authenticate k8 operator via token

k8-operator/packages/crypto/crypto.go

@@ -0,0 +1,28 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+)
+
+func DecryptSymmetric(key []byte, encryptedPrivateKey []byte, tag []byte, IV []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	aesgcm, err := cipher.NewGCMWithNonceSize(block, len(IV))
+	if err != nil {
+		return nil, err
+	}
+
+	var nonce = IV
+	var ciphertext = append(encryptedPrivateKey, tag...)
+
+	plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	return plaintext, nil
+}