MySshKey")

local privKeyHandle = pkcs11:find_object(jsonTemplate)
if privKeyHandle == 0 then
    print(pkcs11.last_error_text)
    return
end

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

-- Find the corresponding public key by changing the class in the same template.
jsonTemplate:update_string("class", "public_key")

local pubKeyHandle = pkcs11:find_object(jsonTemplate)
if pubKeyHandle == 0 then
    print(pkcs11.last_error_text)
    return
end

print("public key handle: " .. pubKeyHandle)

-- Create an empty SSH key object and tell it to use the PKCS#11 handles, indicating the key type.
local sshKey = chilkat.SshKey.new()
success = sshKey:use_pkcs11(pkcs11, privKeyHandle, pubKeyHandle, "rsa")
if not success then
    print(sshKey.last_error_text)
    return
end

local ssh = chilkat.Ssh.new()

local port = 22
success = ssh:connect("ssh.example.com", port)
if not success then
    print(ssh.last_error_text)
    return
end

-- Authentication uses the existing PKCS#11 session.  The signing happens on the smart card --
-- the private key never leaves the device.
success = ssh:authenticate_pk("mySshLogin", sshKey)
if not success then
    print(ssh.last_error_text)
    return
end

print("Public-key authentication successful.")

-- ... use the authenticated SSH session ...

ssh:disconnect()

pkcs11:logout()
pkcs11:close_session()