Local-first runtime cleanup and recovery hardening

internal/localdb/encryption_test.go

@@ -0,0 +1,97 @@
+package localdb
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestEncryptCreatesPersistentKeyFile(t *testing.T) {
+	stateDir := t.TempDir()
+	t.Setenv("QFS_STATE_DIR", stateDir)
+	t.Setenv("QUOTEFORGE_ENCRYPTION_KEY", "")
+
+	ciphertext, err := Encrypt("secret-password")
+	if err != nil {
+		t.Fatalf("encrypt: %v", err)
+	}
+	if ciphertext == "" {
+		t.Fatal("expected ciphertext")
+	}
+
+	keyPath := filepath.Join(stateDir, encryptionKeyFileName)
+	info, err := os.Stat(keyPath)
+	if err != nil {
+		t.Fatalf("stat key file: %v", err)
+	}
+	if info.Mode().Perm() != 0600 {
+		t.Fatalf("expected 0600 key file, got %v", info.Mode().Perm())
+	}
+}
+
+func TestDecryptMigratesLegacyCiphertext(t *testing.T) {
+	stateDir := t.TempDir()
+	t.Setenv("QFS_STATE_DIR", stateDir)
+	t.Setenv("QUOTEFORGE_ENCRYPTION_KEY", "")
+
+	legacyCiphertext := encryptWithKeyForTest(t, getLegacyEncryptionKey(), "legacy-password")
+
+	plaintext, migrated, err := DecryptWithMetadata(legacyCiphertext)
+	if err != nil {
+		t.Fatalf("decrypt legacy: %v", err)
+	}
+	if plaintext != "legacy-password" {
+		t.Fatalf("unexpected plaintext: %q", plaintext)
+	}
+	if !migrated {
+		t.Fatal("expected legacy ciphertext to require migration")
+	}
+
+	currentCiphertext, err := Encrypt("legacy-password")
+	if err != nil {
+		t.Fatalf("encrypt current: %v", err)
+	}
+	plaintext, migrated, err = DecryptWithMetadata(currentCiphertext)
+	if err != nil {
+		t.Fatalf("decrypt current: %v", err)
+	}
+	if migrated {
+		t.Fatal("did not expect current ciphertext to require migration")
+	}
+}
+
+func encryptWithKeyForTest(t *testing.T, key []byte, plaintext string) string {
+	t.Helper()
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		t.Fatalf("new cipher: %v", err)
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		t.Fatalf("new gcm: %v", err)
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		t.Fatalf("read nonce: %v", err)
+	}
+
+	ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
+	return base64.StdEncoding.EncodeToString(ciphertext)
+}
+
+func TestLegacyEncryptionKeyRemainsDeterministic(t *testing.T) {
+	hostname, _ := os.Hostname()
+	expected := sha256.Sum256([]byte(hostname + "quoteforge-salt-2024"))
+	actual := getLegacyEncryptionKey()
+	if string(actual) != string(expected[:]) {
+		t.Fatal("legacy key derivation changed")
+	}
+}