#!/usr/bin/env python3
# run this before the script : `tshark -r access_cards.pcap -Y 'usb.src == "2.2.1"' -T fields -e usbhid.data > access_cards.data`

# This is the name of the file that contains the HID data. A line should look like `030000000000000000`
file_name = "access_cards.data"

# This should cover the most common key codes
keys =       "\x00\x00\x00\x00abcdefghijklmnopqrstuvwxyz1234567890\n\x00\x00\t -=[]\\#;'`,./"
keys_shift = "\x00\x00\x00\x00ABCDEFGHIJKLMNOPQRSTUVWXYZ!@#$%^&*()\n\x00\x00\t _+{}|~:\"~<>?"

# This will contain the converted characters
out = list()

# Do a barrel roll
with open(file_name) as f:
    line = bytes.fromhex(f.readline())
    while line:
        # Check if left shift or right shift is pressed
        if line[1] & 0x02 or line[1] & 0x20:
            c = keys_shift[line[3]]
        else:
            c = keys[line[3]]
        # Append to out if not a null byte
        if c != '\x00':
            out += c
        line = bytes.fromhex(f.readline())

# Spit it out
print("".join(out))