diff --git a/libs/input/rust/keyboard_classifier.rs b/libs/input/rust/keyboard_classifier.rs
index bd3a51c..1063fac 100644
--- a/libs/input/rust/keyboard_classifier.rs
+++ b/libs/input/rust/keyboard_classifier.rs
@@ -17,14 +17,39 @@
 //! Contains the KeyboardClassifier, that tries to identify whether an Input device is an
 //! alphabetic or non-alphabetic keyboard. It also tracks the KeyEvents produced by the device
 //! in order to verify/change the inferred keyboard type.
+//!
+//! Initial classification:
+//! - If DeviceClass includes Dpad, Touch, Cursor, MultiTouch, ExternalStylus, Touchpad, Dpad,
+//!   Gamepad, Switch, Joystick, RotaryEncoder => KeyboardType::NonAlphabetic
+//! - Otherwise if DeviceClass has Keyboard and not AlphabeticKey => KeyboardType::NonAlphabetic
+//! - Otherwise if DeviceClass has both Keyboard and AlphabeticKey => KeyboardType::Alphabetic
+//!
+//! On process keys:
+//! - If KeyboardType::NonAlphabetic and we receive alphabetic key event, then change type to
+//!   KeyboardType::Alphabetic. Once changed, no further changes. (i.e. verified = true)
+//! - TODO(b/263559234): If KeyboardType::Alphabetic and we don't receive any alphabetic key event
+//!    across multiple device connections in a time period, then change type to
+//!    KeyboardType::NonAlphabetic. Once changed, it can still change back to Alphabetic
+//!    (i.e. verified = false).
+//!
+//! TODO(b/263559234): Data store implementation to store information about past classification
 
 use crate::input::{DeviceId, InputDevice, KeyboardType};
-use crate::ModifierState;
+use crate::{DeviceClass, ModifierState};
+use std::collections::HashMap;
 
 /// The KeyboardClassifier is used to classify a keyboard device into non-keyboard, alphabetic
 /// keyboard or non-alphabetic keyboard
 #[derive(Default)]
-pub struct KeyboardClassifier {}
+pub struct KeyboardClassifier {
+    device_map: HashMap<DeviceId, KeyboardInfo>,
+}
+
+struct KeyboardInfo {
+    _device: InputDevice,
+    keyboard_type: KeyboardType,
+    is_finalized: bool,
+}
 
 impl KeyboardClassifier {
     /// Create a new KeyboardClassifier
@@ -33,30 +58,288 @@
     }
 
     /// Adds keyboard to KeyboardClassifier
-    pub fn notify_keyboard_changed(&mut self, _device: InputDevice) {
-        // TODO(b/263559234): Implement method
+    pub fn notify_keyboard_changed(&mut self, device: InputDevice) {
+        let (keyboard_type, is_finalized) = self.classify_keyboard(&device);
+        self.device_map.insert(
+            device.device_id,
+            KeyboardInfo { _device: device, keyboard_type, is_finalized },
+        );
     }
 
     /// Get keyboard type for a tracked keyboard in KeyboardClassifier
-    pub fn get_keyboard_type(&self, _device_id: DeviceId) -> KeyboardType {
-        // TODO(b/263559234): Implement method
-        KeyboardType::None
+    pub fn get_keyboard_type(&self, device_id: DeviceId) -> KeyboardType {
+        return if let Some(keyboard) = self.device_map.get(&device_id) {
+            keyboard.keyboard_type
+        } else {
+            KeyboardType::None
+        };
     }
 
     /// Tells if keyboard type classification is finalized. Once finalized the classification can't
     /// change until device is reconnected again.
-    pub fn is_finalized(&self, _device_id: DeviceId) -> bool {
-        // TODO(b/263559234): Implement method
-        false
+    ///
+    /// Finalized devices are either "alphabetic" keyboards or keyboards in blocklist or
+    /// allowlist that are explicitly categorized and won't change with future key events
+    pub fn is_finalized(&self, device_id: DeviceId) -> bool {
+        return if let Some(keyboard) = self.device_map.get(&device_id) {
+            keyboard.is_finalized
+        } else {
+            false
+        };
     }
 
     /// Process a key event and change keyboard type if required.
+    /// - If any key event occurs, the keyboard type will change from None to NonAlphabetic
+    /// - If an alphabetic key occurs, the keyboard type will change to Alphabetic
     pub fn process_key(
         &mut self,
-        _device_id: DeviceId,
-        _evdev_code: i32,
-        _modifier_state: ModifierState,
+        device_id: DeviceId,
+        evdev_code: i32,
+        modifier_state: ModifierState,
     ) {
-        // TODO(b/263559234): Implement method
+        if let Some(keyboard) = self.device_map.get_mut(&device_id) {
+            // Ignore all key events with modifier state since they can be macro shortcuts used by
+            // some non-keyboard peripherals like TV remotes, game controllers, etc.
+            if modifier_state.bits() != 0 {
+                return;
+            }
+            if Self::is_alphabetic_key(&evdev_code) {
+                keyboard.keyboard_type = KeyboardType::Alphabetic;
+                keyboard.is_finalized = true;
+            }
+        }
+    }
+
+    fn classify_keyboard(&self, device: &InputDevice) -> (KeyboardType, bool) {
+        // This should never happen but having keyboard device class is necessary to be classified
+        // as any type of keyboard.
+        if !device.classes.contains(DeviceClass::Keyboard) {
+            return (KeyboardType::None, true);
+        }
+        // Normal classification for internal and virtual keyboards
+        if !device.classes.contains(DeviceClass::External)
+            || device.classes.contains(DeviceClass::Virtual)
+        {
+            return if device.classes.contains(DeviceClass::AlphabeticKey) {
+                (KeyboardType::Alphabetic, true)
+            } else {
+                (KeyboardType::NonAlphabetic, true)
+            };
+        }
+        // Any composite device with multiple device classes should be categorized as non-alphabetic
+        // keyboard initially
+        if device.classes.contains(DeviceClass::Touch)
+            || device.classes.contains(DeviceClass::Cursor)
+            || device.classes.contains(DeviceClass::MultiTouch)
+            || device.classes.contains(DeviceClass::ExternalStylus)
+            || device.classes.contains(DeviceClass::Touchpad)
+            || device.classes.contains(DeviceClass::Dpad)
+            || device.classes.contains(DeviceClass::Gamepad)
+            || device.classes.contains(DeviceClass::Switch)
+            || device.classes.contains(DeviceClass::Joystick)
+            || device.classes.contains(DeviceClass::RotaryEncoder)
+        {
+            // If categorized as NonAlphabetic and no device class AlphabeticKey reported by the
+            // kernel, we no longer need to process key events to verify.
+            return (
+                KeyboardType::NonAlphabetic,
+                !device.classes.contains(DeviceClass::AlphabeticKey),
+            );
+        }
+        // Only devices with "Keyboard" and "AlphabeticKey" should be classified as full keyboard
+        if device.classes.contains(DeviceClass::AlphabeticKey) {
+            (KeyboardType::Alphabetic, true)
+        } else {
+            // If categorized as NonAlphabetic and no device class AlphabeticKey reported by the
+            // kernel, we no longer need to process key events to verify.
+            (KeyboardType::NonAlphabetic, true)
+        }
+    }
+
+    fn is_alphabetic_key(evdev_code: &i32) -> bool {
+        // Keyboard alphabetic row 1 (Q W E R T Y U I O P [ ])
+        (16..=27).contains(evdev_code)
+            // Keyboard alphabetic row 2 (A S D F G H J K L ; ' `)
+            || (30..=41).contains(evdev_code)
+            // Keyboard alphabetic row 3 (\ Z X C V B N M , . /)
+            || (43..=53).contains(evdev_code)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::input::{DeviceId, InputDevice, KeyboardType};
+    use crate::keyboard_classifier::KeyboardClassifier;
+    use crate::{DeviceClass, ModifierState, RustInputDeviceIdentifier};
+
+    static DEVICE_ID: DeviceId = DeviceId(1);
+    static KEY_A: i32 = 30;
+    static KEY_1: i32 = 2;
+
+    #[test]
+    fn classify_external_alphabetic_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard | DeviceClass::AlphabeticKey | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::Alphabetic);
+        assert!(classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn classify_external_non_alphabetic_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier
+            .notify_keyboard_changed(create_device(DeviceClass::Keyboard | DeviceClass::External));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn classify_mouse_pretending_as_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Cursor
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn classify_touchpad_pretending_as_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Touchpad
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn classify_stylus_pretending_as_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::ExternalStylus
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn classify_dpad_pretending_as_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Dpad
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn classify_joystick_pretending_as_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Joystick
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn classify_gamepad_pretending_as_keyboard() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Gamepad
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn reclassify_keyboard_on_alphabetic_key_event() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Dpad
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+
+        // on alphabetic key event
+        classifier.process_key(DEVICE_ID, KEY_A, ModifierState::None);
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::Alphabetic);
+        assert!(classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn dont_reclassify_keyboard_on_non_alphabetic_key_event() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Dpad
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+
+        // on number key event
+        classifier.process_key(DEVICE_ID, KEY_1, ModifierState::None);
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    #[test]
+    fn dont_reclassify_keyboard_on_alphabetic_key_event_with_modifiers() {
+        let mut classifier = KeyboardClassifier::new();
+        classifier.notify_keyboard_changed(create_device(
+            DeviceClass::Keyboard
+                | DeviceClass::Dpad
+                | DeviceClass::AlphabeticKey
+                | DeviceClass::External,
+        ));
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+
+        classifier.process_key(DEVICE_ID, KEY_A, ModifierState::CtrlOn);
+        assert_eq!(classifier.get_keyboard_type(DEVICE_ID), KeyboardType::NonAlphabetic);
+        assert!(!classifier.is_finalized(DEVICE_ID));
+    }
+
+    fn create_device(classes: DeviceClass) -> InputDevice {
+        InputDevice {
+            device_id: DEVICE_ID,
+            identifier: RustInputDeviceIdentifier {
+                name: "test_device".to_string(),
+                location: "location".to_string(),
+                unique_id: "unique_id".to_string(),
+                bus: 123,
+                vendor: 234,
+                product: 345,
+                version: 567,
+                descriptor: "descriptor".to_string(),
+            },
+            classes,
+        }
     }
 }