Nitrocli (1) Linux Manual Page

NAME

nitrocli – access Nitrokey devices

SYNOPSIS

nitrocli command [arguments]

DESCRIPTION

nitrocli provides access to Nitrokey devices. It supports the Nitrokey Pro, the Nitrokey Storage, and the Librem Key. It can be used to access the encrypted volume, the one-time password generator, and the password safe.

Device selection

Per default, nitrocli connects to any attached Nitrokey device. You can use the –model, –serial-number and –usb-path options to select the device to connect to. nitrocli fails if more than one attached Nitrokey device matches this filter or if multiple Nitrokey devices are attached and none of the filter options is set. Use the list command to list all attached devices with their USB path, model, and serial number (if available).

OPTIONS

-m, –model librem|pro|storage: Restrict connections to the given device model, see the Device selection section.
–serial-number serial-number: Restrict connections to the given serial number, see the Device selection section. serial-number must be a hex string with an optional 0x prefix. This option can be set multiple times to allow any of the given serial numbers. Nitrokey Storage devices never match this restriction as they do not expose their serial number in the USB device descriptor.
–usb-path usb-path: Restrict connections to the given USB path, see the Device selection section.
–no-cache: If this option is set, nitrocli will not cache any inquired secrets using gpg-agent(1) but ask for them each time they are needed. Note that this option does not cause any cached secrets to be cleared. If a secret is already in the cache it will be ignored, but left otherwise untouched. Use the pin clear command to clear secrets from the cache.
-v, –verbose: Enable additional logging and control its verbosity. Logging enabled through this option will appear on the standard error stream. This option can be supplied multiple times. A single occurrence will show additional warnings. Commands sent to the device will be shown when supplied three times and full device communication is available with four occurrences. Supplying this option five times enables the highest verbosity.
-V, –version: Print the nitrocli version and exit.

COMMANDS

General

nitrocli list [-n|–no-connect]

List all attached Nitrokey devices. This command prints a list of the USB path, the model and the serial number of all attached Nitrokey devices. To access the serial number of a Nitrokey Storage device, nitrocli has to connect to it. To omit the serial number of Nitrokey Storage devices instead of connecting to them, set the –no-connect option.

nitrocli status

Print the status of the connected Nitrokey device, including the stick serial number, the firmware version, and the PIN retry count. If the device is a Nitrokey Storage, also print storage related information including the SD card serial number, the SD card usage during this power cycle, the encryption status, and the status of the volumes.

nitrocli lock

Lock the Nitrokey. This command locks the password safe (see the Password safe section). On the Nitrokey Storage, it will also close any active encrypted or hidden volumes (see the Storage section).

nitrocli reset [–only-aes-key]

Perform a factory reset on the Nitrokey. This command performs a factory reset on the OpenPGP smart card, clears the flash storage and builds a new AES key. The user PIN is reset to 123456, the admin PIN to 12345678.

If the –only-aes-key option is set, the command does not perform a full factory reset but only creates a new AES key. The AES key is for example used to encrypt the password safe.

This command requires the admin PIN. To avoid accidental calls of this command, the user has to enter the PIN even if it has been cached.

Storage

The Nitrokey Storage comes with a storage area. This area is comprised of an unencrypted region and an encrypted one of fixed sizes, each made available to the user in the form of block devices. The encrypted region can optionally further be overlayed with up to four hidden volumes. Because of this overlay (which is required to achieve plausible deniability of the existence of hidden volumes), the burden of ensuring that data on the encrypted volume does not overlap with data on one of the hidden volumes is on the user.

nitrocli unencrypted set mode

Change the read-write mode of the volume. mode is the type of the mode to change to: read-write to make the volume readable and writable or read-only to make it only readable. This command requires the admin PIN.

Note that this command requires firmware version 0.51 or higher. Earlier versions are not supported.

nitrocli encrypted open

 Open the encrypted volume on the Nitrokey Storage. The user PIN that is required to open the volume is queried using pinentry

(1) and cached by gpg-agent(1).

nitrocli encrypted close

 Close the encrypted volume on the Nitrokey Storage.

nitrocli hidden create slot start end

Create a new hidden volume inside the encrypted volume. slot must indicate one of the four available slots. start and end represent, respectively, the start and end position of the hidden volume inside the encrypted volume, as a percentage of the encrypted volume’s size. This command requires a password which is later used to look up the hidden volume to open. Unlike a PIN, this password is not cached by gpg-agent(1).

As a guide line for creating new hidden volumes, the status command provides a range of the SD card that has not been written to during this power cycle.

nitrocli hidden open

 Open a hidden volume. The volume to open is determined based on the password entered, which must have a minimum of six characters. Only one hidden volume can be active at any point in time and previously opened volumes will be automatically closed. Similarly, the encrypted volume will be closed if it was open.

nitrocli hidden close

 Close a hidden volume.

nitrocli fill [-a|–attach

Fills the SD card with random data, overwriting all existing data. This operation takes about one hour to finish for a 16 GiB SD card. It cannot be canceled, even if the nitrocli process is terminated before it finishes.

This command requires the admin PIN. To avoid accidental calls of this command, the user has to enter the PIN even if it has been cached.

If the –attach option is set, this command will not start a new fill operation. Instead it checks whether a fill operation is currently running on the device and shows its progress.

One-time passwords

The Nitrokey Pro, the Nitrokey Storage, and the Librem Key support the generation of one-time passwords using the HOTP algorithm according to RFC 4226 or the TOTP algorithm according to RFC 6238. The required data – a name and the secret – is stored in slots. Currently, the Nitrokey devices provide three HOTP slots and 15 TOTP slots. The slots are numbered per algorithm starting at zero.

The TOTP algorithm is a modified version of the HOTP algorithm that also uses the current time. Therefore, the Nitrokey clock must be synchronized with the clock of the application that requests the one-time password.

nitrocli otp get slot [-a|–algorithm algorithm] [-t|–time time]

Generate a one-time password. slot is the number of the slot to generate the password from. algorithm is the OTP algorithm to use. Possible values are hotp for the HOTP algorithm according to RFC 4226 and totp for the TOTP algorithm according to RFC 6238 (default). Per default, this commands sets the Nitrokey’s time to the system time if the TOTP algorithm is selected. If –time is set, it is set to time instead, which must be a Unix timestamp (i.e., the number of seconds since 1970-01-01 00:00:00 UTC). This command might require the user PIN (see the Configuration section).

Configure a one-time password slot. slot is the number of the slot to configure. name is the name of the slot (may not be empty). secret is the secret value to store in that slot. If secret is set to –, the secret is read from the standard input.

The –format option specifies the format of the secret. If it is set to ascii, each character of the given secret is interpreted as the ASCII code of one byte. If it is set to base32, the secret is interpreted as a base32 string according to RFC 4648. If it is set to hex, every two characters are interpreted as the hexadecimal value of one byte. The default value is base32.

algorithm is the OTP algorithm to use. Possible values are hotp for the HOTP algorithm according to RFC 4226 and totp for the TOTP algorithm according to RFC 6238 (default). digits is the number of digits the one-time password should have. Allowed values are 6 and 8 (default: 6). counter is the initial counter if the HOTP algorithm is used (default: 0). time-window is the time window used with TOTP in seconds (default: 30).

nitrocli otp clear slot [-a|–algorithm algorithm]

Delete the name and the secret stored in a one-time password slot. slot is the number of the slot to clear. algorithm is the OTP algorithm to use. Possible values are hotp for the HOTP algorithm according to RFC 4226 and totp for the TOTP algorithm according to RFC 6238 (default).

nitrocli otp status [-a|–all]

List all OTP slots. If –all is not set, empty slots are ignored.

Configuration

Nitrokey devices have four configuration settings: the Num Lock, Caps Lock and Scroll Lock keys can be mapped to an HOTP slot, and OTP generation can be set to require the user PIN.

nitrocli config get

Print the current Nitrokey configuration.

Update the Nitrokey configuration. This command requires the admin PIN.

With the –num-lock, –caps-lock and –scroll-lock options, the respective bindings can be set. slot is the number of the HOTP slot to bind the key to. If –no-num-lock, –no-caps-lock or –no-scroll-lock is set, the respective binding is disabled. The two corresponding options are mutually exclusive.

If –otp-pin is set, the user PIN will be required to generate one-time passwords using the otp get command. If –no-otp-pin is set, OTP generation can be performed without PIN. These two options are mutually exclusive.

Password safe

The Nitrokey Pro, the Nitrokey Storage, and the Librem Key provide a password safe (PWS) with 16 slots. In each of these slots you can store a name, a login, and a password. The PWS is not encrypted, but it is protected with the user PIN by the firmware. Once the PWS is unlocked by one of the commands listed below, it can be accessed without authentication. You can use the lock command to lock the password safe.

nitrocli pws get slot [-n|–name] [-l|–login] [-p|–password] [-q|–quiet]

Print the content of one PWS slot. slot is the number of the slot. Per default, this command prints the name, the login and the password (in that order). If one or more of the options –name, –login, and –password are set, only the selected fields are printed. The order of the fields never changes.

The fields are printed together with a label. Use the –quiet option to suppress the labels and to only output the values stored in the PWS slot.

nitrocli pws add [-s|–slot slot] name login password|–

Add a new PWS slot. If the –slot option is set, this command writes the data to the given slot and fails if the slot is already programmed. If the –slot option is not set, this command locates the first free PWS slot and sets its content to the given values. It fails if all PWS slots are programmed.

If password is set to –, the password is read from the standard input.

nitrocli pws update slot [-n|–name name] [-l|–login login] [-p|–password password|–]

Update the content of a programmed PWS slot. slot is the number of the slot to write. This command only sets the data given with the –name, –login, and –password options and does not overwrite the other fields of the slot.

If password is set to –, the password is read from the standard input.

nitrocli pws clear slot

Delete the data stored in a PWS slot. slot is the number of the slot clear.

nitrocli pws status [-a|–all]

List all PWS slots. If –all is not set, empty slots are ignored.

PINs

Nitrokey devices have two PINs: the user PIN and the admin PIN. The user PIN must have at least six, the admin PIN at least eight characters. The user PIN is required for commands such as otp get (depending on the configuration) and for all pws commands. The admin PIN is usually required to change the device configuration.

Each PIN has a retry counter that is decreased with every wrong PIN entry and reset if the PIN was entered correctly. The initial retry counter is three. If the retry counter for the user PIN is zero, you can use the pin unblock command to unblock and reset the user PIN. If the retry counter for the admin PIN is zero, you have to perform a factory reset using the reset command or gpg(1). Use the status command to check the retry counters.

nitrocli pin clear: Clear the PINs cached by the other commands. Note that cached PINs are associated with the device they belong to and the clear command will only clear the PIN for the currently used device, not all others.
nitrocli pin set type: Change a PIN. type is the type of the PIN that will be changed: admin to change the admin PIN or user to change the user PIN. This command only works if the retry counter for the PIN type is at least one. (Use the status command to check the retry counters.)
nitrocli pin unblock: Unblock and reset the user PIN. This command requires the admin PIN. The admin PIN cannot be unblocked. This operation is equivalent to the unblock PIN option provided by gpg(1) (using the –change-pin option).

Extensions

In addition to the above built-in commands, nitrocli supports user-provided functionality in the form of extensions. An extension can be any executable file whose filename starts with "nitrocli-" and that is discoverable through lookup via the PATH environment variable. Those executables can be invoked as regular subcommands (without the need of the prefix; e.g., an extension with the name "nitrocli-otp-cache" could be invoked as "nitrocli otp-cache").

More information on how to write extensions can be found in the Extensions section below.

CONFIG FILE

nitrocli tries to read the configuration file at ${XDG_CONFIG_HOME}/nitrocli/config.toml (or ${HOME}/nitrocli/config.toml if the XDG_CONFIG_HOME environment variable is not set). It is used to set default values for the options listed below.

You can also set the environment variable NITROCLI_KEY to overwrite the configuration for key (see the Environment section). Note that command-line arguments overwrite both the configuration file and the environment variables.

The following values can be set in the configuration file:

model: Restrict connections to the given device model (string, default: not set, see –model).
serial_numbers: Restrict connections to the given serial numbers (list of strings, default: empty, see –serial-number).
usb_path: Restrict connections to the given USB path (string, default: not set, see –usb-path).
no_cache: If set to true, do not cache any inquired secrets (boolean, default: false, see –no-cache).
verbosity: Set the log level (integer, default: 0, see –verbose).

The configuration file must use the TOML format, for example:
    model = "pro"
    serial_numbers = ["0xf00baa", "deadbeef"]
    usb_path = "0001:0006:02"
    no_cache = false
    verbosity = 0

ENVIRONMENT

The program honors two sets of environment variables, all prefixed by "NITROCLI_".

Configuration

The first set controls basic configuration of the program. These variables mirror the respective command line options and configuration file settings. They are:

NITROCLI_MODEL: Restrict connections to the given device model (string, default: not set, see –model).
NITROCLI_SERIAL_NUMBERS: Restrict connections to the given list of serial numbers (comma-separated list of strings, default: empty, see –serial-number).
NITROCLI_USB_PATH: Restrict connections to the given USB path (string, default: not set, see –usb-path).
NITROCLI_NO_CACHE: If set to true, do not cache any inquired secrets (boolean, default: false, see –no-cache).
NITROCLI_VERBOSITY: Set the log level (integer, default: 0, see –verbose).

Password & PIN entry

The second set can be used to provide password & PIN data to the program to suppress interactive entry through pinentry(1) for operations that otherwise would ask for it. The following variables are recognized:

NITROCLI_ADMIN_PIN: The admin PIN to use.
NITROCLI_USER_PIN: The user PIN to use.
NITROCLI_NEW_ADMIN_PIN: The new admin PIN to set. This variable is only used by the pin set command for the admin type.
NITROCLI_NEW_USER_PIN: The new user PIN to set. This variable is only used by the pin set command for the user type.
NITROCLI_PASSWORD: A password used by commands that require one (e.g., hidden open).

EXTENSIONS

nitrocli supports user-provided extensions that are executable files whose filename starts with "nitrocli-" and that are discoverable through lookup via the PATH environment variable.

The program conveys basic configuration information to any extension being started this way. Specifically, it will set each environment variable as described in the Configuration subsection of the Environment section above, if the corresponding nitrocli program configuration was set. In addition, the following variables will be set:

NITROCLI_BINARY: The absolute path to the nitrocli binary through which the extension was invoked. This path may be used to recursively invoke nitrocli to implement certain functionality.
NITROCLI_RESOLVED_USB_PATH: The USB path of the device that nitrocli would connect to based on the –model, –serial-number, and –usb-path options. If there is no matching Nitrokey device, or if multiple devices match the options, the environment variable is not set.

All other variables present in the environment will be passed through to the extension verbatim.

Newer versions of the program reserve the right to set additional environment variables inside the "NITROCLI_" namespace. As such, extensions are advised to not define custom variables with this prefix. However, "NITROCLI_EXT_" is provided specifically for this purpose. To further avoid conflicts between extensions, it is recommended that this prefix be followed by the extension’s name (uppercased).

Extensions may optionally read or write persistent data of various forms. Similar to the main program, extensions should follow the XDG Base Directory Specification as a guideline where to store such data. More specifically, the following conventions should be followed:

For configuration data, ${XDG_CONFIG_HOME}/extension/ is the preferred directory, where extension is the full extension name, including the "nitrocli-" prefix. The recommended configuration format is TOML. If only a single configuration file is used, config.toml is the recommended name.

Similarly, regular data should reside in ${XDG_DATA_HOME}/extension/ and cached data be stored in ${XDG_CACHE_HOME}/extension/.

FILES

${XDG_CONFIG_HOME}/nitrocli/config.toml
${HOME}/nitrocli/config.toml: User configuration file, see the Config file section.

EXAMPLES

Storage

Create a hidden volume in the first available slot, starting at half the size of the encrypted volume (i.e., 50%) and stretching all the way to its end (100%):
$ nitrocli hidden create 0 50 100

One-time passwords

Configure a one-time password slot with a hexadecimal secret representation:
    $ nitrocli otp set 0 test-rfc4226 3132333435363738393031323334353637383930 –format hex –algorithm hotp
    $ nitrocli otp set 1 test-foobar 666F6F626172 –format hex –algorithm hotp
    $ nitrocli otp set 0 test-rfc6238 3132333435363738393031323334353637383930 –format hex –algorithm totp –digits 8

Configure a one-time password slot with an ASCII secret representation:
    $ nitrocli otp set 0 test-rfc4226 12345678901234567890 –format ascii –algorithm hotp
    $ nitrocli otp set 1 test-foobar foobar –format ascii –algorithm hotp
    $ nitrocli otp set 0 test-rfc6238 12345678901234567890 –format ascii –algorithm totp –digits 8

Configure a one-time password slot with a base32 secret representation:
    $ nitrocli otp set 0 test-rfc4226 gezdgnbvgy3tqojqgezdgnbvgy3tqojq –algorithm hotp
    $ nitrocli otp set 1 test-foobar mzxw6ytboi====== –algorithm hotp
    $ nitrocli otp set 0 test-rfc6238 gezdgnbvgy3tqojqgezdgnbvgy3tqojq –algorithm totp –digits 8

Generate a one-time password:
    $ nitrocli otp get 0 –algorithm hotp
    755224
    $ nitrocli otp get 0 –algorithm totp –time 1234567890
    89005924

Clear a one-time password slot:
$ nitrocli otp clear 0 –algorithm hotp

Configuration

Query the configuration:
    $ nitrocli config get
    Config:
      numlock binding:          not set
      capslock binding:         not set
      scrollock binding:        not set
      require user PIN for OTP: true

Change the configuration:
$ nitrocli config set –otp-pin

Password safe

Configure a PWS slot:
$ nitrocli pws add example.org john.doe passw0rd
Added PWS slot 0

Get the data from a slot:
    $ nitrocli pws get 0
    name:     example.org
    login:    john.doe
    password: passw0rd

Copy the password to the clipboard (requires xclip(1)).
$ nitrocli pws get 0 –password –quiet | xclip -in

Query the PWS slots:
$ nitrocli pws status
slot name

0 example.org

nitrocli (1) Linux Manual Page

NAME

SYNOPSIS

DESCRIPTION

Device selection

OPTIONS

COMMANDS

General

Storage

One-time passwords

Configuration

Password safe

PINs

Extensions

CONFIG FILE

ENVIRONMENT

Configuration

Password & PIN entry

EXTENSIONS

FILES

EXAMPLES

Storage

One-time passwords

Configuration

Password safe

Index

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