Add basic usage examples

This patch adds two basic usage examples:  listing and connecting to
Nitrokey devices, and generating a one-time password.

2 files changed, 69 insertions, 0 deletions

diff --git a/examples/list-devices.rs b/examples/list-devices.rs
new file mode 100644
index 0000000..9c14533
--- /dev/null
+++ b/examples/list-devices.rs
@@ -0,0 +1,26 @@
+// Copyright (C) 2020 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: CC-0
+
+//! Enumerates all connected Nitrokey devices and prints some information about them.
+
+use nitrokey::Device as _;
+
+fn main() -> Result<(), nitrokey::Error> {
+    let mut manager = nitrokey::take()?;
+    let device_infos = nitrokey::list_devices()?;
+    if device_infos.is_empty() {
+        println!("No Nitrokey device found");
+    } else {
+        println!("path\t\tmodel\tfirmware version\tserial number");
+        for device_info in device_infos {
+            let device = manager.connect_path(device_info.path.clone())?;
+            let model = device.get_model();
+            let status = device.get_status()?;
+            println!(
+                "{}\t{}\t{}\t\t\t{:08x}",
+                device_info.path, model, status.firmware_version, status.serial_number
+            );
+        }
+    }
+    Ok(())
+}
diff --git a/examples/otp.rs b/examples/otp.rs
new file mode 100644
index 0000000..819de28
--- /dev/null
+++ b/examples/otp.rs
@@ -0,0 +1,43 @@
+// Copyright (C) 2020 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: CC-0
+
+//! Connects to a Nitrokey device, configures an TOTP slot and generates a one-time password from
+//! it.
+
+use std::time;
+
+use nitrokey::{Authenticate, ConfigureOtp, Device, GenerateOtp};
+
+fn main() -> Result<(), nitrokey::Error> {
+    let mut manager = nitrokey::take()?;
+    let device = manager.connect()?;
+
+    // Configure the OTP slot (requires admin PIN)
+    let data = nitrokey::OtpSlotData::new(
+        1,
+        "test",
+        "3132333435363738393031323334353637383930",
+        nitrokey::OtpMode::SixDigits,
+    );
+    let mut admin = device.authenticate_admin("12345678")?;
+    admin.write_totp_slot(data, 30)?;
+    let mut device = admin.device();
+
+    // Set the time for the OTP generation
+    let time = time::SystemTime::now()
+        .duration_since(time::UNIX_EPOCH)
+        .expect("Invalid system time");
+    device.set_time(time.as_secs(), true)?;
+
+    // Generate a one-time password -- depending on the configuration, we have to set the user PIN
+    let config = device.get_config()?;
+    let otp = if config.user_password {
+        let user = device.authenticate_user("123456")?;
+        user.get_totp_code(1)
+    } else {
+        device.get_totp_code(1)
+    }?;
+    println!("Generated OTP code: {}", otp);
+
+    Ok(())
+}