key-logger

This is a simple implementation of a cross-platform key logger in Go.

Supported Platforms

• Windows

  Implemented through the SetWindowsHookExW(WH_KEYBOARD_LL) API.

• Linux

  Implemented through the /dev/input/event/ filesystem API.

  (See dev-input for more information.)

Important

On Linux, root is required to read keyboard events.

Usage

go get github.com/nathan-fiscaletti/key-logger

Raw Keyboard Events

Raw keyboard events will include both the key pressed and the key released events.

View Documentation: ./cmd/example/raw/main.go

Tip

Run this example with: go run ./cmd/example/raw or use the built in VSCode Run Configuration.

package main

import (
	"fmt"

	"github.com/nathan-fiscaletti/key-logger/pkg/key"
	"github.com/nathan-fiscaletti/key-logger/pkg/keyboard"

	"context"
)

func main() {
	ctx := context.Background()
	ctx, cancel := context.WithCancel(ctx)
	kb := keyboard.New()

	err := kb.Listen(ctx, func(event keyboard.Event) {
		fmt.Printf("Key: %s, Event: %s\n", event.Key.Name, event.EventType)

		if event.Key.Equals(key.Escape) {
			cancel()
		}
	})

	if err != nil {
		fmt.Printf("Error listening for keyboard events: %v\n", err)
		return
	}

	fmt.Println("Listening for keyboard events...")
	<-ctx.Done()
}

Key Listener

The key listener will only include the key released events, but each event will also include a list of modifier keys that were pressed at the time of the event.

View Documentation: ./cmd/example/keylistener/main.go

You can use key.IsModifierKey to check if a key is a modifier key.

Tip

Run this example with: go run ./cmd/example/keylistener or use the built in VSCode Run Configuration.

package main

import (
	"fmt"
	"log"

	"github.com/nathan-fiscaletti/key-logger/pkg/key"
	"github.com/nathan-fiscaletti/key-logger/pkg/keyboard"
	"github.com/nathan-fiscaletti/key-logger/pkg/listener"
	"github.com/samber/lo"

	"context"
)

func main() {
	ctx := context.Background()
	ctx, cancel := context.WithCancel(ctx)

	kb := keyboard.New()
	kl := listener.New(kb)

	err := kl.Listen(ctx, func(event listener.KeyEvent) {
		fmt.Printf(
			"Key: %v, Modifiers: %v\n",
			event.Key.Name,
			lo.Map(
				lo.Filter(event.Modifiers, func(k key.Key, _ int) bool {
					return key.IsModifierKey(k)
				}),
				func(k key.Key, _ int) string { return k.Name },
			),
		)

		if event.Key.Equals(key.Escape) {
			cancel()
		}
	})

	if err != nil {
		log.Fatal("Error listening for keyboard events: %v\n", err)
		return
	}

	fmt.Println("Listening for keyboard events...")
	<-ctx.Done()
}