keyfork-{shard,prompt}: add Yes/No prompt for verifying QR codes

crates/keyfork-shard/src/lib.rs

@@ -23,7 +23,7 @@ use keyfork_prompt::{
         mnemonic::{MnemonicSetValidator, MnemonicValidator, WordLength},
         Validator,
     },
-    Message as PromptMessage, PromptHandler,
+    Message as PromptMessage, PromptHandler, YesNo,
 };
 use sha2::{Digest, Sha256};
 use x25519_dalek::{EphemeralSecret, PublicKey};
@@ -300,9 +300,19 @@ pub trait Format {
                     let small_mnemonic = Mnemonic::from_raw_bytes(small_sum);
 
                     let mut prompt = prompt.lock().expect(bug!(POISONED_MUTEX));
-                    prompt.prompt_message(PromptMessage::Text(format!(
+                    let question =
-                        "Is THIS your card???? If not, press ctrl+c!: {small_mnemonic}"
+                        format!("Do these words match the expected words? {small_mnemonic}");
-                    )))?;
+                    let response = keyfork_prompt::prompt_choice(
+                        &mut **prompt,
+                        &question,
+                        &[YesNo::No, YesNo::Yes],
+                    )?;
+                    if response == YesNo::No {
+                        prompt.prompt_message(PromptMessage::Text(String::from(
+                            "Could not establish secure channel, exiting.",
+                        )))?;
+                        std::process::exit(1);
+                    }
 
                     pubkey_data = Some(data);
                     break;

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

@@ -83,6 +83,34 @@ impl<T: Choice> Choice for &T {
     }
 }
 
+/// A Yes/No Choice.
+#[derive(PartialEq, Eq, Clone, Copy)]
+pub enum YesNo {
+    /// Yes.
+    Yes,
+
+    /// No.
+    No,
+}
+
+impl std::fmt::Display for YesNo {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            YesNo::Yes => f.write_str("Yes"),
+            YesNo::No => f.write_str("No"),
+        }
+    }
+}
+
+impl Choice for YesNo {
+    fn identifier(&self) -> Option<char> {
+        match self {
+            YesNo::Yes => Some('y'),
+            YesNo::No => Some('n'),
+        }
+    }
+}
+
 #[doc(hidden)]
 pub type BoxResult = std::result::Result<(), Box<dyn std::error::Error>>;