pico-hsm/doc/extra_command.md

Extra command

Pico HSM supports a customized extra command to use with different options. Since the drivers in the market do not support the following features, a raw APDU command shall be sent.

To send a raw APDU command, opensc-tool -s <APDU> can be used. The APDU parameter is a string of hexadecimal numbers and it takes the following form:

8088XX00YYZZZZRR

It composed by the following fields:

• 80 to indicate that it is a custom vendor type command.
• 88 is the INS custom command.
• XX is the command to execute. It varies depending on the targeted command.
• 00 is the parameter of the command. At this moment, no commands support parameters.
• YY is the length of the data. If no data is provided, this field is absent.
• ZZZZ is the data to be sent. Optional. The length is variable.
• RR is the length of the expected response. If no response is expected, this field is absent.

Real time clock and datetime

Pico HSM has an internal real time clock (RTC) which can track precisely the date and the time. However, when it is reset or powered down, the Pico HSM is reset to the initial datetime: 2020 January 1, 00:00:00.

Getting the datetime

To obtain the current datetime (referenced to 00:00:00 2020/01/01), the XX parameter must be set to 0A. There is no data and, thus, YY and ZZZZ are absent. The expected response is 8 bytes length.

For example, to obtain the current datetime:

$ opensc-tool -s 80880A0008
Using reader with a card: Free Software Initiative of Japan Gnuk
Sending: 80 88 0A 00 08 
Received (SW1=0x90, SW2=0x00):
07 E6 04 06 03 13 29 1E ......).

The response is composed by 8 bytes:

• The first two bytes are the current year, MSB first. Hence, 07E6h equals to 2022.
• 1 byte for the current month, 01h is January and 0Ch is December.
• 1 byte for the current day, from 01h (1) to 1Fh (31).
• 1 byte for the day of the week, 00h is Sunday, 01h is Monday, etc.
• 1 byte for the hours, from 00h (0) to 17h (23).
• 1 byte for the minutes, from 00h (0) to 3Bh (59).
• 1 byte for the seconds, from 00h (0) to 3Bh (59).

If the command is correctly received, SW1=0x90 and SW2=0x00. Other values mean that an error has ocurred.

Setting the datetime

To set the reference datetime, a datetime string must be provided. For example:

$ opensc-tool -s 80880A000807E6040603132917
Using reader with a card: Free Software Initiative of Japan Gnuk
Sending: 80 88 0A 00 08 07 E6 04 06 03 13 29 17 
Received (SW1=0x90, SW2=0x00)

will set the reference datetime to Wednesday, 2022 April 6th, 19:41:23.