init push

internal/service/secret_protector.go

@@ -0,0 +1,62 @@
+package service
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"io"
+)
+
+type AESGCMProtector struct {
+	key []byte
+}
+
+func NewAESGCMProtectorFromBase64(keyB64 string) (*AESGCMProtector, error) {
+	if keyB64 == "" {
+		return nil, errors.New("empty key")
+	}
+	key, err := base64.StdEncoding.DecodeString(keyB64)
+	if err != nil {
+		return nil, err
+	}
+	if len(key) != 32 {
+		return nil, errors.New("key must be 32 bytes (base64-encoded)")
+	}
+	return &AESGCMProtector{key: key}, nil
+}
+
+func (p *AESGCMProtector) Encrypt(plain []byte) ([]byte, error) {
+	block, err := aes.NewCipher(p.key)
+	if err != nil {
+		return nil, err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+	ciphertext := gcm.Seal(nonce, nonce, plain, nil)
+	return ciphertext, nil
+}
+
+func (p *AESGCMProtector) Decrypt(ciphertext []byte) ([]byte, error) {
+	block, err := aes.NewCipher(p.key)
+	if err != nil {
+		return nil, err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	if len(ciphertext) < gcm.NonceSize() {
+		return nil, errors.New("ciphertext too short")
+	}
+	nonce := ciphertext[:gcm.NonceSize()]
+	data := ciphertext[gcm.NonceSize():]
+	return gcm.Open(nil, nonce, data, nil)
+}