a easy way to gen pre-split key

get-chunk.py

import math

def _get_chunks(chunk_size=4, chars=None):
    if not chars:
        # chars = list('0123456789') # list('-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz')
        chars = list('-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz')

    m = chars_size = len(chars)
    output_size = 1
    while m < chunk_size:
        m = m * chars_size
        output_size = output_size + 1

    interval = float(m) / float(chunk_size)
    n = 1
    while n < m:
        ret = ''
        i = int(round(n))
        while i > 0:
            j = i % chars_size
            i = i / chars_size
            ret = chars[j] + ret
        ret = (chars[0] * (output_size - len(ret))) + ret
        yield ret
        n += interval

print(list(_get_chunks(64 * 64)))