Merge pull request #2 from spextrow/develop

Added decoded access bits as separate column

README.md

@@ -3,7 +3,7 @@ Mifare dumps parser
 
 Mifare Classic 1k and 4k dumps parser in human readable format.  
 Dumps can be grabbed by mfoc or nfc-mfclassic tools from libnfc.org  
-Dump file size must be 4096 bytes.  
+Dump file size must be 1024 or 4096 bytes.
 
 Also try this https://github.com/asdil12/mifare-view-dump
 

mfdread.py

@@ -11,7 +11,7 @@
 import sys
 from struct import unpack 
 from datetime import datetime
-
+from bitstring import BitArray
 
 
 if len(sys.argv) == 1:
@@ -33,9 +33,61 @@ class bashcolors:
     ENDC = '\033[0m'
 
 
+def accbits_for_blocknum(accbits_str, blocknum):
+    '''
+    Decodes the access bit string for block "blocknum".
+    Returns the three access bits for the block or False if the
+    inverted bits do not match the access bits.
+    '''
+    bits = BitArray([0])
+    inverted = BitArray([0])
+    # Block 0 access bits
+    if blocknum == 0:
+        bits = BitArray([accbits_str[11], accbits_str[23], accbits_str[19]])
+        inverted = BitArray([accbits_str[7], accbits_str[3], accbits_str[15]])
+
+    # Block 0 access bits
+    elif blocknum == 1:
+        bits = BitArray([accbits_str[10], accbits_str[22], accbits_str[18]])
+        inverted = BitArray([accbits_str[6], accbits_str[2], accbits_str[14]])
+    # Block 0 access bits
+    elif blocknum == 2:
+        bits = BitArray([accbits_str[9], accbits_str[21], accbits_str[17]])
+        inverted = BitArray([accbits_str[5], accbits_str[1], accbits_str[13]])
+    # Sector trailer / Block 3 access bits
+    elif blocknum == 3:
+        bits = BitArray([accbits_str[8], accbits_str[20], accbits_str[16]])
+        inverted = BitArray([accbits_str[4], accbits_str[0], accbits_str[12]])
+
+    # Check the decoded bits
+    inverted.invert()
+    if bits.bin == inverted.bin:
+        return bits
+    else:
+        return False
+
+
+
+
+def accbit_info(accbits):
+    '''
+    Returns  a dictionary of a access bits for all three blocks in a sector.
+    If the access bits for block could not be decoded properly, the value is set to False.
+    '''
+    decAccbits = {}
+    # Decode access bits for all 4 blocks of the sector
+    for i in range(0, 4):
+        decAccbits[i] = accbits_for_blocknum(accbits, i)
+    return decAccbits
+
+
+
+
+
 def print_info(data):
 
     blocksmatrix = []
+    blockrights = {}
 
     # determine what dump we get 1k or 4k
     if len(data) == 4096:
@@ -58,32 +110,44 @@ def print_info(data):
 
     # add colors for each keyA, access bits, KeyB
     for c in range(0, len(blocksmatrix)):
+        # Fill in the access bits
+        blockrights[c] = accbit_info(BitArray('0x'+blocksmatrix[c][3][12:20]))
+        # Prepare colored output of the sector trailor
         keyA =  bashcolors.RED + blocksmatrix[c][3][0:12] + bashcolors.ENDC
         accbits = bashcolors.GREEN + blocksmatrix[c][3][12:20] + bashcolors.ENDC
         keyB =  bashcolors.BLUE + blocksmatrix[c][3][20:32] + bashcolors.ENDC
         blocksmatrix[c][3] = keyA + accbits + keyB
 
+
     print("File size: %d bytes. Expected %d sectors" %(len(data),cardsize))
     print("\n\tUID:  " + blocksmatrix[0][0][0:8])
     print("\tBCC:  " + blocksmatrix[0][0][8:10])
     print("\tSAK:  " + blocksmatrix[0][0][10:12])
     print("\tATQA: " + blocksmatrix[0][0][12:14])
     print("                   %sKey A%s    %sAccess Bits%s    %sKey B%s" %(bashcolors.RED,bashcolors.ENDC,bashcolors.GREEN,bashcolors.ENDC,bashcolors.BLUE,bashcolors.ENDC))
-    print("╔═════════╦═════╦══════════════════════════════════╗")
-    print("║  Sector ║Block║            Data                  ║")
+    print("╔═════════╦═════╦══════════════════════════════════╦═══════════════╗")
+    print("║  Sector ║Block║            Data                  ║  Access Bits  ║")
     for q in range(0, len(blocksmatrix)):
-        print("╠═════════╬═════╬══════════════════════════════════╣")
+        print("╠═════════╬═════╬══════════════════════════════════╬═══════════════╣")
+
+        # z is the block in each sector
         for z in range(0, len(blocksmatrix[q])):
+            # Format the access bits. Print ERR in case of an error
+            accbits = ""
+            if isinstance(blockrights[q][z], BitArray):
+                accbits = bashcolors.GREEN + blockrights[q][z].bin + bashcolors.ENDC
+            else:
+                accbits = bashcolors.WARNING + "ERR" + bashcolors.ENDC
+
+            # Add Padding after the sector number
+            padLen = max(1, 5 - len(str(q)))
+            padding = " " * padLen
+            # Only print the sector number in the second third row
             if (z == 2):
-                if (len(str(q)) == 1):
-                    print("║    %d    ║  %d  ║ %s ║"  %(q,z,blocksmatrix[q][z]))
-                if (len(str(q)) == 2):
-                    print("║    %d   ║  %d  ║ %s ║"  %(q,z,blocksmatrix[q][z]))
-                if (len(str(q)) == 3):
-                    print("║    %d ║  %d  ║ %s ║"  %(q,z,blocksmatrix[q][z]))
+                print("║    %d%s║  %d  ║ %s ║      %s      ║"  %(q,padding,z,blocksmatrix[q][z], accbits))
             else:
-                print("║         ║  %d  ║ %s ║"  %(z,blocksmatrix[q][z]))
-    print("╚═════════╩═════╩══════════════════════════════════╝")
+                print("║         ║  %d  ║ %s ║      %s      ║"  %(z,blocksmatrix[q][z], accbits))
+    print("╚═════════╩═════╩══════════════════════════════════╩═══════════════╝")
 
 
 def main(filename):