Nitrokey HSM2 Firmware update and customization for own solution

[szszszsz]

Hi @jochen!

To clarify, for OpenPGP/PKCS communication we have only one product based solely on the MCU, and this is Nitrokey Start. Other products have either real hardware OpenPGP or HSM smart card to store the secrets, and are MCU assisted (being a smart card reader over USB, and providing extra features).

Specifically Nitrokey HSM2 is based on smart card (JavaCard), which firmware is securely update-able through encrypted connection using website. The smart card used is not OpenPGP, but HSM from CardContact, and it’s firmware is closed-source, not directly modifiyable, but seems to support custom applets as far as I understand from the vendor site.

@jochen

If the secure hardware module inside the Nitrokey HSM2 would offer pubkey authentification for decryption, a single master key could be used to encrypt a large amount of subkeys, each used for only a small part of the disk. The master key itself would never leave the HSM and would only be used for decryption of those keys that are needed. Decrypting keys by the HSM requires a valid certificate of the
user that has to be renewed frequently an is only valid for a specified ammount of keys to decrypt.

In order to implement this, one had to add some functionality to the HSM, namely configuring a condition on a key that has to be satisfied by an other operation (cert verification) before the key is unlocked for the requested operation (decryption).

This could be applied to many other use cases that benefit from access control of keys.

So as far as I get this right this would be evolution of standard wrapped asymmetric/symmetric (like RSA/ECC) encryption to asymmetric/asymmetric per block. This is interesting idea.
However have you taken into consideration the performance of the device?

@jochen

Is it open source/possible to customize it?

@sc-hsm: Could you tell is it possible to upload custom applets to the HSM? I did not see that in the documentation.