Why entering invalid SO-PIN in HSM 2 bricks the device?

Nitrokey Support English
#1

I wonder why entering SO-PIN more than 15 times (default value) bricks the device? Is it forced by hardware (i.e. internal smart card works this way) or was that implemented separately? I believe that initializing such device again would wipe data from it, so there should be no problems with it?

#2

Hi!

This is a hardware security latch, which makes smart card unusable. We do not have any method for reinitializing a device with used up attempt counter for SO PIN.

#3

So this is as I suspected. Thank you for an answer.

#4

Can default amount of max tries (times of attempts to enter a pin) be increased in settings?

How many can be set as a maximum retries before it bricks?

#5

It is not possible to change the default attempt count for the SO PIN as far as I see in the manual. For the User PIN I have found Retry Counter Initial Value field in the INITIALIZE DEVICE APDU. Looking at sc-hsm-tool help screen I see its value can be defined during initialization (no range declared):

$ sc-hsm-tool --help
sc-hsm-tool: unrecognized option '--help'
Usage: sc-hsm-tool [OPTIONS]
Options:
  -X, --initialize              Initialize token
  -C, --create-dkek-share <arg>
                                Create DKEK key share and save to <filename>
  -I, --import-dkek-share <arg>
                                Import DKEK key share <filename>
  -W, --wrap-key <arg>          Wrap key and save to <filename>
  -U, --unwrap-key <arg>        Unwrap key read from <filename>
  -s, --dkek-shares <arg>       Number of DKEK shares [No DKEK]
      --so-pin <arg>            Define security officer PIN (SO-PIN)
      --pin <arg>               Define user PIN
      --pin-retry <arg>         Define user PIN retry counter
(...)

$ man sc-hsm-tool
(...)
       --pin-retry value
           Define number of PIN retries for user PIN during initialization. Default is 3.