[PYTHON-CRYPTO] string <-> int conversion

[Bram Cohen]

On Fri, 9 Nov 2001, Paul Rubin wrote:

> The python library has no direct base 256 conversion function and it's
> too late to get a patch into 2.2.  However, converting long to hex
> with hex(...) and then using binascii for binary output, or binascii
> for binary to hex followed by long(h,16) to convert hex to long, is
> reasonably fast.

Thanks, I feel stupid now. I cleaned up my routines to work that way, here
are the nicer versions -

from binascii import b2a_hex, a2b_hex

def int_to_binary(numin, size):
    x = hex(numin)[2:]
    if x[-1] == 'L':
        x = x[:-1]
    if len(x) % 2 == 1:
        x = '0' + x
    x = a2b_hex(x)
    x = ('\000' * (size - len(x))) + x
    return x

def binary_to_int(s):
    return long(b2a_hex(s), 16)

I hate hate hate the int/long distinction and will do a dance on long()'s
grave when it's gone.

-Bram Cohen

"Markets can remain irrational longer than you can remain solvent"
                                        -- John Maynard Keynes