hf mf elog --decrypt skip records with found keys

CHANGELOG.md

@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+ - `hf mf elog --decrypt` skip records with found keys (@taichunmin)
  - Added command to check keys of multiple sectors at once (@taichunmin)
  - Fixed unused target key type parameter for nested (@petepriority)
  - Skip already used items `hf mf elog --decrypt` (@p-l-)

software/script/chameleon_cli_unit.py

@@ -25,6 +25,7 @@
 from chameleon_enum import Command, Status, SlotNumber, TagSenseType, TagSpecificType
 from chameleon_enum import MifareClassicWriteMode, MifareClassicPrngType, MifareClassicDarksideStatus, MfcKeyType
 from chameleon_enum import AnimationMode, ButtonPressFunction, ButtonType, MfcValueBlockOperator
+from crypto1 import Crypto1
 
 # NXP IDs based on https://www.nxp.com/docs/en/application-note/AN10833.pdf
 type_id_SAK_dict = {0x00: "MIFARE Ultralight Classic/C/EV1/Nano | NTAG 2xx",
@@ -1240,32 +1241,34 @@ def _run_mfkey32v2(items):
 
 
 class ItemGenerator:
-    def __init__(self, rs, i=0, j=1):
-        self.rs = rs
+    def __init__(self, rs, uid_found_keys = set()):
+        self.rs: list = rs
+        self.progress = 0
         self.i = 0
         self.j = 1
         self.found = set()
         self.keys = set()
+        for known_key in uid_found_keys:
+            self.test_key(known_key)
 
     def __iter__(self):
         return self
 
     def __next__(self):
-        try:
-            item_i = self.rs[self.i]
-        except IndexError:
-            raise StopIteration
-        if self.key_from_item(item_i) in self.found:
+        size = len(self.rs)
+        if self.j >= size:
             self.i += 1
+            if self.i >= size - 1:
+                raise StopIteration
             self.j = self.i + 1
-            return next(self)
-        try:
-            item_j = self.rs[self.j]
-        except IndexError:
+        item_i, item_j = self.rs[self.i], self.rs[self.j]
+        self.progress += 1
+        self.j += 1
+        if self.key_from_item(item_i) in self.found:
+            self.progress += max(0, size - self.j)
             self.i += 1
             self.j = self.i + 1
             return next(self)
-        self.j += 1
         if self.key_from_item(item_j) in self.found:
             return next(self)
         return item_i, item_j
@@ -1274,17 +1277,20 @@ def __next__(self):
     def key_from_item(item):
         return "{uid}-{nt}-{nr}-{ar}".format(**item)
 
-    def key_found(self, key, items):
-        self.keys.add(key)
-        for item in items:
-            try:
-                if item == self.rs[self.i]:
-                    self.i += 1
-                    self.j = self.i + 1
-            except IndexError:
-                break
-        self.found.update(self.key_from_item(item) for item in items)
-
+    def test_key(self, key, items = list()):
+        for item in self.rs:
+            item_key = self.key_from_item(item)
+            if item_key in self.found:
+                continue
+            if (item in items) or (Crypto1.mfkey32_is_reader_has_key(
+                int(item['uid'], 16),
+                int(item['nt'], 16),
+                int(item['nr'], 16),
+                int(item['ar'], 16),
+                key,
+            )):
+                self.keys.add(key)
+                self.found.add(item_key)
 
 @hf_mf.command('elog')
 class HFMFELog(DeviceRequiredUnit):
@@ -1296,7 +1302,7 @@ def args_parser(self) -> ArgumentParserNoExit:
         parser.add_argument('--decrypt', action='store_true', help="Decrypt key from MF1 log list")
         return parser
 
-    def decrypt_by_list(self, rs: list):
+    def decrypt_by_list(self, rs: list, uid_found_keys: set = set()):
         """
             Decrypt key from reconnaissance log list
 
@@ -1306,16 +1312,14 @@ def decrypt_by_list(self, rs: list):
         msg1 = f"  > {len(rs)} records => "
         msg2 = f"/{(len(rs)*(len(rs)-1))//2} combinations. "
         msg3 = " key(s) found"
-        n = 1
-        gen = ItemGenerator(rs)
+        gen = ItemGenerator(rs, uid_found_keys)
+        print(f"{msg1}{gen.progress}{msg2}{len(gen.keys)}{msg3}\r", end="")
         with Pool(cpu_count()) as pool:
             for result in pool.imap(_run_mfkey32v2, gen):
-                # TODO: if some keys already recovered, test them on item before running mfkey32 on item
                 if result is not None:
-                    gen.key_found(*result)
-                print(f"{msg1}{n}{msg2}{len(gen.keys)}{msg3}\r", end="")
-                n += 1
-        print()
+                    gen.test_key(*result)
+                print(f"{msg1}{gen.progress}{msg2}{len(gen.keys)}{msg3}\r", end="")
+        print(f"{msg1}{gen.progress}{msg2}{len(gen.keys)}{msg3}")
         return gen.keys
 
     def on_exec(self, args: argparse.Namespace):
@@ -1356,22 +1360,16 @@ def on_exec(self, args: argparse.Namespace):
         for uid in result_maps.keys():
             print(f" - Detection log for uid [{uid.upper()}]")
             result_maps_for_uid = result_maps[uid]
+            uid_found_keys = set()
             for block in result_maps_for_uid:
-                print(f"  > Block {block} detect log decrypting...")
-                if 'A' in result_maps_for_uid[block]:
-                    # print(f" - A record: { result_maps[block]['A'] }")
-                    records = result_maps_for_uid[block]['A']
-                    if len(records) > 1:
-                        result_maps[uid][block]['A'] = self.decrypt_by_list(records)
-                    else:
-                        print(f"  > {len(records)} record")
-                if 'B' in result_maps_for_uid[block]:
-                    # print(f" - B record: { result_maps[block]['B'] }")
-                    records = result_maps_for_uid[block]['B']
-                    if len(records) > 1:
-                        result_maps[uid][block]['B'] = self.decrypt_by_list(records)
-                    else:
-                        print(f"  > {len(records)} record")
+                for keyType in 'AB':
+                    records = result_maps_for_uid[block][keyType] if keyType in result_maps_for_uid[block] else []
+                    if len(records) < 1:
+                        continue
+                    print(f"  > Decrypting block {block} key {keyType} detect log...")
+                    result_maps[uid][block][keyType] = self.decrypt_by_list(records, uid_found_keys)
+                    uid_found_keys.update(result_maps[uid][block][keyType])
+
             print("  > Result ---------------------------")
             for block in result_maps_for_uid.keys():
                 if 'A' in result_maps_for_uid[block]:

software/script/crypto1.py

@@ -0,0 +1,107 @@
+LFSR48_FILTER_A = 0x9E98
+LFSR48_FILTER_B = 0xB48E
+LFSR48_FILTER_C = 0xEC57E80A
+LFSR48_POLY = 0xE882B0AD621
+U8_TO_ODD4 = [((i & 0x80) >> 4) + ((i & 0x20) >> 3) + ((i & 0x08) >> 2) + ((i & 0x02) >> 1) for i in range(256)]
+EVEN_PARITY_U8 = [0 for i in range(256)]
+
+def u8_to_odd4(u8):
+    return U8_TO_ODD4[u8 & 0xFF]
+
+def get_bit(num, x = 0):
+    return (num >> x) & 1
+
+for i in range(256):
+    tmp = i
+    tmp ^= tmp >> 4
+    tmp ^= tmp >> 2
+    EVEN_PARITY_U8[i] = (tmp ^ (tmp >> 1)) & 1
+
+def even_parity_u8(u8):
+    return EVEN_PARITY_U8[u8 & 0xFF]
+
+def odd_parity_u8(u8):
+    return even_parity_u8(u8) ^ 1
+
+def even_parity_u16(u16):
+    return even_parity_u8((u16 >> 8) ^ u16)
+
+def even_parity_u48(u48):
+    return even_parity_u16((u48 >> 32) ^ (u48 >> 16) ^ u48)
+
+def swap_endian_u16(u16):
+    return ((u16 & 0xFF) << 8) | ((u16 >> 8) & 0xFF)
+
+def swap_endian_u32(u32):
+    return swap_endian_u16(u32 & 0xFFFF) << 16 | swap_endian_u16((u32 >> 16) & 0xFFFF)
+
+"""
+ref: https://web.archive.org/web/20081010065744/http://sar.informatik.hu-berlin.de/research/publications/SAR-PR-2008-21/SAR-PR-2008-21_.pdf
+"""
+class Crypto1:
+    def __init__(self, new_lfsr48: int = 0):
+        self.lfsr48 = new_lfsr48
+
+    @property
+    def key(self) -> bytearray:
+        tmp, key = self.lfsr48, bytearray(6)
+        for i in range(6):
+            key[i] = tmp & 0xFF
+            tmp >>= 8
+        return key
+
+    @key.setter
+    def key(self, key: bytearray):
+        if (len(key) < 6):
+            raise ValueError("Key must be 6 bytes")
+        self.lfsr48 = 0
+        for i in range(6):
+            self.lfsr48 = (self.lfsr48 << 8) | key[5 - i]
+
+    def lfsr48_filter(self):
+        f = 0
+        f |= get_bit(LFSR48_FILTER_B, u8_to_odd4(self.lfsr48 >> 8)) # fb4
+        f |= get_bit(LFSR48_FILTER_A, u8_to_odd4(self.lfsr48 >> 16)) << 1 # fa4
+        f |= get_bit(LFSR48_FILTER_A, u8_to_odd4(self.lfsr48 >> 24)) << 2 # fa4
+        f |= get_bit(LFSR48_FILTER_B, u8_to_odd4(self.lfsr48 >> 32)) << 3 # fb4
+        f |= get_bit(LFSR48_FILTER_A, u8_to_odd4(self.lfsr48 >> 40)) << 4 # fa4
+        return get_bit(LFSR48_FILTER_C, f)
+
+    def lfsr48_bit(self, bit_in: int = 0, is_encrypted: bool = False) -> int:
+        out_bit = self.lfsr48_filter()
+        bit_feedback = even_parity_u48(LFSR48_POLY & self.lfsr48) ^ (bit_in & 1) ^ (is_encrypted & out_bit)
+        self.lfsr48 = (bit_feedback << 47) | (self.lfsr48 >> 1)
+        return out_bit
+
+    def lfsr48_u8(self, u8_in: int = 0, is_encrypted: bool = False) -> int:
+        out_u8 = 0
+        for i in range(8):
+            tmp = self.lfsr48_bit(u8_in >> i, is_encrypted) << i
+            out_u8 |= tmp
+        return out_u8
+
+    def lfsr48_u32(self, u32_in: int = 0, is_encrypted: bool = False) -> int:
+        u32_out = 0
+        for i in range(3, -1, -1):
+            bit_offset = i << 3
+            u32_out |= self.lfsr48_u8(u32_in >> bit_offset, is_encrypted) << bit_offset
+        return u32_out
+
+    @staticmethod
+    def prng_next(lfsr32: int, n: int = 1) -> int:
+        lfsr32 = swap_endian_u32(lfsr32)
+        for i in range(n):
+            lfsr32 = even_parity_u8(0x2D & (lfsr32 >> 16)) << 31 | (lfsr32 >> 1)
+        return swap_endian_u32(lfsr32)
+
+    @staticmethod
+    def mfkey32_is_reader_has_key(uid: int, nt: int, nrEnc: int, arEnc: int, key: str) -> bool:
+        state = Crypto1()
+        state.key = bytearray.fromhex(key)
+        state.lfsr48_u32(uid ^ nt, False) # ks0
+        state.lfsr48_u32(nrEnc, True) # ks1
+        ks2 = state.lfsr48_u32(0, False) # ks2
+        ar = arEnc ^ ks2
+        result = ar == Crypto1.prng_next(nt, 64)
+        # print(f'uid: {hex(uid)}, nt: {hex(nt)}, nrEnc: {hex(nrEnc)}, arEnc: {hex(arEnc)}, key: {key}, result = {result}')
+        return result