Flag ciphered SCP80 fields: on-wire CNTR/PCNTR/RC are ciphertext

User-reported: the decoded CNTR (0x1830A44E41 ≈ 104 billion) cannot
be the real counter — the OTA platform shows ~200 for that card.

Root cause: per TS 102 225 Table 2 note 1, when SPI indicates
ciphering the whole block from CNTR through the secured data
(CNTR, PCNTR, RC/CC/DS, secured data) is ENCRYPTED. Only CPI, CPL,
CHI/CHL, SPI, KIc, KID and TAR travel in the clear. Our decoder
parsed the ciphertext bytes as if they were the real CNTR/PCNTR/RC
and presented them as such — misleading (the true values are only
recoverable after 3DES decryption with the card's keys).

Fix:
- _decode_secured_packet: emit 'ciphered': True when SPI1.b3 is set
  (wire hex values kept for reference); docstring documents the
  ciphered block.
- _decode_response_packet: accepts ciphered (command SPI2.b5, PoR
  ciphering) and flags the response likewise; database context now
  carries por_ciphered from the ENVELOPE so the GET RESPONSE PoR
  inherits it. Standalone SMS-SUBMIT PoRs carry no SPI — state
  unknowable, defaults to False (documented).
- Frontend: CNTR/PCNTR/RC-CC-DS labels get "(encrypted)" when the
  respective packet is ciphered (command, response, and ENVELOPE
  response renderings).

Tests: +4 TestSecuredCiphering (ciphered flagged, unciphered plain
CNTR e.g. 200, response flag, PoR-via-context). 348 total. Version
1.18.0, SW cache simtrace-analyser-v26.

frontend/index.html

@@ -633,13 +633,14 @@ function responseRows(resp) {
         }
     }
     if (resp.rpl !== undefined) {
+        const renc = resp.ciphered ? ' (encrypted)' : '';
         rows.push(['Response packet', 'Response Packet Length ' + resp.rpl + ' · Response Header Length ' + resp.rhl]);
         rows.push(['TAR', '0x' + resp.tar]);
-        rows.push(['CNTR', '0x' + resp.cntr]);
-        rows.push(['PCNTR', resp.pcntr]);
+        rows.push(['CNTR' + renc, '0x' + resp.cntr]);
+        rows.push(['PCNTR' + renc, resp.pcntr]);
         const st = resp.status || {};
         rows.push(['Status', '0x' + st.code + (st.name ? ' — ' + st.name : '')]);
-        if (resp.rc_cc_ds) rows.push(['RC/CC/DS', resp.rc_cc_ds]);
+        if (resp.rc_cc_ds) rows.push(['RC/CC/DS' + renc, resp.rc_cc_ds]);
         if (resp.data) rows.push(['Response data', resp.data]);
     }
 
@@ -763,23 +764,27 @@ function cmdRows(cmd) {
             rows.push(['KIc', 'key ' + sec.kic.key + ' — ' + sec.kic.algo]);
             rows.push(['KID', 'key ' + sec.kid.key + ' — ' + sec.kid.algo]);
             rows.push(['TAR', '0x' + sec.tar]);
-            rows.push(['CNTR', '0x' + sec.cntr]);
-            rows.push(['PCNTR', sec.pcntr]);
-            if (sec.rc_cc_ds) rows.push(['RC/CC/DS', sec.rc_cc_ds]);
+            // When the packet is ciphered, CNTR/PCNTR/RC-CC-DS on the wire
+            // are ciphertext (TS 102 225 Table 2 note 1) — not real values.
+            const enc = sec.ciphered ? ' (encrypted)' : '';
+            rows.push(['CNTR' + enc, '0x' + sec.cntr]);
+            rows.push(['PCNTR' + enc, sec.pcntr]);
+            if (sec.rc_cc_ds) rows.push(['RC/CC/DS' + enc, sec.rc_cc_ds]);
             rows.push(['Secured data', sec.data]);
         }
 
         const rp = t.response_packet;
-        if (rp && !rp.raw) {
-            rows.push(['Response packet', 'Response Packet Length ' + rp.rpl + ' · Response Header Length ' + rp.rhl]);
-            rows.push(['TAR', '0x' + rp.tar]);
-            rows.push(['CNTR', '0x' + rp.cntr]);
-            rows.push(['PCNTR', rp.pcntr]);
-            const st = rp.status || {};
-            rows.push(['Status', '0x' + st.code + (st.name ? ' — ' + st.name : '')]);
-            if (rp.rc_cc_ds) rows.push(['RC/CC/DS', rp.rc_cc_ds]);
-            rows.push(['Response data', rp.data]);
-        }
+    if (rp && !rp.raw) {
+        const renc = rp.ciphered ? ' (encrypted)' : '';
+        rows.push(['Response packet', 'Response Packet Length ' + rp.rpl + ' · Response Header Length ' + rp.rhl]);
+        rows.push(['TAR', '0x' + rp.tar]);
+        rows.push(['CNTR' + renc, '0x' + rp.cntr]);
+        rows.push(['PCNTR' + renc, rp.pcntr]);
+        const st = rp.status || {};
+        rows.push(['Status', '0x' + st.code + (st.name ? ' — ' + st.name : '')]);
+        if (rp.rc_cc_ds) rows.push(['RC/CC/DS' + renc, rp.rc_cc_ds]);
+        rows.push(['Response data', rp.data]);
+    }
     }
 
     if (!rows.length) return '';
@@ -1901,7 +1906,7 @@ function onFilterChange() {
 }
 
 // ──────────────────── Versioning ────────────────────
-const PWA_VERSION = '1.17.1';
+const PWA_VERSION = '1.18.0';
 const MIN_SERVER_VERSION = '1.0.0';
 
 function parseVersion(v) {

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simtrace-analyser-v25';
+const CACHE = 'simtrace-analyser-v26';
 
 const PRECACHE = [
     'index.html',

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.backends._legacy:_Backend"
 
 [project]
 name = "simtrace2-pysniff"
-version = "1.17.1"
+version = "1.18.0"
 description = "Python-based sniffing tool for SIMtrace2 hardware (SIM card communication sniffer)"
 readme = {file = "README.md", content-type = "text/markdown"}
 license = {text = "GPL-2.0-or-later"}

simtrace2_pysniff/__init__.py

@@ -6,7 +6,7 @@ from .gsmtap import GsmtapSender, GsmtapReceiver
 from .pcap import PcapWriter
 from .dump import FileDumper, format_message
 
-__version__ = '1.17.1'
+__version__ = '1.18.0'
 __all__ = [
     'SniffSession',
     'DeviceDisconnected',

simtrace2_pysniff/server/database.py

@@ -310,11 +310,13 @@ class Database:
             file_ok = True
         elif ins in (0xB0, 0xD6):
             file_ok = (d.get('p1p2') or {}).get('value', 0) == 0
+        sec = ((d.get('cmd') or {}).get('tpdu') or {}).get('secured') or {}
         return {
             'ins': ins,
             'ins_name': d.get('ins_name'),
             'sw1': (d.get('sw') or {}).get('sw1'),
             'file_ok': file_ok,
+            'por_ciphered': bool((sec.get('spi') or {}).get('por_ciphered')),
         }
 
     def _selection_after(self, d, sel):

simtrace2_pysniff/server/decode.py

@@ -2293,6 +2293,11 @@ def _decode_secured_packet(body):
 
     *body* is the TP-UD remainder after the UDH (CPI IEI 0x70).  Returns a
     dict of the decoded header fields; ``{'raw': hex}`` when unparseable.
+
+    When SPI indicates ciphering, the on-wire CNTR, PCNTR and RC/CC/DS are
+    CIPHERTEXT (TS 102 225 Table 2, note 1 — the whole block from CNTR
+    through the secured data is encrypted); ``'ciphered'`` is set so
+    callers do not present those bytes as the real values.
     """
     if not body or len(body) < 16:
         return {'raw': body.hex().upper()} if body else {}
@@ -2305,6 +2310,7 @@ def _decode_secured_packet(body):
     cntr = body[10:15]
     pcntr = body[15]
     spi1, spi2 = spi[0], spi[1]
+    ciphered = bool(spi1 & 0x04)
     rc_cc_ds_kind = spi1 & 0x03
     rc_cc_ds_len = max(0, chl - 13)  # 13 = SPI+KIc+KID+TAR+CNTR+PCNTR
     rc_cc_ds = body[16:16 + rc_cc_ds_len]
@@ -2313,6 +2319,7 @@ def _decode_secured_packet(body):
     result = {
         'cpl': cpl,
         'chl': chl,
+        'ciphered': ciphered,
         'spi': {
             'hex': spi.hex().upper(),
             'counter': _OTA_COUNTER.get((spi1 >> 4) & 0x03, 'reserved'),
@@ -2349,11 +2356,17 @@ def _decode_secured_packet(body):
     return result
 
 
-def _decode_response_packet(body):
+def _decode_response_packet(body, ciphered=False):
     """Decode a Response Packet (TS 102 225 §5.2 / TS 31.115 §4.4).
 
     *body* is the TP-UD remainder after the UDH (RPI IEI 0x71).  Returns a
     dict of the decoded header fields; ``{'raw': hex}`` when unparseable.
+
+    *ciphered* reflects the command's SPI2.b5 (PoR ciphering): when set,
+    the on-wire CNTR, PCNTR and RC/CC/DS are ciphertext (Table 4, note 1)
+    and ``'ciphered'`` is set in the result.  A standalone Response Packet
+    (e.g. inside an SMS-SUBMIT) carries no SPI, so the state is unknowable
+    there and defaults to False.
     """
     if not body or len(body) < 13:
         return {'raw': body.hex().upper()} if body else {}
@@ -2370,6 +2383,7 @@ def _decode_response_packet(body):
     result = {
         'rpl': rpl,
         'rhl': rhl,
+        'ciphered': bool(ciphered),
         'tar': tar.hex().upper(),
         'cntr': cntr.hex().upper(),
         'pcntr': pcntr,
@@ -3929,7 +3943,8 @@ def decode_message(raw_data, prev=None):
                     # RPI mapping precedes the packet: UDHL='02', IEIa='71',
                     # IEIDLa='00' (TS 31.115 §4.4).
                     if data[:3] == b'\x02\x71\x00':
-                        result['response'] = _decode_response_packet(data[3:])
+                        result['response'] = _decode_response_packet(
+                            data[3:], ciphered=bool(prev.get('por_ciphered')))
                 else:
                     response = _decode_response_for(prev_ins, remaining[:cmd_body_len])
                     if response:

tests/test_decode.py

@@ -2080,6 +2080,54 @@ class TestSwUiccSpecific(unittest.TestCase):
         self.assertIsNone(self._sw('6205')['name'])
 
 
+class TestSecuredCiphering(unittest.TestCase):
+    """Ciphered SCP80 packets: on-wire CNTR/PCNTR/RC are ciphertext
+    (TS 102 225 Table 2 note 1) — flagged, not shown as real values."""
+
+    def test_ciphered_packet_flagged(self):
+        # stk_test1-style SMS-PP DOWNLOAD secured packet (ciphering on):
+        # CNTR on the wire is ciphertext; the card's real counter (~200)
+        # is only recoverable after 3DES decryption.
+        from simtrace2_pysniff.server.decode import _decode_secured_packet
+        sec = bytes.fromhex('003815160115 15b000011830a44e4191ad45d0ec'
+                            '2a291315986468a539d248fcdce7952c31cd635baec'
+                            '7e93a5d567b59f6283316c0dad8603bf3'.replace(' ', ''))
+        r = _decode_secured_packet(sec)
+        self.assertTrue(r['ciphered'])
+        self.assertTrue(r['spi']['ciphering'])
+        self.assertEqual(r['cntr'], '1830A44E41')  # wire bytes kept, flagged
+
+    def test_unciphered_packet_plain_cntr(self):
+        # SPI1 = 0x10: counter present, NO ciphering, RC/CC/DS none →
+        # CNTR is genuine plaintext (e.g. 200 = 0x00000000C8).
+        from simtrace2_pysniff.server.decode import _decode_secured_packet
+        sec = bytes.fromhex('00100d10011515b0000100000000c800aabb')
+        r = _decode_secured_packet(sec)
+        self.assertFalse(r['ciphered'])
+        self.assertEqual(r['cntr'], '00000000C8')
+        self.assertNotIn('rc_cc_ds', r)
+
+    def test_response_packet_ciphered_flag(self):
+        from simtrace2_pysniff.server.decode import _decode_response_packet
+        body = bytes.fromhex('001f0a00000000000000500000ab12800101230d08a0000001510000000f9a9000')
+        r = _decode_response_packet(body, ciphered=True)
+        self.assertTrue(r['ciphered'])
+        r2 = _decode_response_packet(body)
+        self.assertFalse(r2['ciphered'])
+
+    def test_por_ciphered_via_context(self):
+        # GET RESPONSE after a ciphered ENVELOPE: the response packet's
+        # ciphered flag flows from the command's SPI2.b5 via prev context.
+        prev = {'ins': 0xC2, 'ins_name': 'ENVELOPE', 'sw1': '61',
+                'por_ciphered': True}
+        raw = bytes.fromhex('80c0000019' +
+                            '0271' +
+                            '001f0a00000000000000500000ab12800101230d08a0000001510000000f9a9000'[:0x19 * 2] +
+                            '9000')
+        r = decode_message(raw, prev=prev)
+        self.assertTrue(r['response']['ciphered'])
+
+
 class TestSpiBits(unittest.TestCase):
     """TS 102 225 §5.1.1: SPI1 b3 = ciphering, SPI2 b5 = PoR ciphering."""
 

tests/test_pcap_import.py

@@ -197,7 +197,7 @@ class TestImportEndpoint(unittest.TestCase):
 class TestVersion(unittest.TestCase):
     def test_package_version(self):
         from simtrace2_pysniff import __version__
-        self.assertEqual(__version__, '1.17.1')
+        self.assertEqual(__version__, '1.18.0')
 
     def test_status_includes_version(self):
         import os