class KnotHash(object):
def __init__(self):
self.circular_list = CircularList([i for i in range(256)])
self.pos = 0
self.skip = 0
def create_hash(self, s):
'''Creates a knot hash from a string of input'''
# create lengths from ASCII conversions
knot_lengths = [ord(c) for c in s]
# append standard end lengths
knot_lengths += [17, 31, 73, 47, 23]
# perform ties of each lenght 64 times
for i in range(64):
for l in knot_lengths:
self.tie(l)
# reduce hash to dense hash
dense_hash = self.__reduce()
# create and return final string of hex values
final_string = []
for n in dense_hash:
h = hex(n)
final_string.append(h.replace('0x', '').zfill(2))
return ''.join(final_string)
def reset(self):
'''Resets position and skip to 0'''
self.circular_list = CircularList([i for i in range(256)])
self.pos = 0
self.skip = 0
def tie(self, length):
'''Reverse portion of array for user-passed length, increases positiona
and skip tracker variables'''
# identify end of list
end = self.pos + length
# creat sub-array and reverse
sub = self.circular_list.index(self.pos, end)
reverse = sub[::-1]
# replace all values
self.circular_list.replace(self.pos, reverse)
# move position
self.pos = end + self.skip
if self.pos > len(self.circular_list.array):
self.pos %= len(self.circular_list.array)
# increase skip size
self.skip += 1
def __reduce(self):
'''Reduces a hash to a dense hash'''
# create empty list to populate with dense hash
dense_hash = []
# iterate through array in groups of 16
pos = 0
while pos < len(self.circular_list.array):
num = xor(self.circular_list.index(pos, pos + 16))
dense_hash.append(num)
pos += 16
return dense_hash
