feat(crypto): AES-256-GCM шифрование секретов учёток

internal/crypto/crypto_test.go

@@ -0,0 +1,64 @@
+package crypto
+
+import (
+	"bytes"
+	"testing"
+)
+
+func key32() []byte {
+	k := make([]byte, 32)
+	for i := range k {
+		k[i] = byte(i + 1)
+	}
+	return k
+}
+
+func TestEncryptDecryptRoundTrip(t *testing.T) {
+	c, err := NewCipher(key32())
+	if err != nil {
+		t.Fatal(err)
+	}
+	plain := []byte("selectel-api-secret-token")
+	enc, err := c.Encrypt(plain)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if enc == string(plain) {
+		t.Fatal("ciphertext must differ from plaintext")
+	}
+	dec, err := c.Decrypt(enc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(dec, plain) {
+		t.Fatalf("round-trip mismatch: %q != %q", dec, plain)
+	}
+}
+
+func TestEncryptNonDeterministic(t *testing.T) {
+	c, _ := NewCipher(key32())
+	a, _ := c.Encrypt([]byte("same"))
+	b, _ := c.Encrypt([]byte("same"))
+	if a == b {
+		t.Fatal("nonce must randomize ciphertext")
+	}
+}
+
+func TestDecryptTamperFails(t *testing.T) {
+	c, _ := NewCipher(key32())
+	enc, _ := c.Encrypt([]byte("data"))
+	// испортить последний символ base64
+	tampered := enc[:len(enc)-1] + "A"
+	if tampered == enc {
+		tampered = enc[:len(enc)-1] + "B"
+	}
+	if _, err := c.Decrypt(tampered); err == nil {
+		t.Fatal("GCM must reject tampered ciphertext")
+	}
+}
+
+func TestNewCipherRejectsBadKey(t *testing.T) {
+	if _, err := NewCipher([]byte("short")); err == nil {
+		t.Fatal("expected error for non-32-byte key")
+	}
+}