Merge pull request #448 from DidierA/parity-check

hf 14a sniff: add parity checks

software/script/chameleon_cli_unit.py

@@ -31,6 +31,7 @@ from chameleon_utils import (
     execute_tool,
     tqdm_if_exists,
     print_key_table,
+    odd_parity_byte,
     default_cwd
 )
 
@@ -7797,7 +7798,7 @@ class HF14ASniff(BaseCLIUnit):
         # Bit 15 of szBits: 0 = reader→card, 1 = card→reader (new firmware).
         # Old firmware always sends bit15=0; parser is backward compatible.
         buf = bytes(resp.data)
-        frames = []  # (szBits, data, is_tx)
+        frames = []  # (szBits, data, is_tx, parity)
         i = 0
         while i + 2 <= len(buf):
             hdr = (buf[i] << 8) | buf[i+1]
@@ -7812,6 +7813,9 @@ class HF14ASniff(BaseCLIUnit):
             raw = buf[i:i+szBytes]
             i += szBytes
 
+            # parity array: parity for each byte of data array
+            parity_bits = []
+
             # ISO14443-A frames include one parity bit per byte.
             # Short frames (< 8 bits, e.g. REQA=7 bits) have no parity.
             # All other frames: szBits = data_bytes * 9, strip every 9th bit.
@@ -7827,19 +7831,20 @@ class HF14ASniff(BaseCLIUnit):
                     for b in range(8):
                         val |= all_bits[nb * 9 + b] << b
                     stripped.append(val)
+                    parity_bits.append(all_bits[nb * 9 + 8])
                 data = bytes(stripped)
                 szBits = n_bytes * 8
             else:
                 data = raw
 
-            frames.append((szBits, data, is_tx))
+            frames.append((szBits, data, is_tx, parity_bits))
 
         if not frames:
             print(f"{CR}No frames decoded{C0}")
             return
 
-        rx_count = sum(1 for _, _, tx in frames if not tx)
-        tx_count = sum(1 for _, _, tx in frames if tx)
+        rx_count = sum(1 for _, _, tx, _ in frames if not tx)
+        tx_count = sum(1 for _, _, tx, _ in frames if tx)
         if tx_count > 0:
             print(f" Captured : {CG}{len(frames)}{C0} frame(s)  "
                   f"({CY}{rx_count}{C0} reader→card  {CG}{tx_count}{C0} card→reader)")
@@ -7855,8 +7860,11 @@ class HF14ASniff(BaseCLIUnit):
         last_auth_keytype = None
         last_auth_block = None
 
-        for n, (szBits, data, is_tx) in enumerate(frames):
-            hex_str = ' '.join(f'{b:02x}' for b in data)
+        for n, (szBits, data, is_tx, parity_bits) in enumerate(frames):
+            if (len(data) == len(parity_bits)):
+                hex_str = ' '.join(f"{b:02x}{'!' if odd_parity_byte(b)!= p else ' '}" for (b,p) in zip(data,parity_bits))
+            else:
+                hex_str = ' '.join(f"{b:02x}" for b in data)
 
             # is_tx==True means CU transmitted (card -> reader).
             # is_tx==False means reader -> card.
@@ -7898,7 +7906,7 @@ class HF14ASniff(BaseCLIUnit):
 
         # Summary block (pass only reader→card frames for protocol decode)
         print()
-        _print_14a_sniff_summary(frames)  # full frames needed for nonce extraction
+        _print_14a_sniff_summary([(szBits, data, is_tx) for (szBits, data, is_tx,parity) in frames])  # full frames needed for nonce extraction
 
 
 @hf_14a.command("auth-trace")

software/script/chameleon_utils.py

@@ -209,6 +209,11 @@ def parity_to_str(nt_par_err):
         ]
     )
 
+def odd_parity_byte(value: int) -> int:
+    assert(value >=0 and value <= 255)
+    for i in [4, 2, 1]:
+        value ^= value >> i
+    return (value & 1) ^ 1
 
 def execute_tool(tool_name, args):
     if sys.platform == "win32":