fix(security): treat a new identity key as a message request, never as a known contact

A stranger could pick the display name of an existing contact ("Mom") and appear as that contact. Messages from a key that is not in the contact list now open a message request labelled "(unknown)": no replies, read receipts, typing indicators, calls or name in notifications until the user accepts it and names the contact themselves. Names that look like an existing contact (case, diacritics, Cyrillic/Greek homoglyphs, invisible characters) also show a warning in the real contact's chat. When the relay account of a known contact shows up with a different key, the chat shows "safety number changed", verification is cleared and the session that now belongs to the other key is dropped before sending, so a reply never goes to the new key.
2026-10-23 10:50:42 +02:00
parent 2f6b542f24
commit 717aeed4ff
23 changed files with 999 additions and 67 deletions
@@ -0,0 +1,78 @@
+/// Bezpečnostní upozornění uprostřed konverzace. Vypadá jinak než bublina
+/// (nikdo ho neposlal), aby nešlo zaměnit se zprávou protistrany.
+library;
+
+import 'package:flutter/material.dart';
+import 'package:sepot/core/l10n/l10n.dart';
+import 'package:sepot/core/theme/app_theme.dart';
+import 'package:sepot/models/message.dart';
+
+class SafetyNoticeRow extends StatelessWidget {
+  const SafetyNoticeRow({
+    super.key,
+    required this.notice,
+    required this.contactName,
+    this.claimedName,
+    this.onVerify,
+  });
+
+  final MessageNotice notice;
+  final String contactName;
+
+  /// Jméno, které si zvolil neznámý odesílatel ([MessageNotice.lookalikeRequest]).
+  final String? claimedName;
+
+  /// Odkaz na porovnání bezpečnostního kódu (null = bez tlačítka).
+  final VoidCallback? onVerify;
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = context.l10n;
+    final text = switch (notice) {
+      MessageNotice.identityChanged => l10n.noticeIdentityChanged(contactName),
+      MessageNotice.lookalikeRequest =>
+        l10n.noticeLookalikeRequest(claimedName ?? '', contactName),
+    };
+    return Padding(
+      padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 10),
+      child: Container(
+        padding: const EdgeInsets.fromLTRB(14, 12, 14, 6),
+        decoration: BoxDecoration(
+          color: SepotColors.surfaceVariant,
+          borderRadius: BorderRadius.circular(14),
+          border: Border.all(color: SepotColors.warning),
+        ),
+        child: Column(
+          children: [
+            Row(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                const Icon(Icons.gpp_maybe_rounded,
+                    size: 18, color: SepotColors.warning),
+                const SizedBox(width: 8),
+                Expanded(
+                  child: Text(
+                    text,
+                    style: const TextStyle(
+                        fontSize: 13, color: SepotColors.textPrimary),
+                  ),
+                ),
+              ],
+            ),
+            if (onVerify != null &&
+                notice == MessageNotice.identityChanged)
+              Align(
+                alignment: Alignment.centerRight,
+                child: TextButton(
+                  onPressed: onVerify,
+                  child: Text(l10n.noticeVerifyAction),
+                ),
+              )
+            else
+              const SizedBox(height: 6),
+          ],
+        ),
+      ),
+    );
+  }
+}