131 lines
2.6 KiB
Go
131 lines
2.6 KiB
Go
// backend\crypto.go
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package main
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"encoding/base64"
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"errors"
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"io"
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"os"
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"path/filepath"
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"strings"
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)
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// Wir speichern den Key neben der EXE, damit encryption nach Neustart weiterhin entschlüsselbar ist.
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// Datei enthält base64(32 bytes).
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const settingsKeyFile = "recorder_settings.key"
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func settingsKeyPath() string {
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if p, err := resolvePathRelativeToApp(settingsKeyFile); err == nil && strings.TrimSpace(p) != "" {
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return p
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}
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return settingsKeyFile
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}
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func loadOrCreateSettingsKey() ([]byte, error) {
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p := settingsKeyPath()
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// Load existing
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if b, err := os.ReadFile(p); err == nil {
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s := strings.TrimSpace(string(b))
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if s == "" {
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return nil, errors.New("settings key file ist leer")
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}
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key, err := base64.StdEncoding.DecodeString(s)
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if err != nil {
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return nil, err
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}
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if len(key) != 32 {
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return nil, errors.New("settings key muss 32 bytes sein")
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}
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return key, nil
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}
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// Create new
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key := make([]byte, 32)
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if _, err := io.ReadFull(rand.Reader, key); err != nil {
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return nil, err
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}
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enc := base64.StdEncoding.EncodeToString(key)
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// Ordner sicherstellen
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if dir := filepath.Dir(p); dir != "." && strings.TrimSpace(dir) != "" {
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_ = os.MkdirAll(dir, 0o755)
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}
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// best effort: Datei schreiben (für Windows perms gibt's hier keinen sauberen cross-platform chmod)
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if err := atomicWriteFile(p, []byte(enc+"\n")); err != nil {
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return nil, err
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}
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return key, nil
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}
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func encryptSettingString(plain string) (string, error) {
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key, err := loadOrCreateSettingsKey()
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if err != nil {
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return "", err
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}
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block, err := aes.NewCipher(key)
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if err != nil {
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return "", err
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}
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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return "", err
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}
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nonce := make([]byte, gcm.NonceSize())
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if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
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return "", err
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}
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ct := gcm.Seal(nil, nonce, []byte(plain), nil)
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out := append(nonce, ct...)
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return base64.StdEncoding.EncodeToString(out), nil
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}
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func decryptSettingString(enc string) (string, error) {
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enc = strings.TrimSpace(enc)
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if enc == "" {
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return "", nil
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}
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key, err := loadOrCreateSettingsKey()
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if err != nil {
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return "", err
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}
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raw, err := base64.StdEncoding.DecodeString(enc)
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if err != nil {
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return "", err
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}
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block, err := aes.NewCipher(key)
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if err != nil {
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return "", err
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}
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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return "", err
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}
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ns := gcm.NonceSize()
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if len(raw) < ns+1 {
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return "", errors.New("ciphertext zu kurz")
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}
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nonce := raw[:ns]
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ct := raw[ns:]
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pt, err := gcm.Open(nil, nonce, ct, nil)
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if err != nil {
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return "", err
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}
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return string(pt), nil
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}
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