Objective-C

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.

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Objective-C

#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 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.

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

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

//  Normal user = 1
int userType = 1;

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

//  Describe the private key object to be located on the HSM.
CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json UpdateString: @"class" value: @"private_key"];
[json UpdateString: @"label" value: @"MySshKey"];

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

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

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

//  Create an SSH key object that uses the HSM handles.  The key type may be "rsa" or "ec".
CkoSshKey *key = [[CkoSshKey alloc] init];
NSString *keyType = @"rsa";
success = [key UsePkcs11: pkcs11 privKeyHandle: priv_handle pubKeyHandle: pub_handle keyType: keyType];
if (success == NO) {
    NSLog(@"%@",key.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;
}

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

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

[ssh Disconnect];

[pkcs11 Logout];
[pkcs11 CloseSession];