Perl

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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use strict;
use warnings;
use Chilkat2;

# 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.

my $pkcs11 = Chilkat2::Pkcs11->new;

# 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.
my $pin = '0000';

# Normal user = 1
my $userType = 1;

my $success = $pkcs11->QuickSession($userType, $pin);
if (!$success) {
    print $pkcs11->LastErrorText, "\n";
    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
my $jsonTemplate = Chilkat2::JsonObject->new;
$jsonTemplate->UpdateString('class', 'private_key');
$jsonTemplate->UpdateString('key_type', 'rsa');
$jsonTemplate->UpdateString('label', 'MySshKey');

my $privKeyHandle = $pkcs11->FindObject($jsonTemplate);
if ($privKeyHandle == 0) {
    print $pkcs11->LastErrorText, "\n";
    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.
print 'private key handle: ', $privKeyHandle, "\n";

# Find the corresponding public key by changing the class in the same template.
$jsonTemplate->UpdateString('class', 'public_key');

my $pubKeyHandle = $pkcs11->FindObject($jsonTemplate);
if ($pubKeyHandle == 0) {
    print $pkcs11->LastErrorText, "\n";
    exit;
}

print 'public key handle: ', $pubKeyHandle, "\n";

# Create an empty SSH key object and tell it to use the PKCS#11 handles, indicating the key type.
my $sshKey = Chilkat2::SshKey->new;
$success = $sshKey->UsePkcs11($pkcs11, $privKeyHandle, $pubKeyHandle, 'rsa');
if (!$success) {
    print $sshKey->LastErrorText, "\n";
    exit;
}

my $ssh = Chilkat2::Ssh->new;

my $port = 22;
$success = $ssh->Connect('ssh.example.com', $port);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# 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) {
    print $ssh->LastErrorText, "\n";
    exit;
}

print "Public-key authentication successful.\n";

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

$ssh->Disconnect();

$pkcs11->Logout();
$pkcs11->CloseSession();