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This is how they do it!

[ezgif-2-a4c55b6128]

Well it's been a long time since I've posted something new... But today
I've got something big:

[ezgif-2-a4c55b6128]NFC Stickers act like new filters!!

Sometime last year I received an email from Doegox. A Belgium Hacker
(I know him for his work on the ICE-man repo of the proxmark readers/
writers).

We exchanged some information and this is what I received from him:

import sys
import hashlib

# Usage: pwd.py 04A03CAA1E7080
def getpwd(uid):
    uid = bytearray.fromhex(uid)
    h = bytearray.fromhex(hashlib.sha1(uid).hexdigest())
    pwd = ""
    pwd += "%02X" % h[h[0] % 20]
    pwd += "%02X" % h[(h[0]+5) % 20]
    pwd += "%02X" % h[(h[0]+13) % 20]
    pwd += "%02X" % h[(h[0]+17) % 20]
    return pwd

assert getpwd("04A03CAA1E7080") == "CD91AFCC"
assert getpwd("04112233445566") == "EC9805C8"
print("PWD:", getpwd(sys.argv[1]))


To most of you this might look like some random code.. But this is
actually very special... Xiaomi relies on a password for communication
between filter and air purifier. More information can be found on the
reverse engineering Github: Click

The type of NFC tags that are used are the NTAG213 tags (by NXP) How
they created the password was a secret until now!

They use the UUID (duhh its, unique for each filter) If we use the
above code and and insert a filter with UUID : 04A03CAA1E7080 we get
the password CD91AFCC.

As seen as in my Github filter snoop: Click

That means we can make our own filters now!

[giphy]Party hard.

This will significantly decrease the waste footprint from a whole
filter.. to just a sticker 

if you want to support me, buy a NFC sticker pack (yes they act as an
new filter in a Xiaomi Air Purifier)

I sell on Tindie

Special thanks to Doegox and an incredible programmer friend.

[giphy2]Programming.....

Published May 27, 2022By admin
Categorized as Hacking, Xaomi Air Purifier

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