trash hash seems to work

This commit is contained in:
Christoph J. Scherr 2023-04-21 22:54:21 +02:00
parent 7d34d3fa35
commit e0cf1b11f6
Signed by: PlexSheep
GPG Key ID: 25B4ACF7D88186CC
2 changed files with 88 additions and 0 deletions

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src/calchash.py Normal file
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# this is literal garbage
# does not even work for the bad hash
def calcHash():
message = list('A' * 4)
accu = int("a5a5a5a55a5a5a5a55555555aaaaaaaa", 16)
for i in range(0, len(message)):
message[i] = hex(ord(message[i]))[2:]
if len(message) % 16 != 0:
remainder = -((len(message) % 16) - 16);
for i in range(0, remainder):
message.append("FF")
chunks = []
for i in range(0, len(message), 16):
chunk = "".join(message[i:i+16])
chunks.append(chunk)
for B in chunks:
accu = accu ^ int(B, 16)
print(accu)
return accu
calcHash()

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src/trash-hash.py Normal file
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#!/usr/bin/env python3
"""
Dirty hash we were covered in an excercise for Week 16 of 2023 in cryptography
"""
import math
import random
DEFINED_INITIAL = bytearray(b'\xa5\xa5\xa5\xa5\x5a\x5a\x5a\x55\x55\x55\xaa\xaa\xaa')
def trash_hash(input: bytearray) -> bytearray:
print("original len is %s" % len(input))
# extend with 0xff if length is not multiple of 16
while len(input) % 16 != 0:
input.append(0xff)
# set n
n: int = math.ceil(len(input)/16)
print("len is %s" % len(input))
print("n is %s" % n)
# cut input into blocks with size 16
blocks = [bytearray(16)] * n # initializes with 0x00s
# print the empty blocks
#for block in blocks:
# print("block: %s" % block.hex())
#print('='*80)
for i in range(0, n):
blocks[i] = input[i*16:i*16 + 16]
# print the filled blocks
#for block in blocks:
# print("block: %s" % block.hex())
# initilaize accumulator A_0 with the following constant values:
A_list = [DEFINED_INITIAL] * n
# iterate over blocks
for index, block in enumerate(blocks):
if index == 0:
pass
thing = bytes(by0 ^ by1 for by0, by1 in zip(A_list[index - 1], block))
A_list[index] = bytearray(thing)
print("final thing: %s" % A_list[index])
A = bytearray(1)
A.pop()
return A.join(A_list)
def main():
some_bytes = bytearray(b'AAAA');
print("hashed: %s" % some_bytes.hex())
print('='*80)
hashed = trash_hash(some_bytes)
print('='*80)
print("hashed: %s" % hashed.hex())
if __name__ == "__main__":
main()