Converting from hex to binary without losing leading 0's python

I don't think there is a way to keep those leading zeros by default.

Each hex digit translates to 4 binary digits, so the length of the new string should be exactly 4 times the size of the original.

h_size = len(h) * 4

Then, you can use .zfill to fill in zeros to the size you want:

h = ( bin(int(h, 16))[2:] ).zfill(h_size)

This is actually quite easy in Python, since it doesn't have any limit on the size of integers. Simply prepend a '1' to the hex string, and strip the corresponding '1' from the output.

>>> h = '00112233aabbccddee'
>>> bin(int(h, 16))[2:]  # old way
'1000100100010001100111010101010111011110011001101110111101110'
>>> bin(int('1'+h, 16))[3:]  # new way
'000000000001000100100010001100111010101010111011110011001101110111101110'

Basically the same but padding to 4 bindigits each hexdigit

''.join(bin(int(c, 16))[2:].zfill(4) for c in h)