keyfork: improve prompt UX of `wizard generate-shard-secret`

crates/keyfork/src/cli/wizard.rs

@@ -1,6 +1,6 @@
 use super::Keyfork;
 use clap::{Parser, Subcommand};
-use std::{collections::HashSet, io::IsTerminal, path::PathBuf, fs::OpenOptions};
+use std::{collections::HashSet, fs::OpenOptions, io::IsTerminal, path::PathBuf};
 
 use card_backend_pcsc::PcscBackend;
 use openpgp_card_sequoia::{state::Open, types::KeyType, Card};
@@ -56,6 +56,7 @@ fn factory_reset_current_card(
     user_pin: &str,
     admin_pin: &str,
     cert: &Cert,
+    card_backend: PcscBackend,
 ) -> Result<()> {
     let policy = openpgp::policy::NullPolicy::new();
     let valid_cert = cert.with_policy(&policy, None)?;
@@ -77,8 +78,7 @@ fn factory_reset_current_card(
         .secret()
         .next()
         .expect("no authentication key found");
-    if let Some(current_backend) = PcscBackend::cards(None)?.next().transpose()? {
-        let mut card = Card::<Open>::new(current_backend)?;
+    let mut card = Card::<Open>::new(card_backend)?;
     let mut transaction = card.transaction()?;
     let application_identifier = transaction.application_identifier()?.ident();
     if seen_cards.contains(&application_identifier) {
@@ -94,13 +94,15 @@ fn factory_reset_current_card(
     admin.upload_key(authentication_key, KeyType::Authentication, None)?;
     transaction.change_user_pin("123456", user_pin)?;
     transaction.change_admin_pin("12345678", admin_pin)?;
-    } else {
-        panic!("No smart card found");
-    }
     Ok(())
 }
 
-fn generate_shard_secret(threshold: u8, max: u8, keys_per_shard: u8, output_file: &Option<PathBuf>) -> Result<()> {
+fn generate_shard_secret(
+    threshold: u8,
+    max: u8,
+    keys_per_shard: u8,
+    output_file: &Option<PathBuf>,
+) -> Result<()> {
     let seed = keyfork_entropy::generate_entropy_of_size(256 / 8)?;
     let mut pm = Terminal::new(std::io::stdin(), std::io::stderr())?;
     let mut certs = vec![];
@@ -128,10 +130,19 @@ fn generate_shard_secret(threshold: u8, max: u8, keys_per_shard: u8, output_file
         let cert = derive_key(&seed, index)?;
         for i in 0..keys_per_shard {
             pm.prompt_message(Message::Text(format!(
-                "Please insert key #{} for user #{}",
+                "Please remove all keys and insert key #{} for user #{}",
                 i + 1,
                 index + 1,
             )))?;
+            let card_backend = loop {
+                if let Some(c) = PcscBackend::cards(None)?.next().transpose()? {
+                    break c;
+                }
+                pm.prompt_message(Message::Text(
+                    "No smart card was found. Please plug in a smart card and press enter"
+                        .to_string(),
+                ))?;
+            };
             let user_pin = pm.prompt_validated_passphrase(
                 "Please enter the new smartcard User PIN: ",
                 3,
@@ -142,7 +153,13 @@ fn generate_shard_secret(threshold: u8, max: u8, keys_per_shard: u8, output_file
                 3,
                 &admin_pin_validator,
             )?;
-            factory_reset_current_card(&mut seen_cards, user_pin.trim(), admin_pin.trim(), &cert)?;
+            factory_reset_current_card(
+                &mut seen_cards,
+                user_pin.trim(),
+                admin_pin.trim(),
+                &cert,
+                card_backend,
+            )?;
         }
         certs.push(cert);
     }

crates/util/keyfork-prompt/src/lib.rs

@@ -21,6 +21,10 @@ pub enum Error {
     #[error("Validation of the input failed after {0} retries (last error: {1})")]
     Validation(u8, String),
 
+    /// A ctrl-c interrupt was caught by the handler.
+    #[error("User pressed ctrl-c, terminating the session")]
+    CtrlC,
+
     /// An error occurred while interacting with a terminal.
     #[error("IO Error: {0}")]
     IO(#[from] std::io::Error),

crates/util/keyfork-prompt/src/terminal.rs

@@ -269,6 +269,9 @@ impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + As
                             input.push(' ');
                         }
                     }
+                    KeyCode::Char('c') if k.modifiers.contains(KeyModifiers::CONTROL) => {
+                        return Err(Error::CtrlC);
+                    }
                     KeyCode::Char(' ') => {
                         if !input.chars().next_back().is_some_and(char::is_whitespace) {
                             input.push(' ');
@@ -410,6 +413,9 @@ impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + As
                                 .flush()?;
                         }
                     }
+                    KeyCode::Char('c') if k.modifiers.contains(KeyModifiers::CONTROL) => {
+                        return Err(Error::CtrlC);
+                    }
                     KeyCode::Char(c) => {
                         if prefix_length + passphrase.len() < (cols - 1) as usize {
                             terminal.queue(Print("*"))?.flush()?;
@@ -485,6 +491,9 @@ impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + As
             #[allow(clippy::single_match)]
             match read()? {
                 Event::Key(k) => match k.code {
+                    KeyCode::Char('c') if k.modifiers.contains(KeyModifiers::CONTROL) => {
+                        return Err(Error::CtrlC);
+                    }
                     KeyCode::Enter | KeyCode::Char(' ' | 'q') => break,
                     _ => (),
                 },