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.

#import <CkoPkcs11.h>
#import <NSString.h>
#import <CkoJsonObject.h>
#import <CkoSshKey.h>
#import <CkoSsh.h>

BOOL success = NO;

//  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.

CkoPkcs11 *pkcs11 = [[CkoPkcs11 alloc] init];

//  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.
NSString *pin = @"0000";

//  Normal user = 1
int userType = 1;

success = [pkcs11 QuickSession: [NSNumber numberWithInt: userType] pin: pin];
if (success == NO) {
    NSLog(@"%@",pkcs11.LastErrorText);
    return;
}

//  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
CkoJsonObject *jsonTemplate = [[CkoJsonObject alloc] init];
[jsonTemplate UpdateString: @"class" value: @"private_key"];
[jsonTemplate UpdateString: @"key_type" value: @"rsa"];
[jsonTemplate UpdateString: @"label" value: @"MySshKey"];

unsigned long privKeyHandle = [pkcs11 FindObject: jsonTemplate];
if (privKeyHandle == 0) {
    NSLog(@"%@",pkcs11.LastErrorText);
    return;
}

//  The handle is only valid for the duration of this PKCS#11 session.  To use the key in a
//  later session, find it again.
NSLog(@"%@%d",@"private key handle: ",privKeyHandle);

//  Find the corresponding public key by changing the class in the same template.
[jsonTemplate UpdateString: @"class" value: @"public_key"];

unsigned long pubKeyHandle = [pkcs11 FindObject: jsonTemplate];
if (pubKeyHandle == 0) {
    NSLog(@"%@",pkcs11.LastErrorText);
    return;
}

NSLog(@"%@%d",@"public key handle: ",pubKeyHandle);

//  Create an empty SSH key object and tell it to use the PKCS#11 handles, indicating the key type.
CkoSshKey *sshKey = [[CkoSshKey alloc] init];
success = [sshKey UsePkcs11: pkcs11 privKeyHandle: privKeyHandle pubKeyHandle: pubKeyHandle keyType: @"rsa"];
if (success == NO) {
    NSLog(@"%@",sshKey.LastErrorText);
    return;
}

CkoSsh *ssh = [[CkoSsh alloc] init];

int port = 22;
success = [ssh Connect: @"ssh.example.com" port: [NSNumber numberWithInt: port]];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

//  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" privateKey: sshKey];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

NSLog(@"%@",@"Public-key authentication successful.");

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

[ssh Disconnect];

[pkcs11 Logout];
[pkcs11 CloseSession];