Base webui and backend additions

service/internal/settings/crypto.go

@@ -0,0 +1,59 @@
+package settings
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"io"
+)
+
+func seal(plaintext []byte, key []byte) (nonce []byte, ciphertext []byte, err error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, nil, fmt.Errorf("aes cipher: %w", err)
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, nil, fmt.Errorf("gcm: %w", err)
+	}
+
+	nonce = make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, nil, fmt.Errorf("nonce: %w", err)
+	}
+
+	ciphertext = gcm.Seal(nil, nonce, plaintext, nil)
+	return nonce, ciphertext, nil
+}
+
+func open(nonce []byte, ciphertext []byte, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, fmt.Errorf("aes cipher: %w", err)
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, fmt.Errorf("gcm: %w", err)
+	}
+
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, fmt.Errorf("decrypt: %w", err)
+	}
+	return plaintext, nil
+}
+
+func decodeKey(base64Key string) ([]byte, error) {
+	key, err := base64.StdEncoding.DecodeString(base64Key)
+	if err != nil {
+		return nil, fmt.Errorf("decode key: %w", err)
+	}
+	if length := len(key); length != 16 && length != 24 && length != 32 {
+		return nil, fmt.Errorf("key must be 16, 24, or 32 bytes after base64 decode, got %d", length)
+	}
+	return key, nil
+}