first commit

backend/decryptor.go

@@ -0,0 +1,156 @@
+package backend
+
+import (
+	"archive/zip"
+	"bytes"
+	"context"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/wailsapp/wails/v2/pkg/runtime"
+)
+
+type Decryptor struct {
+	ctx context.Context
+}
+
+func NewDecryptor() *Decryptor {
+	return &Decryptor{}
+}
+
+func (d *Decryptor) OnStartup(ctx context.Context) {
+	d.ctx = ctx
+	fmt.Printf("ctx: %v\n", ctx)
+}
+
+func (d *Decryptor) SelectPrivateKeyFile() (string, error) {
+	return runtime.OpenFileDialog(d.ctx, runtime.OpenDialogOptions{
+		Title: "Select Private Key File",
+		Filters: []runtime.FileFilter{
+			{DisplayName: "PEM Files", Pattern: "*.pem"},
+		},
+	})
+}
+
+func (d *Decryptor) SelectEncryptedFile() (string, error) {
+	return runtime.OpenFileDialog(d.ctx, runtime.OpenDialogOptions{
+		Title: "Select Encrypted Zip File",
+		Filters: []runtime.FileFilter{
+			{DisplayName: "Encrypted Zip", Pattern: "*.zip"},
+		},
+	})
+}
+
+func (d *Decryptor) SelectOutputDirectory() (string, error) {
+	return runtime.OpenDirectoryDialog(d.ctx, runtime.OpenDialogOptions{
+		Title: "Select Output Directory",
+	})
+}
+func (d *Decryptor) DecryptHybridZip(encryptedZipPath string, privKeyPath string, outputDir string) error {
+	r, err := zip.OpenReader(encryptedZipPath)
+	if err != nil {
+		return err
+	}
+	defer r.Close()
+
+	var encData, encKey []byte
+	for _, f := range r.File {
+		rc, _ := f.Open()
+		data, _ := io.ReadAll(rc)
+		rc.Close()
+		fmt.Printf("f.Name: %v\n", f.Name)
+		switch f.Name {
+		case "encrypted_data.bin":
+			encData = data
+		case "encrypted_key.bin":
+			encKey = data
+		}
+	}
+	if encData == nil || encKey == nil {
+		return errors.New("missing encrypted files")
+	}
+
+	privKey, err := loadPrivateKey(privKeyPath)
+	if err != nil {
+		return err
+	}
+	aesKey, err := rsa.DecryptPKCS1v15(rand.Reader, privKey, encKey)
+	if err != nil {
+		return err
+	}
+
+	zipData, err := decryptAES(encData, aesKey)
+	if err != nil {
+		return err
+	}
+
+	zipReader, err := zip.NewReader(bytes.NewReader(zipData), int64(len(zipData)))
+	if err != nil {
+		return err
+	}
+	var originalFolderName string
+
+	for _, f := range zipReader.File {
+		dirPath := filepath.Dir(f.Name)
+
+		if len(dirPath) > 0 && originalFolderName == "" {
+			originalFolderName = dirPath
+		}
+
+	}
+
+	if originalFolderName == "" {
+		return errors.New("failed to detect original folder name")
+	}
+
+	outputZip := filepath.Join(outputDir, originalFolderName+".zip")
+
+	err = os.WriteFile(outputZip, zipData, 0644)
+	if err != nil {
+		return fmt.Errorf("failed to write decrypted zip file: %w", err)
+	}
+
+	return nil
+}
+
+func loadPrivateKey(path string) (*rsa.PrivateKey, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	block, _ := pem.Decode(data)
+	if block == nil || block.Type != "PRIVATE KEY" {
+		return nil, errors.New("invalid private key format")
+	}
+	priv, err := x509.ParsePKCS8PrivateKey(block.Bytes)
+	if err != nil {
+		return nil, err
+	}
+	return priv.(*rsa.PrivateKey), nil
+}
+
+func decryptAES(cipherData, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	nonceSize := gcm.NonceSize()
+	if len(cipherData) < nonceSize {
+		return nil, fmt.Errorf("cipher data too short")
+	}
+	nonce, cipherText := cipherData[:nonceSize], cipherData[nonceSize:]
+	return gcm.Open(nil, nonce, cipherText, nil)
+}