bitbox03/ui: password stub

diff --git a/src/rust/bitbox03/src/ui.rs b/src/rust/bitbox03/src/ui.rs
index 48ddbf3..405231d 100644
--- a/src/rust/bitbox03/src/ui.rs
+++ b/src/rust/bitbox03/src/ui.rs
@@ -8,6 +8,7 @@ use tracing::info;
 use util::futures::completion;
 
 mod confirm;
+mod enter_string;
 
 const LOGO: &[u8] = include_bytes!("../splash.png");
 
@@ -100,11 +101,14 @@ impl hal::ui::Ui for BitBox03Ui {
 
     async fn enter_string(
         &mut self,
-        _params: &bitbox_hal::ui::EnterStringParams<'_>,
-        _can_cancel: bitbox_hal::ui::CanCancel,
-        _preset: &str,
+        params: &bitbox_hal::ui::EnterStringParams<'_>,
+        can_cancel: bitbox_hal::ui::CanCancel,
+        preset: &str,
     ) -> Result<zeroize::Zeroizing<alloc::string::String>, bitbox_hal::ui::UserAbort> {
-        todo!()
+        self.with_result_screen(|responder| {
+            enter_string::build_enter_string_screen(params, can_cancel, preset, responder)
+        })
+        .await
     }
 
     async fn insert_sdcard(&mut self) -> Result<(), bitbox_hal::ui::UserAbort> {
diff --git a/src/rust/bitbox03/src/ui/enter_string.rs b/src/rust/bitbox03/src/ui/enter_string.rs
new file mode 100644
index 0000000..e58ca38
--- /dev/null
+++ b/src/rust/bitbox03/src/ui/enter_string.rs
@@ -0,0 +1,475 @@
+// SPDX-License-Identifier: Apache-2.0
+
+use alloc::{rc::Rc, string::String};
+
+use bitbox_hal::ui::{CanCancel, EnterStringParams, UserAbort};
+use bitbox_lvgl::{
+    self as lvgl, KeyboardExt, LabelExt, LvAlign, LvButton, LvButtonmatrixCtrl, LvKeyboard,
+    LvKeyboardMapEntry, LvLabel, LvLabelLongMode, LvObj, LvOpacityLevel, LvPart, LvTextarea,
+    ObjExt, TextareaExt,
+};
+use util::futures::completion::Responder;
+
+fn snapshot_text(textarea: &LvTextarea) -> String {
+    textarea
+        .get_text()
+        .map(|text| {
+            text.as_c_str()
+                .to_str()
+                .expect("textarea content must be valid UTF-8")
+                .into()
+        })
+        .unwrap_or_default()
+}
+
+#[derive(Clone, Copy)]
+enum KeyboardMode {
+    LowerCase,
+    UpperCase,
+    Digits,
+    SpecialChars,
+}
+
+impl KeyboardMode {
+    fn next(self, special_chars: bool) -> Self {
+        match self {
+            Self::LowerCase => Self::UpperCase,
+            Self::UpperCase => Self::Digits,
+            Self::Digits => {
+                if special_chars {
+                    Self::SpecialChars
+                } else {
+                    Self::LowerCase
+                }
+            }
+            Self::SpecialChars => Self::LowerCase,
+        }
+    }
+
+    fn switch_label(self, special_chars: bool) -> &'static str {
+        match self {
+            Self::LowerCase => "ABC",
+            Self::UpperCase => "123",
+            Self::Digits => {
+                if special_chars {
+                    "&?+"
+                } else {
+                    "abc"
+                }
+            }
+            Self::SpecialChars => "abc",
+        }
+    }
+
+    fn lvgl_mode(self) -> lvgl::LvKeyboardMode {
+        match self {
+            Self::LowerCase => lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_1,
+            Self::UpperCase => lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_2,
+            Self::Digits => lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_3,
+            Self::SpecialChars => lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_4,
+        }
+    }
+}
+
+const KEY_WIDTH_1: LvButtonmatrixCtrl = LvButtonmatrixCtrl::LV_BUTTONMATRIX_CTRL_WIDTH_1;
+
+const LOWERCASE_MAP: &[LvKeyboardMapEntry] = &[
+    LvKeyboardMapEntry::new(c"a"),
+    LvKeyboardMapEntry::new(c"b"),
+    LvKeyboardMapEntry::new(c"c"),
+    LvKeyboardMapEntry::new(c"d"),
+    LvKeyboardMapEntry::new(c"e"),
+    LvKeyboardMapEntry::new(c"f"),
+    LvKeyboardMapEntry::new(c"g"),
+    LvKeyboardMapEntry::new(c"h"),
+    LvKeyboardMapEntry::new(c"i"),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c"j"),
+    LvKeyboardMapEntry::new(c"k"),
+    LvKeyboardMapEntry::new(c"l"),
+    LvKeyboardMapEntry::new(c"m"),
+    LvKeyboardMapEntry::new(c"n"),
+    LvKeyboardMapEntry::new(c"o"),
+    LvKeyboardMapEntry::new(c"p"),
+    LvKeyboardMapEntry::new(c"q"),
+    LvKeyboardMapEntry::new(c"r"),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c"s"),
+    LvKeyboardMapEntry::new(c"t"),
+    LvKeyboardMapEntry::new(c"u"),
+    LvKeyboardMapEntry::new(c"v"),
+    LvKeyboardMapEntry::new(c"w"),
+    LvKeyboardMapEntry::new(c"x"),
+    LvKeyboardMapEntry::new(c"y"),
+    LvKeyboardMapEntry::new(c"z"),
+    LvKeyboardMapEntry::new(c""),
+];
+
+const UPPERCASE_MAP: &[LvKeyboardMapEntry] = &[
+    LvKeyboardMapEntry::new(c"A"),
+    LvKeyboardMapEntry::new(c"B"),
+    LvKeyboardMapEntry::new(c"C"),
+    LvKeyboardMapEntry::new(c"D"),
+    LvKeyboardMapEntry::new(c"E"),
+    LvKeyboardMapEntry::new(c"F"),
+    LvKeyboardMapEntry::new(c"G"),
+    LvKeyboardMapEntry::new(c"H"),
+    LvKeyboardMapEntry::new(c"I"),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c"J"),
+    LvKeyboardMapEntry::new(c"K"),
+    LvKeyboardMapEntry::new(c"L"),
+    LvKeyboardMapEntry::new(c"M"),
+    LvKeyboardMapEntry::new(c"N"),
+    LvKeyboardMapEntry::new(c"O"),
+    LvKeyboardMapEntry::new(c"P"),
+    LvKeyboardMapEntry::new(c"Q"),
+    LvKeyboardMapEntry::new(c"R"),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c"S"),
+    LvKeyboardMapEntry::new(c"T"),
+    LvKeyboardMapEntry::new(c"U"),
+    LvKeyboardMapEntry::new(c"V"),
+    LvKeyboardMapEntry::new(c"W"),
+    LvKeyboardMapEntry::new(c"X"),
+    LvKeyboardMapEntry::new(c"Y"),
+    LvKeyboardMapEntry::new(c"Z"),
+    LvKeyboardMapEntry::new(c""),
+];
+
+const DIGITS_MAP: &[LvKeyboardMapEntry] = &[
+    LvKeyboardMapEntry::new(c"1"),
+    LvKeyboardMapEntry::new(c"2"),
+    LvKeyboardMapEntry::new(c"3"),
+    LvKeyboardMapEntry::new(c"4"),
+    LvKeyboardMapEntry::new(c"5"),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c"6"),
+    LvKeyboardMapEntry::new(c"7"),
+    LvKeyboardMapEntry::new(c"8"),
+    LvKeyboardMapEntry::new(c"9"),
+    LvKeyboardMapEntry::new(c"0"),
+    LvKeyboardMapEntry::new(c""),
+];
+
+const SPECIAL_CHARS_MAP: &[LvKeyboardMapEntry] = &[
+    LvKeyboardMapEntry::new(c" "),
+    LvKeyboardMapEntry::new(c"!"),
+    LvKeyboardMapEntry::new(c"\""),
+    LvKeyboardMapEntry::new(c"#"),
+    LvKeyboardMapEntry::new(c"$"),
+    LvKeyboardMapEntry::new(c"%"),
+    LvKeyboardMapEntry::new(c"&"),
+    LvKeyboardMapEntry::new(c"'"),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c"("),
+    LvKeyboardMapEntry::new(c")"),
+    LvKeyboardMapEntry::new(c"*"),
+    LvKeyboardMapEntry::new(c"+"),
+    LvKeyboardMapEntry::new(c","),
+    LvKeyboardMapEntry::new(c"-"),
+    LvKeyboardMapEntry::new(c"."),
+    LvKeyboardMapEntry::new(c"/"),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c":"),
+    LvKeyboardMapEntry::new(c";"),
+    LvKeyboardMapEntry::new(c"<"),
+    LvKeyboardMapEntry::new(c"="),
+    LvKeyboardMapEntry::new(c">"),
+    LvKeyboardMapEntry::new(c"?"),
+    LvKeyboardMapEntry::new(c"^"),
+    LvKeyboardMapEntry::new(c"["),
+    LvKeyboardMapEntry::new(c"\n"),
+    LvKeyboardMapEntry::new(c"\\"),
+    LvKeyboardMapEntry::new(c"]"),
+    LvKeyboardMapEntry::new(c"@"),
+    LvKeyboardMapEntry::new(c"_"),
+    LvKeyboardMapEntry::new(c"{"),
+    LvKeyboardMapEntry::new(c"|"),
+    LvKeyboardMapEntry::new(c"}"),
+    LvKeyboardMapEntry::new(c""),
+];
+
+const LOWERCASE_CTRL_MAP: &[LvButtonmatrixCtrl] = &[KEY_WIDTH_1; 26];
+const UPPERCASE_CTRL_MAP: &[LvButtonmatrixCtrl] = &[KEY_WIDTH_1; 26];
+const DIGITS_CTRL_MAP: &[LvButtonmatrixCtrl] = &[KEY_WIDTH_1; 10];
+const SPECIAL_CHARS_CTRL_MAP: &[LvButtonmatrixCtrl] = &[KEY_WIDTH_1; 31];
+
+fn configure_keyboard_maps(keyboard: &LvKeyboard) {
+    keyboard.set_map(
+        lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_1,
+        LOWERCASE_MAP,
+        LOWERCASE_CTRL_MAP,
+    );
+    keyboard.set_map(
+        lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_2,
+        UPPERCASE_MAP,
+        UPPERCASE_CTRL_MAP,
+    );
+    keyboard.set_map(
+        lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_3,
+        DIGITS_MAP,
+        DIGITS_CTRL_MAP,
+    );
+    keyboard.set_map(
+        lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_USER_4,
+        SPECIAL_CHARS_MAP,
+        SPECIAL_CHARS_CTRL_MAP,
+    );
+}
+
+fn add_button<F>(
+    parent: &LvObj,
+    width: i32,
+    height: i32,
+    label: &str,
+    primary: bool,
+    longtouch: bool,
+    cb: F,
+) where
+    F: FnMut() + 'static,
+{
+    let button = LvButton::new(parent).unwrap();
+    button.set_size(width, height);
+    button.set_style_bg_color(
+        if primary {
+            lvgl::color::white()
+        } else {
+            lvgl::color::hex(0x30333a)
+        },
+        0,
+    );
+    button.set_style_bg_opa(LvOpacityLevel::LV_OPA_COVER as u8, 0);
+    button.set_style_border_width(2, 0);
+    button.set_style_border_color(
+        if primary {
+            lvgl::color::black()
+        } else {
+            lvgl::color::white()
+        },
+        0,
+    );
+    if longtouch {
+        button
+            .add_event_cb(lvgl::LvEventCode::LV_EVENT_LONG_PRESSED, cb)
+            .expect("failed to register long press callback");
+    } else {
+        button
+            .add_click_cb(cb)
+            .expect("failed to register click callback");
+    }
+
+    let button_label = LvLabel::new(&button).unwrap();
+    button_label.set_text(label).unwrap();
+    button_label.set_style_text_font(
+        lvgl::fonts::INTER_BOLD_32,
+        lvgl::LvState::LV_STATE_DEFAULT as u32,
+    );
+    button_label.set_style_text_color(
+        if primary {
+            lvgl::color::black()
+        } else {
+            lvgl::color::white()
+        },
+        0,
+    );
+    button_label.align(LvAlign::LV_ALIGN_CENTER, 0, 0);
+}
+
+pub(super) fn build_enter_string_screen(
+    params: &EnterStringParams<'_>,
+    can_cancel: CanCancel,
+    preset: &str,
+    responder: Responder<Result<zeroize::Zeroizing<String>, UserAbort>>,
+) -> LvObj {
+    let screen = LvObj::new().unwrap();
+    screen.set_layout(lvgl::LvLayout::LV_LAYOUT_FLEX);
+    screen.set_flex_flow(lvgl::LvFlexFlow::LV_FLEX_FLOW_COLUMN);
+    screen.set_style_bg_color(lvgl::color::black(), 0);
+    screen.set_style_text_color(lvgl::color::white(), 0);
+    screen.set_style_pad_top(40, 0);
+    screen.set_style_pad_right(50, 0);
+    screen.set_style_pad_bottom(32, 0);
+    screen.set_style_pad_left(50, 0);
+    screen.set_style_pad_row(20, 0);
+
+    let title = LvLabel::new(&screen).unwrap();
+    title.set_width(380);
+    title.set_long_mode(LvLabelLongMode::LV_LABEL_LONG_MODE_WRAP);
+    title.set_text(params.title).unwrap();
+    title.set_style_text_font(
+        lvgl::fonts::INTER_BOLD_48,
+        lvgl::LvState::LV_STATE_DEFAULT as u32,
+    );
+
+    let textarea = LvTextarea::new(&screen).unwrap();
+    textarea.set_size(380, 72);
+    textarea.set_one_line(true);
+    textarea
+        .set_text(preset)
+        .expect("preset must not contain NUL");
+    textarea.set_style_bg_color(lvgl::color::hex(0x111317), 0);
+    textarea.set_style_bg_opa(LvOpacityLevel::LV_OPA_COVER as u8, 0);
+    textarea.set_style_border_width(2, 0);
+    textarea.set_style_border_color(lvgl::color::white(), 0);
+    textarea.set_style_radius(0, 0);
+    textarea.set_style_pad_left(20, 0);
+    textarea.set_style_pad_right(20, 0);
+    textarea.set_style_pad_top(16, 0);
+    textarea.set_style_pad_bottom(16, 0);
+    textarea.set_style_text_color(lvgl::color::white(), 0);
+    textarea.set_style_text_font(
+        lvgl::fonts::INTER_REGULAR_32,
+        lvgl::LvState::LV_STATE_DEFAULT as u32,
+    );
+    if params.hide {
+        textarea.set_password_mode(true);
+        textarea
+            .set_password_bullet("*")
+            .expect("valid password bullet");
+        textarea.set_password_show_time(0);
+    }
+
+    if params.number_input {
+        textarea.set_accepted_chars(Some(c"0123456789"));
+    }
+
+    let textarea = Rc::new(textarea);
+
+    let keyboard = LvKeyboard::new(&screen).unwrap();
+    keyboard.set_width(380);
+    keyboard.set_height(260);
+    keyboard.set_style_flex_grow(1, 0);
+    keyboard.set_style_margin_top(4, 0);
+    keyboard.set_popovers(false);
+    let show_keyboard_switch = params.wordlist.is_none() && !params.number_input;
+    let initial_keyboard_mode = if params.number_input {
+        None
+    } else if params.default_to_digits && params.wordlist.is_none() {
+        Some(KeyboardMode::Digits)
+    } else {
+        Some(KeyboardMode::LowerCase)
+    };
+    if let Some(mode) = initial_keyboard_mode {
+        configure_keyboard_maps(&keyboard);
+        keyboard.set_mode(mode.lvgl_mode());
+    } else {
+        keyboard.set_mode(lvgl::LvKeyboardMode::LV_KEYBOARD_MODE_NUMBER);
+    }
+    // Safe because the textarea and keyboard are siblings on the same screen and remain alive
+    // until the whole screen is popped.
+    unsafe { keyboard.set_textarea(Some(textarea.as_ref())) };
+
+    let input_controls = LvObj::with_parent(&screen).unwrap();
+    input_controls.set_width(380);
+    input_controls.set_height(56);
+    input_controls.set_layout(lvgl::LvLayout::LV_LAYOUT_FLEX);
+    input_controls.set_flex_flow(lvgl::LvFlexFlow::LV_FLEX_FLOW_ROW);
+    input_controls.set_style_pad_top(0, 0);
+    input_controls.set_style_pad_bottom(0, 0);
+    input_controls.set_style_pad_left(0, 0);
+    input_controls.set_style_pad_right(0, 0);
+    input_controls.set_style_pad_column(12, 0);
+    input_controls.set_style_border_width(0, 0);
+    input_controls.set_style_bg_opa(
+        LvOpacityLevel::LV_OPA_TRANSP as u8,
+        LvPart::LV_PART_MAIN as u32,
+    );
+
+    if show_keyboard_switch {
+        let mut keyboard_mode = initial_keyboard_mode.expect("keyboard switch requires mode");
+        let allow_special_chars = params.special_chars;
+        let switch_button = LvButton::new(&input_controls).unwrap();
+        switch_button.set_size(184, 56);
+        switch_button.set_style_bg_color(lvgl::color::hex(0x30333a), 0);
+        switch_button.set_style_bg_opa(LvOpacityLevel::LV_OPA_COVER as u8, 0);
+        switch_button.set_style_border_width(2, 0);
+        switch_button.set_style_border_color(lvgl::color::white(), 0);
+        let switch_button_label = LvLabel::new(&switch_button).unwrap();
+        switch_button_label
+            .set_text(keyboard_mode.switch_label(allow_special_chars))
+            .unwrap();
+        switch_button_label.set_style_text_font(
+            lvgl::fonts::INTER_BOLD_32,
+            lvgl::LvState::LV_STATE_DEFAULT as u32,
+        );
+        switch_button_label.set_style_text_color(lvgl::color::white(), 0);
+        switch_button_label.align(LvAlign::LV_ALIGN_CENTER, 0, 0);
+        switch_button
+            .add_click_cb(move || {
+                keyboard_mode = keyboard_mode.next(allow_special_chars);
+                keyboard.set_mode(keyboard_mode.lvgl_mode());
+                switch_button_label
+                    .set_text(keyboard_mode.switch_label(allow_special_chars))
+                    .expect("valid switch label");
+            })
+            .expect("failed to register keyboard switch callback");
+    }
+
+    let delete_textarea = Rc::clone(&textarea);
+    add_button(
+        &input_controls,
+        if show_keyboard_switch { 184 } else { 380 },
+        56,
+        "Delete",
+        false,
+        false,
+        move || delete_textarea.delete_char(),
+    );
+
+    let actions = LvObj::with_parent(&screen).unwrap();
+    actions.set_width(380);
+    actions.set_height(72);
+    actions.set_layout(lvgl::LvLayout::LV_LAYOUT_FLEX);
+    actions.set_flex_flow(lvgl::LvFlexFlow::LV_FLEX_FLOW_ROW);
+    actions.set_style_pad_top(0, 0);
+    actions.set_style_pad_bottom(0, 0);
+    actions.set_style_pad_left(0, 0);
+    actions.set_style_pad_right(0, 0);
+    actions.set_style_pad_column(20, 0);
+    actions.set_style_margin_top(8, 0);
+    actions.set_style_border_width(0, 0);
+    actions.set_style_bg_opa(
+        LvOpacityLevel::LV_OPA_TRANSP as u8,
+        LvPart::LV_PART_MAIN as u32,
+    );
+
+    if matches!(can_cancel, CanCancel::Yes) {
+        let cancel_label = if params.cancel_is_backbutton {
+            "Back"
+        } else {
+            "Cancel"
+        };
+        let reject_responder = responder.clone();
+        add_button(&actions, 180, 72, cancel_label, false, false, move || {
+            reject_responder.resolve(Err(UserAbort));
+        });
+    }
+
+    let accept_label = if params.longtouch && matches!(can_cancel, CanCancel::No) {
+        "Hold to confirm"
+    } else if params.longtouch {
+        "Hold"
+    } else {
+        "Confirm"
+    };
+    add_button(
+        &actions,
+        if matches!(can_cancel, CanCancel::Yes) {
+            180
+        } else {
+            380
+        },
+        72,
+        accept_label,
+        true,
+        params.longtouch,
+        move || {
+            responder.resolve(Ok(zeroize::Zeroizing::new(snapshot_text(
+                textarea.as_ref(),
+            ))));
+        },
+    );
+
+    screen
+}