proxmark3/client/scripts/mifare_access.lua

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local getopt = require('getopt')
copyright = ''
author = "Neuromancer"
version = 'v1.0.0'
desc = [[
This script tries to decode Mifare Classic Access bytes
]]
example = 'script run mifare_access -a 7F0F0869'
usage = [[
script run mifare_access -h -a <access bytes>
Arguments:
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-h : this help
-a <access bytes> : 4 bytes ACCESS CONDITIONS
]]
local DEBUG = true
local bxor = bit32.bxor
local band = bit32.band
local rshift = bit32.rshift
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---
-- A debug printout-function
local function dbg(args)
if not DEBUG then return end
if type(args) == "table" then
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local i = 1
while args[i] do
dbg(args[i])
i = i+1
end
else
print("###", args)
end
end
---
-- This is only meant to be used when errors occur
local function oops(err)
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print("ERROR: ",err)
return nil, err
end
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---
-- Usage help
local function help()
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print(copyright)
print(author)
print(version)
print(desc)
print('Example usage')
print(example)
end
local access_condition_sector_trailer = {}
access_condition_sector_trailer[0x0] = {'never','key A','key A','never','key A','key A'}
access_condition_sector_trailer[0x2] = {'never','never','key A','never','key A','never'}
access_condition_sector_trailer[0x4] = {'never','key B','key A|B','never','never','key B'}
access_condition_sector_trailer[0x6] = {'never','never','key A|B','never','never','never'}
access_condition_sector_trailer[0x1] = {'never','key A','key A','key A','key A','key A'}
access_condition_sector_trailer[0x3] = {'never','key B','key A|B','key B','never','key B'}
access_condition_sector_trailer[0x5] = {'never','never','key A|B','key B','never','never'}
access_condition_sector_trailer[0x7] = {'never','never','key A|B','never','never','never'}
local access_condition_data_block = {}
access_condition_data_block[0x0] = {'key A|B','key A|B','key A|B','key A|B'}
access_condition_data_block[0x2] = {'key A|B','never','never','never'}
access_condition_data_block[0x4] = {'key A|B','key B','never','never'}
access_condition_data_block[0x6] = {'key A|B','key B','key B','key A|B'}
access_condition_data_block[0x1] = {'key A|B','never','never','key A|B'}
access_condition_data_block[0x3] = {'key B','key B','never','never'}
access_condition_data_block[0x5] = {'key B','never','never','never'}
access_condition_data_block[0x7] = {'never','never','never','never'}
local function main(args)
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print( string.rep('--',20) )
print( string.rep('--',20) )
print()
local access = ''
-- Read the parameters
for o, a in getopt.getopt(args, 'ha:') do
if o == "h" then return help() end
if o == "a" then access = a end
end
if access == nil then return oops('empty ACCESS CONDITIONS') end
if #access == 0 then return oops('empty ACCESS CONDITIONS') end
if #access ~= 8 then return oops("Wrong length. Should be 4 hex bytes ACCESS CONDITIONS (e.g. 7F0F0869)") end
local c2_b = tonumber(string.sub(access, 1, 1), 16)
local c1_b = tonumber(string.sub(access, 2, 2), 16)
local c1 = tonumber(string.sub(access, 3, 3), 16)
local c3_b = tonumber(string.sub(access, 4, 4), 16)
local c3 = tonumber(string.sub(access, 5, 5), 16)
local c2 = tonumber(string.sub(access, 6, 6), 16)
local gpb = string.sub(access, 7, 8)
if bxor(c1, c1_b) ~= 0xF then print("!!! bitflip in c1") end
if bxor(c2, c2_b) ~= 0xF then print("!!! bitflip in c2") end
if bxor(c3, c3_b) ~= 0xF then print("!!! bitflip in c3") end
local ab = c1 * 256 + c2 * 16 + c3
for block = 0,3 do
print("--> block "..block)
-- mask bits for block
local abi = band(rshift(ab, block), 0x111)
-- compress bits
abi = band(abi + rshift(abi, 3) + rshift(abi, 6),7)
-- print(abi)
if block == 3 then
print(" KEYSECXA read: "..access_condition_sector_trailer[abi][1])
print(" KEYSECXA write: "..access_condition_sector_trailer[abi][2])
print(" ACCESS COND. read: "..access_condition_sector_trailer[abi][3])
print("ACCESS COND. write: "..access_condition_sector_trailer[abi][4])
print(" KEYSECXB read: "..access_condition_sector_trailer[abi][5])
print(" KEYSECXB write: "..access_condition_sector_trailer[abi][6])
else
print(" read: "..access_condition_data_block[abi][1])
print(" write: "..access_condition_data_block[abi][2])
print(" inc: "..access_condition_data_block[abi][3])
print("decr, transfer, restore: "..access_condition_data_block[abi][4])
end
end
print("GPB: "..gpb)
end
main(args)