Refactor the device module into submodules

This patch splits the rather large device module into the submodules
pro, storage and wrapper.  This only changes the internal code structure
and does not affect the public API.

4 files changed, 1414 insertions, 0 deletions

diff --git a/src/device/mod.rs b/src/device/mod.rs
new file mode 100644
index 0000000..af28ab5
--- /dev/null
+++ b/src/device/mod.rs
@@ -0,0 +1,466 @@
+// Copyright (C) 2018-2019 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: MIT
+
+mod pro;
+mod storage;
+mod wrapper;
+
+use std::fmt;
+
+use libc;
+use nitrokey_sys;
+
+use crate::auth::Authenticate;
+use crate::config::{Config, RawConfig};
+use crate::error::{CommunicationError, Error};
+use crate::otp::GenerateOtp;
+use crate::pws::GetPasswordSafe;
+use crate::util::{
+    get_command_result, get_cstring, get_last_error, result_from_string, result_or_error,
+};
+
+pub use pro::Pro;
+pub use storage::{
+    SdCardData, Storage, StorageProductionInfo, StorageStatus, VolumeMode, VolumeStatus,
+};
+pub use wrapper::DeviceWrapper;
+
+/// Available Nitrokey models.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Model {
+    /// The Nitrokey Storage.
+    Storage,
+    /// The Nitrokey Pro.
+    Pro,
+}
+
+impl fmt::Display for Model {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(match *self {
+            Model::Pro => "Pro",
+            Model::Storage => "Storage",
+        })
+    }
+}
+
+/// A firmware version for a Nitrokey device.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct FirmwareVersion {
+    /// The major firmware version, e. g. 0 in v0.40.
+    pub major: u8,
+    /// The minor firmware version, e. g. 40 in v0.40.
+    pub minor: u8,
+}
+
+impl fmt::Display for FirmwareVersion {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "v{}.{}", self.major, self.minor)
+    }
+}
+
+/// A Nitrokey device.
+///
+/// This trait provides the commands that can be executed without authentication and that are
+/// present on all supported Nitrokey devices.
+pub trait Device<'a>: Authenticate<'a> + GetPasswordSafe<'a> + GenerateOtp + fmt::Debug {
+    /// Returns the [`Manager`][] instance that has been used to connect to this device.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use nitrokey::{Device, DeviceWrapper};
+    ///
+    /// fn do_something(device: DeviceWrapper) {
+    ///     // reconnect to any device
+    ///     let manager = device.into_manager();
+    ///     let device = manager.connect();
+    ///     // do something with the device
+    ///     // ...
+    /// }
+    ///
+    /// # fn main() -> Result<(), nitrokey::Error> {
+    /// match nitrokey::take()?.connect() {
+    ///     Ok(device) => do_something(device),
+    ///     Err(err) => println!("Could not connect to a Nitrokey: {}", err),
+    /// }
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn into_manager(self) -> &'a mut crate::Manager;
+
+    /// Returns the model of the connected Nitrokey device.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect()?;
+    /// println!("Connected to a Nitrokey {}", device.get_model());
+    /// #    Ok(())
+    /// # }
+    fn get_model(&self) -> Model;
+
+    /// Returns the serial number of the Nitrokey device.  The serial number is the string
+    /// representation of a hex number.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect()?;
+    /// match device.get_serial_number() {
+    ///     Ok(number) => println!("serial no: {}", number),
+    ///     Err(err) => eprintln!("Could not get serial number: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn get_serial_number(&self) -> Result<String, Error> {
+        result_from_string(unsafe { nitrokey_sys::NK_device_serial_number() })
+    }
+
+    /// Returns the number of remaining authentication attempts for the user.  The total number of
+    /// available attempts is three.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect()?;
+    /// let count = device.get_user_retry_count();
+    /// match device.get_user_retry_count() {
+    ///     Ok(count) => println!("{} remaining authentication attempts (user)", count),
+    ///     Err(err) => eprintln!("Could not get user retry count: {}", err),
+    /// }
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn get_user_retry_count(&self) -> Result<u8, Error> {
+        result_or_error(unsafe { nitrokey_sys::NK_get_user_retry_count() })
+    }
+
+    /// Returns the number of remaining authentication attempts for the admin.  The total number of
+    /// available attempts is three.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect()?;
+    /// let count = device.get_admin_retry_count();
+    /// match device.get_admin_retry_count() {
+    ///     Ok(count) => println!("{} remaining authentication attempts (admin)", count),
+    ///     Err(err) => eprintln!("Could not get admin retry count: {}", err),
+    /// }
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn get_admin_retry_count(&self) -> Result<u8, Error> {
+        result_or_error(unsafe { nitrokey_sys::NK_get_admin_retry_count() })
+    }
+
+    /// Returns the firmware version.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect()?;
+    /// match device.get_firmware_version() {
+    ///     Ok(version) => println!("Firmware version: {}", version),
+    ///     Err(err) => eprintln!("Could not access firmware version: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn get_firmware_version(&self) -> Result<FirmwareVersion, Error> {
+        let major = result_or_error(unsafe { nitrokey_sys::NK_get_major_firmware_version() })?;
+        let minor = result_or_error(unsafe { nitrokey_sys::NK_get_minor_firmware_version() })?;
+        Ok(FirmwareVersion { major, minor })
+    }
+
+    /// Returns the current configuration of the Nitrokey device.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect()?;
+    /// let config = device.get_config()?;
+    /// println!("numlock binding:          {:?}", config.numlock);
+    /// println!("capslock binding:         {:?}", config.capslock);
+    /// println!("scrollock binding:        {:?}", config.scrollock);
+    /// println!("require password for OTP: {:?}", config.user_password);
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn get_config(&self) -> Result<Config, Error> {
+        let config_ptr = unsafe { nitrokey_sys::NK_read_config() };
+        if config_ptr.is_null() {
+            return Err(get_last_error());
+        }
+        let config_array_ptr = config_ptr as *const [u8; 5];
+        let raw_config = unsafe { RawConfig::from(*config_array_ptr) };
+        unsafe { libc::free(config_ptr as *mut libc::c_void) };
+        Ok(raw_config.into())
+    }
+
+    /// Changes the administrator PIN.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
+    /// - [`WrongPassword`][] if the current admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect()?;
+    /// match device.change_admin_pin("12345678", "12345679") {
+    ///     Ok(()) => println!("Updated admin PIN."),
+    ///     Err(err) => eprintln!("Failed to update admin PIN: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    fn change_admin_pin(&mut self, current: &str, new: &str) -> Result<(), Error> {
+        let current_string = get_cstring(current)?;
+        let new_string = get_cstring(new)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_change_admin_PIN(current_string.as_ptr(), new_string.as_ptr())
+        })
+    }
+
+    /// Changes the user PIN.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
+    /// - [`WrongPassword`][] if the current user password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect()?;
+    /// match device.change_user_pin("123456", "123457") {
+    ///     Ok(()) => println!("Updated admin PIN."),
+    ///     Err(err) => eprintln!("Failed to update admin PIN: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    fn change_user_pin(&mut self, current: &str, new: &str) -> Result<(), Error> {
+        let current_string = get_cstring(current)?;
+        let new_string = get_cstring(new)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_change_user_PIN(current_string.as_ptr(), new_string.as_ptr())
+        })
+    }
+
+    /// Unlocks the user PIN after three failed login attempts and sets it to the given value.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
+    /// - [`WrongPassword`][] if the admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect()?;
+    /// match device.unlock_user_pin("12345678", "123456") {
+    ///     Ok(()) => println!("Unlocked user PIN."),
+    ///     Err(err) => eprintln!("Failed to unlock user PIN: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    fn unlock_user_pin(&mut self, admin_pin: &str, user_pin: &str) -> Result<(), Error> {
+        let admin_pin_string = get_cstring(admin_pin)?;
+        let user_pin_string = get_cstring(user_pin)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_unlock_user_password(
+                admin_pin_string.as_ptr(),
+                user_pin_string.as_ptr(),
+            )
+        })
+    }
+
+    /// Locks the Nitrokey device.
+    ///
+    /// This disables the password store if it has been unlocked.  On the Nitrokey Storage, this
+    /// also disables the volumes if they have been enabled.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect()?;
+    /// match device.lock() {
+    ///     Ok(()) => println!("Locked the Nitrokey device."),
+    ///     Err(err) => eprintln!("Could not lock the Nitrokey device: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    fn lock(&mut self) -> Result<(), Error> {
+        get_command_result(unsafe { nitrokey_sys::NK_lock_device() })
+    }
+
+    /// Performs a factory reset on the Nitrokey device.
+    ///
+    /// This commands performs a factory reset on the smart card (like the factory reset via `gpg
+    /// --card-edit`) and then clears the flash memory (password safe, one-time passwords etc.).
+    /// After a factory reset, [`build_aes_key`][] has to be called before the password safe or the
+    /// encrypted volume can be used.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    /// - [`WrongPassword`][] if the admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect()?;
+    /// match device.factory_reset("12345678") {
+    ///     Ok(()) => println!("Performed a factory reset."),
+    ///     Err(err) => eprintln!("Could not perform a factory reset: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`build_aes_key`]: #method.build_aes_key
+    fn factory_reset(&mut self, admin_pin: &str) -> Result<(), Error> {
+        let admin_pin_string = get_cstring(admin_pin)?;
+        get_command_result(unsafe { nitrokey_sys::NK_factory_reset(admin_pin_string.as_ptr()) })
+    }
+
+    /// Builds a new AES key on the Nitrokey.
+    ///
+    /// The AES key is used to encrypt the password safe and the encrypted volume.  You may need
+    /// to call this method after a factory reset, either using [`factory_reset`][] or using `gpg
+    /// --card-edit`.  You can also use it to destroy the data stored in the password safe or on
+    /// the encrypted volume.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    /// - [`WrongPassword`][] if the admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::Device;
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect()?;
+    /// match device.build_aes_key("12345678") {
+    ///     Ok(()) => println!("New AES keys have been built."),
+    ///     Err(err) => eprintln!("Could not build new AES keys: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`factory_reset`]: #method.factory_reset
+    fn build_aes_key(&mut self, admin_pin: &str) -> Result<(), Error> {
+        let admin_pin_string = get_cstring(admin_pin)?;
+        get_command_result(unsafe { nitrokey_sys::NK_build_aes_key(admin_pin_string.as_ptr()) })
+    }
+}
+
+fn get_connected_model() -> Option<Model> {
+    match unsafe { nitrokey_sys::NK_get_device_model() } {
+        nitrokey_sys::NK_device_model_NK_PRO => Some(Model::Pro),
+        nitrokey_sys::NK_device_model_NK_STORAGE => Some(Model::Storage),
+        _ => None,
+    }
+}
+
+pub(crate) fn create_device_wrapper(
+    manager: &mut crate::Manager,
+    model: Model,
+) -> DeviceWrapper<'_> {
+    match model {
+        Model::Pro => Pro::new(manager).into(),
+        Model::Storage => Storage::new(manager).into(),
+    }
+}
+
+pub(crate) fn get_connected_device(
+    manager: &mut crate::Manager,
+) -> Result<DeviceWrapper<'_>, Error> {
+    match get_connected_model() {
+        Some(model) => Ok(create_device_wrapper(manager, model)),
+        None => Err(CommunicationError::NotConnected.into()),
+    }
+}
+
+pub(crate) fn connect_enum(model: Model) -> bool {
+    let model = match model {
+        Model::Storage => nitrokey_sys::NK_device_model_NK_STORAGE,
+        Model::Pro => nitrokey_sys::NK_device_model_NK_PRO,
+    };
+    unsafe { nitrokey_sys::NK_login_enum(model) == 1 }
+}
diff --git a/src/device/pro.rs b/src/device/pro.rs
new file mode 100644
index 0000000..a65345e
--- /dev/null
+++ b/src/device/pro.rs
@@ -0,0 +1,79 @@
+// Copyright (C) 2018-2019 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: MIT
+
+use nitrokey_sys;
+
+use crate::device::{Device, Model};
+use crate::otp::GenerateOtp;
+
+/// A Nitrokey Pro device without user or admin authentication.
+///
+/// Use the [`connect`][] method to obtain an instance wrapper or the [`connect_pro`] method to
+/// directly obtain an instance.  If you want to execute a command that requires user or admin
+/// authentication, use [`authenticate_admin`][] or [`authenticate_user`][].
+///
+/// # Examples
+///
+/// Authentication with error handling:
+///
+/// ```no_run
+/// use nitrokey::{Authenticate, User, Pro};
+/// # use nitrokey::Error;
+///
+/// fn perform_user_task<'a>(device: &User<'a, Pro<'a>>) {}
+/// fn perform_other_task(device: &Pro) {}
+///
+/// # fn try_main() -> Result<(), Error> {
+/// let mut manager = nitrokey::take()?;
+/// let device = manager.connect_pro()?;
+/// let device = match device.authenticate_user("123456") {
+///     Ok(user) => {
+///         perform_user_task(&user);
+///         user.device()
+///     },
+///     Err((device, err)) => {
+///         eprintln!("Could not authenticate as user: {}", err);
+///         device
+///     },
+/// };
+/// perform_other_task(&device);
+/// #     Ok(())
+/// # }
+/// ```
+///
+/// [`authenticate_admin`]: trait.Authenticate.html#method.authenticate_admin
+/// [`authenticate_user`]: trait.Authenticate.html#method.authenticate_user
+/// [`connect`]: struct.Manager.html#method.connect
+/// [`connect_pro`]: struct.Manager.html#method.connect_pro
+#[derive(Debug)]
+pub struct Pro<'a> {
+    manager: Option<&'a mut crate::Manager>,
+}
+
+impl<'a> Pro<'a> {
+    pub(crate) fn new(manager: &'a mut crate::Manager) -> Pro<'a> {
+        Pro {
+            manager: Some(manager),
+        }
+    }
+}
+
+impl<'a> Drop for Pro<'a> {
+    fn drop(&mut self) {
+        unsafe {
+            nitrokey_sys::NK_logout();
+        }
+    }
+}
+
+impl<'a> Device<'a> for Pro<'a> {
+    fn into_manager(mut self) -> &'a mut crate::Manager {
+        self.manager.take().unwrap()
+    }
+
+    fn get_model(&self) -> Model {
+        Model::Pro
+    }
+}
+
+impl<'a> GenerateOtp for Pro<'a> {}
diff --git a/src/device/storage.rs b/src/device/storage.rs
new file mode 100644
index 0000000..370ce36
--- /dev/null
+++ b/src/device/storage.rs
@@ -0,0 +1,735 @@
+// Copyright (C) 2018-2019 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: MIT
+
+use std::fmt;
+
+use nitrokey_sys;
+
+use crate::device::{Device, FirmwareVersion, Model};
+use crate::error::Error;
+use crate::otp::GenerateOtp;
+use crate::util::{get_command_result, get_cstring};
+
+/// A Nitrokey Storage device without user or admin authentication.
+///
+/// Use the [`connect`][] method to obtain an instance wrapper or the [`connect_storage`] method to
+/// directly obtain an instance.  If you want to execute a command that requires user or admin
+/// authentication, use [`authenticate_admin`][] or [`authenticate_user`][].
+///
+/// # Examples
+///
+/// Authentication with error handling:
+///
+/// ```no_run
+/// use nitrokey::{Authenticate, User, Storage};
+/// # use nitrokey::Error;
+///
+/// fn perform_user_task<'a>(device: &User<'a, Storage<'a>>) {}
+/// fn perform_other_task(device: &Storage) {}
+///
+/// # fn try_main() -> Result<(), Error> {
+/// let mut manager = nitrokey::take()?;
+/// let device = manager.connect_storage()?;
+/// let device = match device.authenticate_user("123456") {
+///     Ok(user) => {
+///         perform_user_task(&user);
+///         user.device()
+///     },
+///     Err((device, err)) => {
+///         eprintln!("Could not authenticate as user: {}", err);
+///         device
+///     },
+/// };
+/// perform_other_task(&device);
+/// #     Ok(())
+/// # }
+/// ```
+///
+/// [`authenticate_admin`]: trait.Authenticate.html#method.authenticate_admin
+/// [`authenticate_user`]: trait.Authenticate.html#method.authenticate_user
+/// [`connect`]: struct.Manager.html#method.connect
+/// [`connect_storage`]: struct.Manager.html#method.connect_storage
+#[derive(Debug)]
+pub struct Storage<'a> {
+    manager: Option<&'a mut crate::Manager>,
+}
+
+/// The access mode of a volume on the Nitrokey Storage.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum VolumeMode {
+    /// A read-only volume.
+    ReadOnly,
+    /// A read-write volume.
+    ReadWrite,
+}
+
+impl fmt::Display for VolumeMode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(match *self {
+            VolumeMode::ReadOnly => "read-only",
+            VolumeMode::ReadWrite => "read-write",
+        })
+    }
+}
+
+/// The status of a volume on a Nitrokey Storage device.
+#[derive(Debug)]
+pub struct VolumeStatus {
+    /// Indicates whether the volume is read-only.
+    pub read_only: bool,
+    /// Indicates whether the volume is active.
+    pub active: bool,
+}
+
+/// Information about the SD card in a Storage device.
+#[derive(Debug)]
+pub struct SdCardData {
+    /// The serial number of the SD card.
+    pub serial_number: u32,
+    /// The size of the SD card in GB.
+    pub size: u8,
+    /// The year the card was manufactured, e. g. 17 for 2017.
+    pub manufacturing_year: u8,
+    /// The month the card was manufactured.
+    pub manufacturing_month: u8,
+    /// The OEM ID.
+    pub oem: u16,
+    /// The manufacturer ID.
+    pub manufacturer: u8,
+}
+
+/// Production information for a Storage device.
+#[derive(Debug)]
+pub struct StorageProductionInfo {
+    /// The firmware version.
+    pub firmware_version: FirmwareVersion,
+    /// The internal firmware version.
+    pub firmware_version_internal: u8,
+    /// The serial number of the CPU.
+    pub serial_number_cpu: u32,
+    /// Information about the SD card.
+    pub sd_card: SdCardData,
+}
+
+/// The status of a Nitrokey Storage device.
+#[derive(Debug)]
+pub struct StorageStatus {
+    /// The status of the unencrypted volume.
+    pub unencrypted_volume: VolumeStatus,
+    /// The status of the encrypted volume.
+    pub encrypted_volume: VolumeStatus,
+    /// The status of the hidden volume.
+    pub hidden_volume: VolumeStatus,
+    /// The firmware version.
+    pub firmware_version: FirmwareVersion,
+    /// Indicates whether the firmware is locked.
+    pub firmware_locked: bool,
+    /// The serial number of the SD card in the Storage stick.
+    pub serial_number_sd_card: u32,
+    /// The serial number of the smart card in the Storage stick.
+    pub serial_number_smart_card: u32,
+    /// The number of remaining login attempts for the user PIN.
+    pub user_retry_count: u8,
+    /// The number of remaining login attempts for the admin PIN.
+    pub admin_retry_count: u8,
+    /// Indicates whether a new SD card was found.
+    pub new_sd_card_found: bool,
+    /// Indicates whether the SD card is filled with random characters.
+    pub filled_with_random: bool,
+    /// Indicates whether the stick has been initialized by generating
+    /// the AES keys.
+    pub stick_initialized: bool,
+}
+
+impl<'a> Storage<'a> {
+    pub(crate) fn new(manager: &'a mut crate::Manager) -> Storage<'a> {
+        Storage {
+            manager: Some(manager),
+        }
+    }
+
+    /// Changes the update PIN.
+    ///
+    /// The update PIN is used to enable firmware updates.  Unlike the user and the admin PIN, the
+    /// update PIN is not managed by the OpenPGP smart card but by the Nitrokey firmware.  There is
+    /// no retry counter as with the other PIN types.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
+    /// - [`WrongPassword`][] if the current update password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// match device.change_update_pin("12345678", "87654321") {
+    ///     Ok(()) => println!("Updated update PIN."),
+    ///     Err(err) => eprintln!("Failed to update update PIN: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn change_update_pin(&mut self, current: &str, new: &str) -> Result<(), Error> {
+        let current_string = get_cstring(current)?;
+        let new_string = get_cstring(new)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_change_update_password(current_string.as_ptr(), new_string.as_ptr())
+        })
+    }
+
+    /// Enables the firmware update mode.
+    ///
+    /// During firmware update mode, the Nitrokey can no longer be accessed using HID commands.
+    /// To resume normal operation, run `dfu-programmer at32uc3a3256s launch`.  In order to enter
+    /// the firmware update mode, you need the update password that can be changed using the
+    /// [`change_update_pin`][] method.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
+    /// - [`WrongPassword`][] if the current update password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// match device.enable_firmware_update("12345678") {
+    ///     Ok(()) => println!("Nitrokey entered update mode."),
+    ///     Err(err) => eprintln!("Could not enter update mode: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn enable_firmware_update(&mut self, update_pin: &str) -> Result<(), Error> {
+        let update_pin_string = get_cstring(update_pin)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_enable_firmware_update(update_pin_string.as_ptr())
+        })
+    }
+
+    /// Enables the encrypted storage volume.
+    ///
+    /// Once the encrypted volume is enabled, it is presented to the operating system as a block
+    /// device.  The API does not provide any information on the name or path of this block device.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    /// - [`WrongPassword`][] if the provided user password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// match device.enable_encrypted_volume("123456") {
+    ///     Ok(()) => println!("Enabled the encrypted volume."),
+    ///     Err(err) => eprintln!("Could not enable the encrypted volume: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn enable_encrypted_volume(&mut self, user_pin: &str) -> Result<(), Error> {
+        let user_pin = get_cstring(user_pin)?;
+        get_command_result(unsafe { nitrokey_sys::NK_unlock_encrypted_volume(user_pin.as_ptr()) })
+    }
+
+    /// Disables the encrypted storage volume.
+    ///
+    /// Once the volume is disabled, it can be no longer accessed as a block device.  If the
+    /// encrypted volume has not been enabled, this method still returns a success.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// fn use_volume() {}
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// match device.enable_encrypted_volume("123456") {
+    ///     Ok(()) => {
+    ///         println!("Enabled the encrypted volume.");
+    ///         use_volume();
+    ///         match device.disable_encrypted_volume() {
+    ///             Ok(()) => println!("Disabled the encrypted volume."),
+    ///             Err(err) => {
+    ///                 eprintln!("Could not disable the encrypted volume: {}", err);
+    ///             },
+    ///         };
+    ///     },
+    ///     Err(err) => eprintln!("Could not enable the encrypted volume: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn disable_encrypted_volume(&mut self) -> Result<(), Error> {
+        get_command_result(unsafe { nitrokey_sys::NK_lock_encrypted_volume() })
+    }
+
+    /// Enables a hidden storage volume.
+    ///
+    /// This function will only succeed if the encrypted storage ([`enable_encrypted_volume`][]) or
+    /// another hidden volume has been enabled previously.  Once the hidden volume is enabled, it
+    /// is presented to the operating system as a block device and any previously opened encrypted
+    /// or hidden volumes are closed.  The API does not provide any information on the name or path
+    /// of this block device.
+    ///
+    /// Note that the encrypted and the hidden volumes operate on the same storage area, so using
+    /// both at the same time might lead to data loss.
+    ///
+    /// The hidden volume to unlock is selected based on the provided password.
+    ///
+    /// # Errors
+    ///
+    /// - [`AesDecryptionFailed`][] if the encrypted storage has not been opened before calling
+    ///   this method or the AES key has not been built
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// device.enable_encrypted_volume("123445")?;
+    /// match device.enable_hidden_volume("hidden-pw") {
+    ///     Ok(()) => println!("Enabled a hidden volume."),
+    ///     Err(err) => eprintln!("Could not enable the hidden volume: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`enable_encrypted_volume`]: #method.enable_encrypted_volume
+    /// [`AesDecryptionFailed`]: enum.CommandError.html#variant.AesDecryptionFailed
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    pub fn enable_hidden_volume(&mut self, volume_password: &str) -> Result<(), Error> {
+        let volume_password = get_cstring(volume_password)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_unlock_hidden_volume(volume_password.as_ptr())
+        })
+    }
+
+    /// Disables a hidden storage volume.
+    ///
+    /// Once the volume is disabled, it can be no longer accessed as a block device.  If no hidden
+    /// volume has been enabled, this method still returns a success.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// fn use_volume() {}
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// device.enable_encrypted_volume("123445")?;
+    /// match device.enable_hidden_volume("hidden-pw") {
+    ///     Ok(()) => {
+    ///         println!("Enabled the hidden volume.");
+    ///         use_volume();
+    ///         match device.disable_hidden_volume() {
+    ///             Ok(()) => println!("Disabled the hidden volume."),
+    ///             Err(err) => {
+    ///                 eprintln!("Could not disable the hidden volume: {}", err);
+    ///             },
+    ///         };
+    ///     },
+    ///     Err(err) => eprintln!("Could not enable the hidden volume: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn disable_hidden_volume(&mut self) -> Result<(), Error> {
+        get_command_result(unsafe { nitrokey_sys::NK_lock_hidden_volume() })
+    }
+
+    /// Creates a hidden volume.
+    ///
+    /// The volume is crated in the given slot and in the given range of the available memory,
+    /// where `start` is the start position as a percentage of the available memory, and `end` is
+    /// the end position as a percentage of the available memory.  The volume will be protected by
+    /// the given password.
+    ///
+    /// Note that the encrypted and the hidden volumes operate on the same storage area, so using
+    /// both at the same time might lead to data loss.
+    ///
+    /// According to the libnitrokey documentation, this function only works if the encrypted
+    /// storage has been opened.
+    ///
+    /// # Errors
+    ///
+    /// - [`AesDecryptionFailed`][] if the encrypted storage has not been opened before calling
+    ///   this method or the AES key has not been built
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// device.enable_encrypted_volume("123445")?;
+    /// device.create_hidden_volume(0, 0, 100, "hidden-pw")?;
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`AesDecryptionFailed`]: enum.CommandError.html#variant.AesDecryptionFailed
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    pub fn create_hidden_volume(
+        &mut self,
+        slot: u8,
+        start: u8,
+        end: u8,
+        password: &str,
+    ) -> Result<(), Error> {
+        let password = get_cstring(password)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_create_hidden_volume(slot, start, end, password.as_ptr())
+        })
+    }
+
+    /// Sets the access mode of the unencrypted volume.
+    ///
+    /// This command will reconnect the unencrypted volume so buffers should be flushed before
+    /// calling it.  Since firmware version v0.51, this command requires the admin PIN.  Older
+    /// firmware versions are not supported.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    /// - [`WrongPassword`][] if the provided admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    /// use nitrokey::VolumeMode;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// match device.set_unencrypted_volume_mode("12345678", VolumeMode::ReadWrite) {
+    ///     Ok(()) => println!("Set the unencrypted volume to read-write mode."),
+    ///     Err(err) => eprintln!("Could not set the unencrypted volume to read-write mode: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn set_unencrypted_volume_mode(
+        &mut self,
+        admin_pin: &str,
+        mode: VolumeMode,
+    ) -> Result<(), Error> {
+        let admin_pin = get_cstring(admin_pin)?;
+        let result = match mode {
+            VolumeMode::ReadOnly => unsafe {
+                nitrokey_sys::NK_set_unencrypted_read_only_admin(admin_pin.as_ptr())
+            },
+            VolumeMode::ReadWrite => unsafe {
+                nitrokey_sys::NK_set_unencrypted_read_write_admin(admin_pin.as_ptr())
+            },
+        };
+        get_command_result(result)
+    }
+
+    /// Sets the access mode of the encrypted volume.
+    ///
+    /// This command will reconnect the encrypted volume so buffers should be flushed before
+    /// calling it.  It is only available in firmware version 0.49.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    /// - [`WrongPassword`][] if the provided admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    /// use nitrokey::VolumeMode;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// match device.set_encrypted_volume_mode("12345678", VolumeMode::ReadWrite) {
+    ///     Ok(()) => println!("Set the encrypted volume to read-write mode."),
+    ///     Err(err) => eprintln!("Could not set the encrypted volume to read-write mode: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn set_encrypted_volume_mode(
+        &mut self,
+        admin_pin: &str,
+        mode: VolumeMode,
+    ) -> Result<(), Error> {
+        let admin_pin = get_cstring(admin_pin)?;
+        let result = match mode {
+            VolumeMode::ReadOnly => unsafe {
+                nitrokey_sys::NK_set_encrypted_read_only(admin_pin.as_ptr())
+            },
+            VolumeMode::ReadWrite => unsafe {
+                nitrokey_sys::NK_set_encrypted_read_write(admin_pin.as_ptr())
+            },
+        };
+        get_command_result(result)
+    }
+
+    /// Returns the status of the connected storage device.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// fn use_volume() {}
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect_storage()?;
+    /// match device.get_status() {
+    ///     Ok(status) => {
+    ///         println!("SD card ID: {:#x}", status.serial_number_sd_card);
+    ///     },
+    ///     Err(err) => eprintln!("Could not get Storage status: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn get_status(&self) -> Result<StorageStatus, Error> {
+        let mut raw_status = nitrokey_sys::NK_storage_status {
+            unencrypted_volume_read_only: false,
+            unencrypted_volume_active: false,
+            encrypted_volume_read_only: false,
+            encrypted_volume_active: false,
+            hidden_volume_read_only: false,
+            hidden_volume_active: false,
+            firmware_version_major: 0,
+            firmware_version_minor: 0,
+            firmware_locked: false,
+            serial_number_sd_card: 0,
+            serial_number_smart_card: 0,
+            user_retry_count: 0,
+            admin_retry_count: 0,
+            new_sd_card_found: false,
+            filled_with_random: false,
+            stick_initialized: false,
+        };
+        let raw_result = unsafe { nitrokey_sys::NK_get_status_storage(&mut raw_status) };
+        get_command_result(raw_result).map(|_| StorageStatus::from(raw_status))
+    }
+
+    /// Returns the production information for the connected storage device.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// fn use_volume() {}
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let device = manager.connect_storage()?;
+    /// match device.get_production_info() {
+    ///     Ok(data) => {
+    ///         println!("SD card ID:   {:#x}", data.sd_card.serial_number);
+    ///         println!("SD card size: {} GB", data.sd_card.size);
+    ///     },
+    ///     Err(err) => eprintln!("Could not get Storage production info: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn get_production_info(&self) -> Result<StorageProductionInfo, Error> {
+        let mut raw_data = nitrokey_sys::NK_storage_ProductionTest {
+            FirmwareVersion_au8: [0, 2],
+            FirmwareVersionInternal_u8: 0,
+            SD_Card_Size_u8: 0,
+            CPU_CardID_u32: 0,
+            SmartCardID_u32: 0,
+            SD_CardID_u32: 0,
+            SC_UserPwRetryCount: 0,
+            SC_AdminPwRetryCount: 0,
+            SD_Card_ManufacturingYear_u8: 0,
+            SD_Card_ManufacturingMonth_u8: 0,
+            SD_Card_OEM_u16: 0,
+            SD_WriteSpeed_u16: 0,
+            SD_Card_Manufacturer_u8: 0,
+        };
+        let raw_result = unsafe { nitrokey_sys::NK_get_storage_production_info(&mut raw_data) };
+        get_command_result(raw_result).map(|_| StorageProductionInfo::from(raw_data))
+    }
+
+    /// Clears the warning for a new SD card.
+    ///
+    /// The Storage status contains a field for a new SD card warning.  After a factory reset, the
+    /// field is set to true.  After filling the SD card with random data, it is set to false.
+    /// This method can be used to set it to false without filling the SD card with random data.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the provided password contains a null byte
+    /// - [`WrongPassword`][] if the provided admin password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nitrokey::Error;
+    ///
+    /// # fn try_main() -> Result<(), Error> {
+    /// let mut manager = nitrokey::take()?;
+    /// let mut device = manager.connect_storage()?;
+    /// match device.clear_new_sd_card_warning("12345678") {
+    ///     Ok(()) => println!("Cleared the new SD card warning."),
+    ///     Err(err) => eprintln!("Could not set the clear the new SD card warning: {}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn clear_new_sd_card_warning(&mut self, admin_pin: &str) -> Result<(), Error> {
+        let admin_pin = get_cstring(admin_pin)?;
+        get_command_result(unsafe {
+            nitrokey_sys::NK_clear_new_sd_card_warning(admin_pin.as_ptr())
+        })
+    }
+
+    /// Blinks the red and green LED alternatively and infinitely until the device is reconnected.
+    pub fn wink(&mut self) -> Result<(), Error> {
+        get_command_result(unsafe { nitrokey_sys::NK_wink() })
+    }
+
+    /// Exports the firmware to the unencrypted volume.
+    ///
+    /// This command requires the admin PIN.  The unencrypted volume must be in read-write mode
+    /// when this command is executed.  Otherwise, it will still return `Ok` but not write the
+    /// firmware.
+    ///
+    /// This command unmounts the unencrypted volume if it has been mounted, so all buffers should
+    /// be flushed.  The firmware is written to the `firmware.bin` file on the unencrypted volume.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
+    /// - [`WrongPassword`][] if the admin password is wrong
+    ///
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    pub fn export_firmware(&mut self, admin_pin: &str) -> Result<(), Error> {
+        let admin_pin_string = get_cstring(admin_pin)?;
+        get_command_result(unsafe { nitrokey_sys::NK_export_firmware(admin_pin_string.as_ptr()) })
+    }
+}
+
+impl<'a> Drop for Storage<'a> {
+    fn drop(&mut self) {
+        unsafe {
+            nitrokey_sys::NK_logout();
+        }
+    }
+}
+
+impl<'a> Device<'a> for Storage<'a> {
+    fn into_manager(mut self) -> &'a mut crate::Manager {
+        self.manager.take().unwrap()
+    }
+
+    fn get_model(&self) -> Model {
+        Model::Storage
+    }
+}
+
+impl<'a> GenerateOtp for Storage<'a> {}
+
+impl From<nitrokey_sys::NK_storage_ProductionTest> for StorageProductionInfo {
+    fn from(data: nitrokey_sys::NK_storage_ProductionTest) -> Self {
+        Self {
+            firmware_version: FirmwareVersion {
+                major: data.FirmwareVersion_au8[0],
+                minor: data.FirmwareVersion_au8[1],
+            },
+            firmware_version_internal: data.FirmwareVersionInternal_u8,
+            serial_number_cpu: data.CPU_CardID_u32,
+            sd_card: SdCardData {
+                serial_number: data.SD_CardID_u32,
+                size: data.SD_Card_Size_u8,
+                manufacturing_year: data.SD_Card_ManufacturingYear_u8,
+                manufacturing_month: data.SD_Card_ManufacturingMonth_u8,
+                oem: data.SD_Card_OEM_u16,
+                manufacturer: data.SD_Card_Manufacturer_u8,
+            },
+        }
+    }
+}
+
+impl From<nitrokey_sys::NK_storage_status> for StorageStatus {
+    fn from(status: nitrokey_sys::NK_storage_status) -> Self {
+        StorageStatus {
+            unencrypted_volume: VolumeStatus {
+                read_only: status.unencrypted_volume_read_only,
+                active: status.unencrypted_volume_active,
+            },
+            encrypted_volume: VolumeStatus {
+                read_only: status.encrypted_volume_read_only,
+                active: status.encrypted_volume_active,
+            },
+            hidden_volume: VolumeStatus {
+                read_only: status.hidden_volume_read_only,
+                active: status.hidden_volume_active,
+            },
+            firmware_version: FirmwareVersion {
+                major: status.firmware_version_major,
+                minor: status.firmware_version_minor,
+            },
+            firmware_locked: status.firmware_locked,
+            serial_number_sd_card: status.serial_number_sd_card,
+            serial_number_smart_card: status.serial_number_smart_card,
+            user_retry_count: status.user_retry_count,
+            admin_retry_count: status.admin_retry_count,
+            new_sd_card_found: status.new_sd_card_found,
+            filled_with_random: status.filled_with_random,
+            stick_initialized: status.stick_initialized,
+        }
+    }
+}
diff --git a/src/device/wrapper.rs b/src/device/wrapper.rs
new file mode 100644
index 0000000..a3a18f9
--- /dev/null
+++ b/src/device/wrapper.rs
@@ -0,0 +1,134 @@
+// Copyright (C) 2018-2019 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: MIT
+
+use crate::device::{Device, Model, Pro, Storage};
+use crate::error::Error;
+use crate::otp::GenerateOtp;
+
+/// A wrapper for a Nitrokey device of unknown type.
+///
+/// Use the [`connect`][] method to obtain a wrapped instance.  The wrapper implements all traits
+/// that are shared between all Nitrokey devices so that the shared functionality can be used
+/// without knowing the type of the underlying device.  If you want to use functionality that is
+/// not available for all devices, you have to extract the device.
+///
+/// # Examples
+///
+/// Authentication with error handling:
+///
+/// ```no_run
+/// use nitrokey::{Authenticate, DeviceWrapper, User};
+/// # use nitrokey::Error;
+///
+/// fn perform_user_task<'a>(device: &User<'a, DeviceWrapper<'a>>) {}
+/// fn perform_other_task(device: &DeviceWrapper) {}
+///
+/// # fn try_main() -> Result<(), Error> {
+/// let mut manager = nitrokey::take()?;
+/// let device = manager.connect()?;
+/// let device = match device.authenticate_user("123456") {
+///     Ok(user) => {
+///         perform_user_task(&user);
+///         user.device()
+///     },
+///     Err((device, err)) => {
+///         eprintln!("Could not authenticate as user: {}", err);
+///         device
+///     },
+/// };
+/// perform_other_task(&device);
+/// #     Ok(())
+/// # }
+/// ```
+///
+/// Device-specific commands:
+///
+/// ```no_run
+/// use nitrokey::{DeviceWrapper, Storage};
+/// # use nitrokey::Error;
+///
+/// fn perform_common_task(device: &DeviceWrapper) {}
+/// fn perform_storage_task(device: &Storage) {}
+///
+/// # fn try_main() -> Result<(), Error> {
+/// let mut manager = nitrokey::take()?;
+/// let device = manager.connect()?;
+/// perform_common_task(&device);
+/// match device {
+///     DeviceWrapper::Storage(storage) => perform_storage_task(&storage),
+///     _ => (),
+/// };
+/// #     Ok(())
+/// # }
+/// ```
+///
+/// [`connect`]: struct.Manager.html#method.connect
+#[derive(Debug)]
+pub enum DeviceWrapper<'a> {
+    /// A Nitrokey Storage device.
+    Storage(Storage<'a>),
+    /// A Nitrokey Pro device.
+    Pro(Pro<'a>),
+}
+
+impl<'a> DeviceWrapper<'a> {
+    fn device(&self) -> &dyn Device<'a> {
+        match *self {
+            DeviceWrapper::Storage(ref storage) => storage,
+            DeviceWrapper::Pro(ref pro) => pro,
+        }
+    }
+
+    fn device_mut(&mut self) -> &mut dyn Device<'a> {
+        match *self {
+            DeviceWrapper::Storage(ref mut storage) => storage,
+            DeviceWrapper::Pro(ref mut pro) => pro,
+        }
+    }
+}
+
+impl<'a> From<Pro<'a>> for DeviceWrapper<'a> {
+    fn from(device: Pro<'a>) -> Self {
+        DeviceWrapper::Pro(device)
+    }
+}
+
+impl<'a> From<Storage<'a>> for DeviceWrapper<'a> {
+    fn from(device: Storage<'a>) -> Self {
+        DeviceWrapper::Storage(device)
+    }
+}
+
+impl<'a> GenerateOtp for DeviceWrapper<'a> {
+    fn get_hotp_slot_name(&self, slot: u8) -> Result<String, Error> {
+        self.device().get_hotp_slot_name(slot)
+    }
+
+    fn get_totp_slot_name(&self, slot: u8) -> Result<String, Error> {
+        self.device().get_totp_slot_name(slot)
+    }
+
+    fn get_hotp_code(&mut self, slot: u8) -> Result<String, Error> {
+        self.device_mut().get_hotp_code(slot)
+    }
+
+    fn get_totp_code(&self, slot: u8) -> Result<String, Error> {
+        self.device().get_totp_code(slot)
+    }
+}
+
+impl<'a> Device<'a> for DeviceWrapper<'a> {
+    fn into_manager(self) -> &'a mut crate::Manager {
+        match self {
+            DeviceWrapper::Pro(dev) => dev.into_manager(),
+            DeviceWrapper::Storage(dev) => dev.into_manager(),
+        }
+    }
+
+    fn get_model(&self) -> Model {
+        match *self {
+            DeviceWrapper::Pro(_) => Model::Pro,
+            DeviceWrapper::Storage(_) => Model::Storage,
+        }
+    }
+}