Nitrokey Start v8 - GNUK 1.2.15

Please follow update guide from previous releases.

1. Increase minimum PIN length to 14 for both Admin and User - see #29;
2. Update to GNUK 1.2.15 (without new chopstx);
3. Update tool UX improved (more information about errors).

Edit: Please remember all user data will be removed during the update. Do not remove device from the USB slot during the update.

Reference update log

cd ../tool && ./upgrade_by_passwd.py -p 12345678 ../prebuilt/RTM.8/{regnual.bin,gnuk.bin}
Provided firmware files:
- ../prebuilt/RTM.8/regnual.bin: 4504
- ../prebuilt/RTM.8/gnuk.bin: 115712
Currently connected device strings:
Device:
    Vendor: Nitrokey
   Product: Nitrokey Start
    Serial: FSIJ-1.2.14-43144852
  Revision: RTM.7
    Config: NITROKEY_START:dfu=no:debug=no:pinpad=no:certdo=yes:factory_reset=yes
       Sys: 3.0
Please note:
- Latest firmware available is: RTM.8 (published: 2020-04-30T15:09:53Z),
 provided firmware: ../prebuilt/RTM.8/gnuk.bin
- All data will be removed from the device
- Do not interrupt the update process, or the device will not run properly
- Whole process should not take more than 1 minute
Do you want to continue? [yes/no]: yes
...
*** Starting bootloader upload procedure
CRC32: d1d535d1

Device:
Configuration: 1
Interface: 0
*** Connected to the device
20002a00:20005000
*** Running update. Do NOT remove the device from the USB slot, until further notice.
Downloading flash upgrade program...
start 20002a00
end   20003b00
Run flash upgrade program...
Waiting for device to appear:
  Wait 20 seconds....

08001000:08020000
Downloading the program
start 08001000
end   0801c400
Protecting device
Finish flashing
Resetting device
Update procedure finished. Device could be removed from USB slot.

Currently connected device strings (after upgrade):
......
*** Please reinsert device to the USB slot
.....
Device:
    Vendor: Nitrokey
   Product: Nitrokey Start
    Serial: FSIJ-1.2.15-43144852
  Revision: RTM.8
    Config: NITROKEY_START:dfu=no:debug=no:pinpad=no:certdo=yes:factory_reset=yes
       Sys: 3.0
Note: power cycle might be needed due to setting RDP flag on MCU, which stalls it

Edit 070520: Please refer to documentation regarding device initialization:

• https://www.nitrokey.com/documentation/installation#p:nitrokey-start (general)
• https://www.nitrokey.com/documentation/installation#p:nitrokey-start&os:linux (for Linux)

Specifically keys have to be imported/generated before setting the User PIN will work.