feat: init version

main.go

@@ -0,0 +1,157 @@
+package main
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/hex"
+	"fmt"
+	"os"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/app"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/dialog"
+	"fyne.io/fyne/v2/widget"
+)
+
+const (
+	AlgorithmAes256Gcm = "aes-256-gcm"
+	Title              = "Secure Editor"
+)
+
+func decrypt(ciphertext, key, nonce []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+	return plaintext, nil
+}
+
+func encrypt(plaintext, key, nonce []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	ciphertext := aesgcm.Seal(nil, nonce, plaintext, nil)
+	return ciphertext, nil
+}
+
+func writeFilePreserveMode(filename string, data []byte) error {
+	fi, err := os.Stat(filename)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return os.WriteFile(filename, data, 0666)
+		}
+		return err
+	}
+
+	err = os.WriteFile(filename, data, 0666)
+	if err != nil {
+		return err
+	}
+
+	return os.Chmod(filename, fi.Mode())
+}
+
+func showErrorMessage(err error, parent fyne.Window) {
+	dialog.ShowError(err, parent)
+}
+
+func main() {
+	args := os.Args
+	if len(args) != 5 {
+		fmt.Printf("Bad encrypt args: %v\n", args)
+		os.Exit(1)
+	}
+
+	fileName := args[1]
+	algorithm := args[2]
+	if algorithm != AlgorithmAes256Gcm {
+		fmt.Printf("Bad algorithm: %s\n", algorithm)
+		os.Exit(1)
+	}
+	keyBytes, err := hex.DecodeString(args[3])
+	if err != nil {
+		fmt.Printf("Bad key: %s, failed: %s\n", args[3], err.Error())
+		os.Exit(1)
+	}
+	if len(keyBytes) != 32 {
+		fmt.Printf("Bad key length: %d\n", len(keyBytes))
+		os.Exit(1)
+	}
+	nonceBytes, err := hex.DecodeString(args[4])
+	if err != nil {
+		fmt.Printf("Bad nonce: %s, failed: %s\n", args[4], err.Error())
+		os.Exit(1)
+	}
+	if len(nonceBytes) != 12 {
+		fmt.Printf("Bad nonce length: %d\n", len(nonceBytes))
+		os.Exit(1)
+	}
+
+	fileData, err := os.ReadFile(fileName)
+	if err != nil {
+		fmt.Printf("Read file: %s, failed: %s\n", fileName, err.Error())
+		os.Exit(1)
+	}
+
+	plaintext, err := decrypt(fileData, keyBytes, nonceBytes)
+	if err != nil {
+		fmt.Printf("Decrypt file: %s, failed: %s\n", fileName, err.Error())
+		os.Exit(1)
+	}
+
+	secureEditorApp := app.New()
+	window := secureEditorApp.NewWindow(Title)
+	window.Resize(fyne.NewSize(800, 600))
+	window.SetOnClosed(func() {
+		secureEditorApp.Quit()
+	})
+
+	textEntry := widget.NewMultiLineEntry()
+	textEntry.Wrapping = fyne.TextWrapWord
+
+	textEntry.SetText(string(plaintext))
+
+	exitButton := widget.NewButton(" [ Exit ] ", func() {
+		secureEditorApp.Quit()
+	})
+	saveButton := widget.NewButton(" [ Save ] ", func() {
+		plaintext := textEntry.Text
+		ciphertext, err := encrypt([]byte(plaintext), keyBytes, nonceBytes)
+		if err != nil {
+			showErrorMessage(err, window)
+			return
+		}
+		err = writeFilePreserveMode(fileName, ciphertext)
+		if err != nil {
+			showErrorMessage(err, window)
+			return
+		}
+		secureEditorApp.Quit()
+	})
+
+	content := container.NewBorder(
+		nil, // top
+		container.NewBorder(nil, nil, nil, container.NewHBox(exitButton, saveButton), nil), // bottom
+		nil,       // left
+		nil,       // right
+		textEntry, // center
+	)
+
+	window.SetContent(content)
+	window.CenterOnScreen()
+	window.ShowAndRun()
+}