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.

load ./chilkat.dll

set success 0

#  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.

set pkcs11 [new_CkPkcs11]

#  Use the PKCS#11 driver (.dll, .so, or .dylib) for your particular HSM.
CkPkcs11_put_SharedLibPath $pkcs11 "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.
set pin "0000"

#  Normal user = 1
set userType 1

set success [CkPkcs11_QuickSession $pkcs11 $userType $pin]
if {$success == 0} then {
    puts [CkPkcs11_lastErrorText $pkcs11]
    delete_CkPkcs11 $pkcs11
    exit
}

#  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
set jsonTemplate [new_CkJsonObject]

CkJsonObject_UpdateString $jsonTemplate "class" "private_key"
CkJsonObject_UpdateString $jsonTemplate "key_type" "rsa"
CkJsonObject_UpdateString $jsonTemplate "label" "MySshKey"

set privKeyHandle [CkPkcs11_FindObject $pkcs11 $jsonTemplate]
if {$privKeyHandle == 0} then {
    puts [CkPkcs11_lastErrorText $pkcs11]
    delete_CkPkcs11 $pkcs11
    delete_CkJsonObject $jsonTemplate
    exit
}

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

#  Find the corresponding public key by changing the class in the same template.
CkJsonObject_UpdateString $jsonTemplate "class" "public_key"

set pubKeyHandle [CkPkcs11_FindObject $pkcs11 $jsonTemplate]
if {$pubKeyHandle == 0} then {
    puts [CkPkcs11_lastErrorText $pkcs11]
    delete_CkPkcs11 $pkcs11
    delete_CkJsonObject $jsonTemplate
    exit
}

puts "public key handle: $pubKeyHandle"

#  Create an empty SSH key object and tell it to use the PKCS#11 handles, indicating the key type.
set sshKey [new_CkSshKey]

set success [CkSshKey_UsePkcs11 $sshKey $pkcs11 $privKeyHandle $pubKeyHandle "rsa"]
if {$success == 0} then {
    puts [CkSshKey_lastErrorText $sshKey]
    delete_CkPkcs11 $pkcs11
    delete_CkJsonObject $jsonTemplate
    delete_CkSshKey $sshKey
    exit
}

set ssh [new_CkSsh]

set port 22
set success [CkSsh_Connect $ssh "ssh.example.com" $port]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkPkcs11 $pkcs11
    delete_CkJsonObject $jsonTemplate
    delete_CkSshKey $sshKey
    delete_CkSsh $ssh
    exit
}

#  Authentication uses the existing PKCS#11 session.  The signing happens on the smart card --
#  the private key never leaves the device.
set success [CkSsh_AuthenticatePk $ssh "mySshLogin" $sshKey]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkPkcs11 $pkcs11
    delete_CkJsonObject $jsonTemplate
    delete_CkSshKey $sshKey
    delete_CkSsh $ssh
    exit
}

puts "Public-key authentication successful."

#  ... use the authenticated SSH session ...

CkSsh_Disconnect $ssh

CkPkcs11_Logout $pkcs11
CkPkcs11_CloseSession $pkcs11

delete_CkPkcs11 $pkcs11
delete_CkJsonObject $jsonTemplate
delete_CkSshKey $sshKey
delete_CkSsh $ssh