check_qr.py

vote_id_1 = 14399212
expected_qr_1 = 'EH1RQ'

vote_id_2 = 20516201
expected_qr_2 = 'W2231'


def get_card_number(gr_string):
    # Constants
    MODULUS = 60466176
    OFFSET = 46913010
    # The CORRECT Modular Multiplicative
    INVERSE = 46213067
    x = int(gr_string, 36)
    card_number = (INVERSE * (x - OFFSET)) \
                  % MODULUS
    return card_number


def excel_base_mod(vote_id):
    r = (35477987 * vote_id + 46913010) % 60466176
    if r == 0:
        return '0'
    digits = []
    while r > 0:
        remainder = r % 36
        if remainder < 10:
            digits.append(str(remainder))
        else:
            digits.append(chr(ord('a') + remainder - 10))
        r //= 36
    return ''.join(reversed(digits))


result1 = excel_base_mod(vote_id_1)
result2 = excel_base_mod(vote_id_2)

print(f'Vote ID {vote_id_1}: calculated={result1.upper()}, expected={expected_qr_1}, match={result1.upper() == expected_qr_1}')
print(f'Vote ID {vote_id_2}: calculated={result2.upper()}, expected={expected_qr_2}, match={result2.upper() == expected_qr_2}')
print('-' * 80)

expected_qr_3 = 'NZSCW'
a = get_card_number(expected_qr_3)
b = excel_base_mod(a)
print(f'✅Found QR code for Vote ID {a}->{b.upper()}')

for i in range(0, 100_000_000):
    result = excel_base_mod(i).upper()
    if result.upper() == expected_qr_3:
        print(f'✅Found QR code for Vote ID {i}->{expected_qr_3}')
        break
else:
    print(f'❌Not found QR code for {expected_qr_3}!')

print('-' * 80)